Security-Widefield, CO PFAS Exposure Assessment Report

Security-

Wideﬁeld

El Paso County | Colorado

INFORMATION TO PROTECT OUR COMMUNITIES

Per- and Polyﬂuoroalkyl

Substances (PFAS)

Exposure Assessment

REPORT

6/14/22

Table of Contents

Abbreviations .................................................................................................... iii

Executive Summary ....................................................................................... ES-1

Background and Purpose ........................................................................................................... ES-1

Exposure Assessment Activities ................................................................................................. ES-2

Security-Widefield Community-Wide Findings ............................................................................ ES-3

Limitations ................................................................................................................................ ES-6

Recommendations .................................................................................................................... ES-6

For More Information ................................................................................................................ ES-8

Background and Purpose .................................................................................... 1

What Are PFAS? ............................................................................................................................. 1

Why Security-Widefield? ................................................................................................................ 3

Methods ............................................................................................................. 4

Sampling Frame .............................................................................................................................. 4

Participant Eligibility ....................................................................................................................... 6

Participant Recruitment.................................................................................................................. 6

Data Collection and Analysis ........................................................................................................... 6

Results .............................................................................................................. 13

Profile of Security-Widefield (El Paso County) EA Participants ........................................................ 13

Comparison of Security-Widefield EA Participants’ Demographics to Sampling Frame

Demographics .............................................................................................................................. 15

PFAS in Blood ............................................................................................................................... 16

PFAS in Urine ............................................................................................................................... 34

PFAS in Tap Water ........................................................................................................................ 35

PFAS in Household Dust ................................................................................................................ 36

Discussion ......................................................................................................... 38

Generalizability of Security-Widefield EA Community Statistics ..................................................... 39

Relationships Between Demographics and PFAS Blood Levels ........................................................ 39

Significance of Drinking Water Exposures ...................................................................................... 40

Other Exposure Characteristics ..................................................................................................... 42

Security-Widefield Community-Wide Findings .................................................. 42

Limitations ................................................................................................................................... 45

Recommendations ....................................................................................................................... 46

For More Information ................................................................................................................... 47

References ........................................................................................................ 48

Appendix A: Additional Tables

Appendix B: Additional Background Statistics

Appendix C: PFAS Blood Levels by Demographics and Exposure Characteristics

Tables

Table 1. Summary of recruitment and data collection efforts ..................................................................... 9

Table 2. List of PFAS measured for in blood, urine, tap water, and dust ................................................... 10

Table 3. Characteristics of Security-Widefield EA participants ................................................................... 14

Table 4. Demographic comparison of EA participants and the sampling frame population ...................... 16

Table 5. Community statistics for PFAS in blood in micrograms per liter .................................................. 17

Table 6. Geometric means for PFAS in blood in micrograms per liter, unadjusted and age-adjusted to

the sampling frame ..................................................................................................................................... 18

Table 7. Comparison of PFAS blood geometric means (GMs) and 95th percentiles in Security-

Widefield, Colorado, with the U.S. population (NHANES 2015–2016) in micrograms per liter ................. 20

Table 8. Pearson correlation coefficients between PFAS in blood (log) ..................................................... 21

Table 9. Summary of statistically significant variables (p<0.05) in multivariate regression models .......... 23

Table 10. Community statistics for PFAS in urine reported in micrograms per liter .................................. 35

Table 11. Summary statistics for dust samples (n=18) collected in Security-Widefield ............................. 36

Figures

Figure 1. Sampling frame for the Security-Widefield Exposure Assessment ................................................ 5

Figure 2. Distribution of PFAS blood levels (log scale) ................................................................................ 18

Figure 3. EA average PFAS blood levels compared to national levels ........................................................ 21

Figure 4. PFAS blood levels in adults and children (log scale) .................................................................... 25

Figure 5. PFAS blood level in adults by sex (log scale) ................................................................................ 26

Figure 6. PFAS blood level in adults by drinking water source (log scale) .................................................. 27

Figure 7. PFAS blood level in adults by filter type (log scale) ..................................................................... 28

Figure 8. PFAS blood level in adults by tap water consumption rates (log scale) ...................................... 29

Figure 9. PFAS blood levels in adults by length of residence in sampling frame (log scale) ....................... 30

Figure 10. PFAS blood level in adults by public water supply (log scale) .................................................... 31

Figure 11. PFAS blood level in adults by occupational history (log scale) .................................................. 32

About ATSDR

The Agency for Toxic Substances and Disease Registry (ATSDR) is a federal

public health agency of the U.S. Department of Health and Human Services

(HHS). ATSDR works with other agencies and state, tribal and local

governments to protect communities from harmful health effects related

to exposure to natural and manmade hazardous substances. For more

information about ATSDR, visit https://www.atsdr.cdc.gov/

iii

Abbreviations

9Cl-PF3ONS 9-chlorohexadecafluoro-3-oxanone-1-sulfonic acid

11Cl-PF3OUdS 11-chloroeicosafluoro-3-oxaundecane-1-sulfonic acid

AFCEC Air Force Civil Engineer Center

AFFF aqueous film forming foam, also known as “A triple F”

ATSDR Agency for Toxic Substances and Disease Registry

CDC Centers for Disease Control and Prevention

DONA 4,8-dioxa-3H-perfluorononanoic acid

EA exposure assessment

EPA U.S. Environmental Protection Agency

EtFOSAA N-ethyl perfluorooctanesulfonamidoacetic acid

FOD frequency of detection

FtS 4:2 fluorotelomer sulfonic acid 4:2

FtS 6:2 fluorotelomer sulfonic acid 6:2

FtS 8:2 fluorotelomer sulfonic acid 8:2

GAC granular activated carbon

HA health advisory

HFPO-DA (GenX) hexafluoropropylene oxide dimer acid

LOD limit of detection

MeFOSAA N-methyl perfluorooctanesulfonamidoacetic acid

MHP mobile home park

µg/L, or ug/L micrograms per liter (same as parts per billion or 1,000 parts per trillion)

ng/g nanograms per gram (same as parts per billion or micrograms per kilogram)

NHANES National Health and Nutrition Examination Survey

N-EtFOSA N-ethyl perfluorooctanesulfonamide

N-EtFOSE N-ethyl perfluorooctanesulfonamidoethanol

N-MeFOSA N-methyl perfluorooctanesulfonamide

N-MeFOSE N-methyl perfluorooctanesulfonamidoethanol

n-PFOA linear isomer of PFOA

n-PFOS linear isomer of PFOS

PFAS per- and polyfluoroalkyl substances

PFAS-AWARE PFAS Assessment of Water and Resident Exposure

PFBA perfluorobutanoic acid

PFBS perfluorobutane sulfonic acid

PFDA perfluorodecanoic acid

PFDoA perfluorododecanoic acid

PFDS perfluorodecane sulfonic acid

PFDoS perfluorododecanesulfonate

PFHpA perfluoroheptanoic acid

PFHpS perfluoroheptane sulfonic acid

PFHxA perfluorohexanoic acid

PFHxS perfluorohexane sulfonic acid

PFNA perfluorononanoic acid

PFNS perfluorononane sulfonic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctane sulfonic acid

PFOSA perfluorooctanesulfonamide

PFPeA perfluoropentanoic acid

PFPeS perfluoropentane sulfonic acid

PFTA perfluorotetradecanoic acid

PFTrA perfluorotridecanoic acid

PFUnA perfluoroundecanoic acid

ppt parts per trillion (same as 1 nanogram per liter)

Sb-PFOA branched isomers of PFOA

Sm-PFOS branched isomers of PFOS

WD water district

WSD water and sanitation district

ES-1

Executive Summary

Background and Purpose

PFAS (or per- and polyfluoroalkyl substances) are a family of synthetic chemicals that have been used in

industry and consumer products since the 1950s. There are thousands of different PFAS. This

assessment discusses some of the most commonly studied PFAS, including perfluorooctanoic acid

(PFOA), perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonic acid (PFHxS), perfluorononanoic

acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnA), and N-methyl

perfluorooctanesulfonamidoacetic acid (MeFOSAA).

PFAS do not occur naturally but are widespread in the environment. They have been found in soil,

water, air, and animal and plant life. Most PFAS (including PFOA, PFOS, PFHxS, and PFNA) are either very

resistant to breaking down or degrade into other PFAS that do not degrade further. Major exposure

routes for PFAS include drinking contaminated water and eating contaminated food, but exposure can

also occur through other routes (i.e., ingestion of contaminated dust). Once PFAS enter people’s bodies,

some of them (including PFOA, PFOS, PFHxS, and PFNA) can remain in the body for long periods and can

be measured in the blood years after exposure. Most people in the United States have been exposed to

PFAS. At least one PFAS was detected in more than 99% of National Health and Nutrition Examination

Survey (NHANES) samples collected for the 1999-2000 survey cycle.

The Centers for Disease Control and Prevention (CDC) and the Agency for Toxic Substances and Disease

Registry (ATSDR) are conducting exposure assessments (EAs) in communities that were known to have

PFAS in their drinking water and are near current or former military bases. This report shares results

from the community of Security-Widefield in El Paso County, Colorado, near Peterson Air Force Base

(the Base). When all EAs are complete, ATSDR will prepare a report describing the results across all sites.

Possibly as early as the 1970s, the Base used aqueous film forming foam (AFFF) containing PFAS for its

firefighter training. Over time, the PFAS from the AFFF entered the ground, moved into the groundwater

to offsite locations, and affected nearby municipal wells. PFAS were first detected in municipal wells

downgradient of the Base in 2013. The affected wells supplied water to customers from the Security

Water District (WD), the western portion of the Widefield Water and Sanitation District (WSD), and the

Security Mobile Home Park (MHP). Between January and November of 2016, Security WD and Widefield

WSD inactivated their contaminated groundwater wells and shifted to uncontaminated surface water

sources. In 2017, Widefield WSD installed an ion exchange system to treat PFAS in water from its

contaminated wells. Security WSD currently uses uncontaminated surface water sources. Residents of

Security MHP were provided bottled water beginning in the summer of 2016 until a treatment system

was installed in November of 2017. From 2018 to 2019, a PFAS Assessment of Water and Resident

Exposure (PFAS AWARE) study was conducted by the Colorado School of Public Health and the Colorado

School of Mines that evaluated exposure to PFAS in drinking water in the El Paso County community.

The PFAS AWARE study evaluated 200 participants in 2018 and resampled 50 of the participants in 2019.

The study evaluated serum PFAS along with markers of health related to liver function, cholesterol, and

immune response. The results of the study indicated that the primary source of PFAS in people’s blood

was PFAS in the drinking water.

Based on the information ATSDR has reviewed, the public drinking water supplies in Security-Widefield

currently meet or are below the U.S. Environmental Protection Agency’s (EPA) 2016 health advisory

(HA). At this time, ATSDR does not recommend community members who get drinking water from

Security WD, Widefield WSD, or Security MHP use alternative sources of water.

ES-2

This EA assessed PFAS levels in the blood and urine of Security-Widefield residents. Test results were

compared to PFAS levels in a nationally representative sample. Tap water and indoor dust samples from

a subset of households were analyzed. These EA results will help participants and their communities

better understand their PFAS exposure, allow ATSDR to provide recommendations to reduce exposure,

and inform public health efforts related to protecting communities from sources of PFAS other than

contaminated drinking water supplies.

ATSDR will use the data collected from this and other EAs to help inform future studies of PFAS

exposure.

Exposure Assessment Activities

ATSDR invited a randomly selected sample of Security-Widefield households to participate in this EA. To

be eligible to participate, household residents must have (1) been served by the drinking water systems

of Security Water District (WD), Security Mobile Home Park (MHP), or the western portion of the

Widefield Water and Sanitation District (WSD) for at least 1 year before November 10, 2016 (these

residents have the greatest likelihood of past exposures to PFAS via drinking water), (2) been greater

than three years old at the time of sample collection, and (3) not been anemic or had a bleeding

disorder that would prevent giving a blood sample. Results from randomly selected households allow

ATSDR to estimate exposure for all community members, even those who were not tested.

In September 2020, 346 eligible people (318 adults and 28 children) from 188 households participated in

the EA sample collection event. ATSDR performed the following tasks:

• administered exposure history questionnaires to all participants

• collected blood and urine samples from every participant

• collected tap water and dust samples from the homes of 18 randomly selected participants

• tested for 7 PFAS in blood, 14 in urine, 18 in water, and 33 in dust

• measured PFHxS, PFOS, PFOA, PFNA, PFDA, and PFUnA across all media (blood, urine, tap water,

and dust)

• mailed individual biological and environmental results to participants in May 2021

This report summarizes community PFAS blood levels, measured in serum, for the group of Security-

Widefield residents who participated in the EA. In this report, when we write blood levels of PFAS, we

are referring to the measurement of PFAS in the serum fraction of the blood. This report also

summarizes urine sample results from a subset of participants and presents results from the dust and

tap water samples. Finally, the relationships between blood results and the environmental sampling

data are explored. The Security-Widefield blood and urine results are compared to a nationally

representative sample of the US population. Specifically, ATSDR compared Security-Widefield data to

those collected by CDC as part of its National Health and Nutrition Examination Survey (NHANES). The

NHANES survey collects blood and urine samples from a representative sample of the civilian non-

institutionalized U.S. population and tests them for chemicals, including PFAS. PFAS levels are also

shown by age, race/ethnicity, sex, number of years living in the community, drinking water consumption

patterns, and other exposure parameters.

The laboratory reports branched and linear isomers of PFOA and PFOS in blood and urine. ATSDR reports on the

sum of the individual isomer concentrations of PFOA and PFOS.

ES-3

The samples were collected and analyzed in accordance with ATSDR’s Exposure Assessment Protocol:

Biological and Environmental Sampling of PFAS (EA protocol) to ensure their quality. This EA was

designed to estimate geometric mean concentrations of PFOS in blood for the sampling frame (i.e., the

Security-Widefield area served by the drinking water systems of the Security WD, Security MHP, and the

western portion of the Widefield WSD) population, with a precision goal of 15% or less. The precision is

a measure of how wide the confidence interval is around the estimated geometric mean. ATSDR met

this goal for PFOS, and precision for all PFAS measured in this EA ranged from approximately 3.9% to

16%. ATSDR also calculated geometric means that were adjusted to the age distribution of the sampling

frame population to correct for participation bias and to provide an estimate that is more generalizable

to the sampling frame community. ATSDR also calculated geometric means that were adjusted to the

national age distribution for comparison with the 2015–2016 NHANES survey. To assess possible

relationships between blood levels and various demographic and exposure variables, ATSDR used

statistical models. Univariate statistics, which evaluate one variable at a time, were used as a tool to

examine the data broadly and find patterns within the data. Multivariate statistics and regression

modeling were used to simultaneously account for multiple variables and to control for potential

confounding factors.

In this report we use the term ‘average’ to refer to the national age-adjusted

geometric mean.

Security-Widefield Community-Wide Findings

Finding 1. Average blood levels of PFHxS and PFOA in the Security-Widefield EA site

participants are higher than national levels. Averages of other PFAS were not higher than the

national levels or were detected too infrequently to compare to national levels.

Geometric means (i.e., averages) for PFHxS and PFOA blood levels were statistically higher (p<0.05) in

Security-Widefield EA participants when compared to CDC’s NHANES (2015–2016) testing, which was

limited to people over 12 years old. The statistically higher blood PFAS levels were observed for both

unadjusted geometric means for all EA participants and geometric means adjusted to the age

distribution of the U.S. population from NHANES 2015–2016.

Of the PFAS analyzed in blood, PFHxS had the largest elevations when compared to national levels. The

age-adjusted geometric mean blood PFHxS level among EA participants was 6.8 times the national level.

Blood PFHxS levels were above the national geometric mean for 96% of the Security-Widefield EA

participants and above the NHANES 95

percentile for 75% of the participants. The age-adjusted

geometric mean blood PFOA level was 1.2 times the national level.

Other PFAS measured in this EA (PFOS, PFNA, PFDA) were not higher than national levels. ATSDR was

unable to compare the geometric mean MeFOSAA levels because MeFOSAA was detected in less than

60% of NHANES samples. PFUnA was detected in less than 60% of the EA participant samples; due to the

large percentage of samples below the limit of detection, geometric means were not calculated.

Finding 2. Elevated blood levels of PFHxS and PFOA may be associated with past drinking

water contamination.

PFHxS, PFOS, and PFOA were detected in Security-Widefield water systems as early as 2013, though

contamination likely began earlier. Two of these PFAS (PFHxS and PFOA) had statistically elevated blood

A confounding variable is a factor that may distort or mask the relationship between a potential predictor and

measure of exposure.

ES-4

levels compared to national geometric means. The maximum concentrations observed in drinking water

in Security-Widefield water systems were 590 ppt for PFHxS, 210 ppt for PFOS, and 90 ppt for PFOA.

By November 2016, actions taken by the three affected water systems reduced PFAS levels in drinking

water below EPA’s HA for PFOS and PFOA. Before 2016, PFAS-containing AFFF were primarily

formulated with PFOS, but also contained various PFAS precursors that could break down in the

environment into other PFAS, such as PFHxS, which could explain the elevated blood PFHxS levels.

PFHxS and PFOA have very long biological half-lives (on the order of years). There were 3 years and 10

months between when the water systems took action to reduce exposure to contaminated drinking

water and collection of biological samples during the EA. Because of the long half-lives of PFHxS and

PFOA, past drinking water exposures may have contributed to the EA participants’ blood levels. PFHxS

has the longest estimated half-life of the three compounds (up to 35 years), which may contribute to

why it exceeded the NHANES 2015-2016 geometric mean by the largest margin.

PFHxS and PFOA were highly correlated in Security-Widefield EA participants’ blood (Pearson correlation

coefficient, r = 0.73). This means that, typically, residents who had elevated blood PFHxS levels also had

elevated blood PFOA levels. This correlation suggests a common exposure source, such as the pre-2017

Security-Widefield public drinking water supplies, though other sources of exposure may also have

contributed to the observed blood levels.

Additional observations from the multivariate analyses support the finding that past exposure to

contaminated drinking water may have contributed to the elevated blood levels.

• First, a consistent and statistically significant predictor of participant blood levels for PFHxS and

PFOA was how long the resident had lived in Security-Widefield during the past 20 years. Each

year of residence in the sampling frame over the past 20 years was associated with a 7.1%

increase in PFHxS levels and a 2.0% increase in PFOA levels.

• Second, adults who reported not drinking tap water at all at home on average had statistically

lower PFHxS (36%) and PFOA (24%) blood levels when compared to those who reported drinking

tap water at home with no filter or treatment device.

Multivariate models conducted separately for males and females suggest differences in the associations

(between blood levels and residency duration/tap water consumption) between males and female

participants.

Taken together, the data suggest that past drinking water exposure contributed to the elevated blood

levels of PFHxS and PFOA observed in the Security-Widefield EA participants.

Finding 3. Age, sex, occupational exposure, kidney disease history, local fruit and vegetable

consumption, and home cleaning frequency were associated with some PFAS blood levels.

PFAS blood levels varied with different demographic and exposure characteristics of the participant

population. The following relationships were statistically significant in multivariate analyses in the

Security-Widefield EA dataset in adult participants:

• Blood levels of PFHxS, PFOS, and PFOA were higher in older participants, and the size of the

effect varied by sex for PFHxS. In males, blood levels for these compounds increased by 1.0% to

1.7% for every year of participant age. In females, blood levels for these compounds increased

by 1.0% to 2.5% for every year of participant age.

ES-5

• Males had statistically higher blood levels of PFHxS and PFOS than females. PFOS blood levels in

males were 42% higher than in females. For PFHxS, the difference between males and females

was larger in younger people. For example, 30-year-old males had higher blood PFHxS levels

than 30-year-old females by 70%. For 50-year-old males, this difference was reduced to 35%.

• Adult participants who reported at least one occupational exposure in the past 20 years on

average had lower PFHxS (28%) than adult participants who reported no occupational exposures

in the past 20 years. Although this result was the opposite of expected, it is based on a relatively

small sample of participants with occupational exposure and should be interpreted with caution.

• Adult participants who reported a history of kidney disease had PFHxS blood levels that were

39% lower than those who did not. This result is based on a relatively small sample of

participants self-reporting a history of kidney disease and should be interpreted with caution.

• Adult EA participants who reported any consumption of locally grown fruits or vegetables had

blood PFOS levels that were 52% higher compared to participants who reported no such

consumption. While PFOS levels were higher in participants who reported consuming local

produce compared to those who did not, PFOS blood levels were not elevated in the

community.

• Adult participants who reported cleaning their homes three times per week or more on average

had 24% higher PFOS blood levels than adult participants who reported cleaning their homes a

few times per month or less; however, PFOS blood levels were not elevated in the community.

A few associations were observed in children (<18 years) in univariate analyses, though many variables

could not be examined because of the small number of child participants (n=28). Because of the small

sample size, results should be interpreted with caution. Specifically, the longer a child was breastfed, the

higher blood levels of PFOS and PFOA compared to non-breastfed children, and children that reported

ever drinking formula reconstituted with tap water on average had blood PFHxS, PFOS, and PFOA levels

that were lower than children that reported never drinking formula reconstituted with tap water.

Infants born to mothers exposed to PFAS can be exposed in utero and while breastfeeding. However,

based on current science, the benefits of breastfeeding outweigh the risks for infants exposed to PFAS in

breast milk. The final report on all EA sites will include a more robust analysis of children.

Finding 4. Only one PFAS was detected in urine and at relatively low concentrations.

ATSDR analyzed 36 (10%) of the urine samples collected. Only perfluorobutanoic acid

(PFBA) was detected; it was detected in 2.8% of the 36 samples that were analyzed. ATSDR did not

analyze all participants’ urine samples because none of the species were detected in more than 60% of

the samples analyzed.

Finding 5. All Security-Widefield drinking water samples collected during the EA in 2020 met

the EPA’s HA for specific PFAS in drinking water.

This is based on 17 filtered and 17 unfiltered water samples collected in 18 households during the EA.

These results are consistent with recent data collected from the Widefield WSD, Security WD, and

Security MHP water systems.

Finding 6. Patterns and levels of dust contamination measured in participating EA households

are comparable to those reported in selected U.S. studies.

Among the PFAS detected most frequently in household dust samples, N-MeFOSE and PFOS were

measured at the highest average concentrations. No nationally representative comparison values are

available, but geometric mean and median concentrations for PFAS measured in dust collected in the

ES-6

small subset of participating households (n=18) were within the range of levels reported in a few

published studies of other U.S. communities (with or without known PFAS contamination). Of the PFAS

measured in this EA’s household dust samples, PFOA (r=0.46) and MeFOSAA (r=0.57) were statistically

correlated with the same PFAS measured in participants’ blood. The final report on all EA sites will

include a more robust comparison of PFAS measured in dust and blood.

Limitations

There are several limitations associated with this assessment.

• The random sampling recruitment method used for this EA was designed to measure blood PFAS

concentrations that were generalizable to all Security-Widefield residents who were customers

of the Security WD, Widefield WSD, or Security MHP. However, the EA participant sample may

not be fully representative of the community. Only 6.3% of the households from the random

sample participated in the EA. Participant characteristics were different than those of the area’s

overall population. Participants were older, more likely to identify as White, and less likely to

identify as more than one race. ATSDR addressed some of these differences by calculating

geometric mean estimates that were adjusted to the age distribution of the community.

• Measurement of blood, urine, and environmental PFAS concentrations in EA participants may

improve the understanding of exposure in this community but will not provide information

about all sources of exposure. Additionally, identifying every potential confounding exposure is

not possible.

• There are challenges in measurement of trace levels of PFBA in urine, including selectivity of the

analytical instrumentation and potential for external contamination. Therefore, we advise

caution when interpreting the PFBA results in urine.

• Multivariate regression models explained a small to moderate portion of the variability in

participants’ blood PFAS levels (R-squared or R

, a measure of model goodness-of-fit, ranged

between 0.13 and 0.30 in all-adult models). This means that other factors not identified could

influence the relationships reported in this assessment (see “Statistical Analysis” section for

details).

• This EA did not directly assess participants’ tap water consumption prior to the reduction of

PFAS in the municipal water systems.

• This EA was not designed to investigate health problems associated with exposure to PFAS.

Without additional information about exposure-response relationships, the results of this EA

cannot be used to assess current or past health problems or predict the future occurrence of

disease. PFAS found in a person’s blood or urine means that exposure has occurred. The

presence of PFAS in blood or urine does not tell us how, where, when, or for how long a person

was exposed to PFAS. Exposure to PFAS does not mean adverse health effects will result, either

now or in the future.

• The dust results are exploratory and should be interpreted with caution. They are based on a

limited set of samples, and in some cases those samples are based on a small sample mass.

Recommendations

This PFAS EA provides evidence that past exposures to PFAS in drinking water have impacted the levels

of PFAS in people’s bodies. These PFAS are eliminated from the body over a long period of time. This

allowed ATSDR to measure PFAS even though exposures through drinking water were mitigated, or

lowered, years ago.

ES-7

Although the exposure contribution from PFAS in drinking water in Security-Widefield has been

mitigated, there are actions community members and county officials can take to further reduce

exposures to PFAS and protect public health.

Based on the PFAS drinking water test results from drinking water wells in Security-Widefield, ATSDR

does not recommend an alternate source of drinking water at this time.

1. What the Security WD, Widefield WSD, and Security MHP can/should do:

a. Operators of these three public water systems should continue to monitor concentrations of

PFAS in drinking water delivered to the Security-Widefield community to ensure that

concentrations of PFAS remain below the EPA’s HA or other applicable guidelines for specific

PFAS in drinking water. Results of PFAS monitoring should be shared with community

members through appropriate communication channels (Consumer Confidence Reports for

Security WD: http://securitywsd.com/water-quality/; Consumer Confidence Reports for the

Widefield WSD, https://www.wwsdonline.com/consumer-confidence-report).

b. All treatment systems to remove PFAS from the municipal drinking water in Security-

Widefield should be maintained appropriately to ensure that PFAS concentrations remain

below the EPA’s HA or other applicable guidelines for specific PFAS in drinking water.

2. What community members can/should do:

a. Become familiar with Consumer Confidence Reports for information on water quality in

Security-Widefield (Consumer Confidence Reports for Security WD:

http://securitywsd.com/water-quality/; Consumer Confidence Reports for the Widefield

WSD, https://www.wwsdonline.com/consumer-confidence-report).

b. Private well owners living in the area affected by PFAS should consider having their wells

tested for PFAS if testing has not been conducted before. To learn more about testing wells

for PFAS visit:

https://www.elpasocountyhealth.org/news/news-release/2019/resources-

for-pfc-water-contamination-and-testing. Global public health organization NSF

International has developed a test method to verify a water filter’s ability to reduce PFOA

and PFOS to below the health advisory levels set by the EPA. NSF International-approved

devices can be found at: https://info.nsf.org/Certified/DWTU/ Click on “reduction devices”

at the bottom of the page for PFOA and PFOS.

c. Nursing mothers should continue breastfeeding. Based on current science, the known

benefits of breastfeeding outweigh the risks for infants exposed to PFAS in breast milk.

d. When possible, eliminate or decrease potential exposure to PFAS in consumer products,

such as stain-resistant products and food packaging materials. To learn more visit:

https://www.fda.gov/food/chemical-contaminants-food/questions-and-answers-pfas-food

e. Pay attention to advisories about food consumption, such as local fish advisories.

f. Discuss any health concerns or symptoms with your health care provider. Share results of

PFAS blood testing with your health care provider and make them aware of ATSDR

resources for clinicians (https://www.atsdr.cdc.gov/pfas/resources/info-for-health-

professionals.html). Follow the advice of your health care provider and the

recommendations for checkups, vaccinations, prenatal care, and health screening tests.

g. At this time, ATSDR does not have plans to conduct additional blood testing for PFAS nor

recommend PFAS EA participants get individually retested for PFAS in blood. The biological

half-lives of many of the PFAS measured in people’s blood are long. PFHxS has one of the

longest half-lives. This means that PFAS blood levels are not expected to change significantly

ES-8

in the near-term, even if exposure stops. Additionally, it is unclear what an individual’s PFAS

test results mean in terms of possible health effects.

For the general population blood tests for PFAS are most useful when they are part of a

scientific investigation like this EA. Test results will tell you how much of each PFAS is in your

blood, but it is unclear what the results mean in terms of possible health effects. In addition,

blood testing for PFAS is not a routine test offered by most doctors or health departments. If

you are concerned about the effect of PFAS on your health, talk to your health care provider

and make them aware of ATSDR resources for clinicians

(https://www.atsdr.cdc.gov/pfas/resources/info-for-health-professionals.html

h. ATSDR is funding a multi-site health study, including one site in the El Paso County area

called the Colorado Study on Community Outcomes from PFAS Exposure (CO-SCOPE). The

CO-SCOPE is being conducted by the same investigative team that completed the PFAS

AWARE study. The study will evaluate PFAS levels in serum as well as health markers and

neurobehavioral outcomes in children. If you are interested in being included in the study or

want further information, please contact

Fountain Valley PFAS Study | PFAS Multi-Site Study

Colorado: CO SCOPE (co-scope.org)

i. Follow the advice of your child’s health care provider and the recommendations for well

child checkups, vaccinations, and recommended health screening tests. Consult

https://health.gov/myhealthfinder

to help identify those vaccinations and tests.

j. For additional information about environmental exposures and children’s health, contact

the Pediatric Environmental Health Specialty Units, a nationwide network of experts in

reproductive and children’s environmental health (https://www.pehsu.net/

For More Information

If you have questions or comments or want more information on the Security-Widefield EA site, call

800-CDC-INFO or email [email protected]v. For more information on the work CDC/ATSDR is doing to address

PFAS exposure, visit ATSDR’s PFAS website: https://www.atsdr.cdc.gov/pfas/. For other EA or PFAS-

related questions, email [email protected].

Background and Purpose

The Centers for Disease Control and Prevention (CDC)

and the Agency for Toxic Substances and Disease

Registry (ATSDR) are conducting exposure

assessments (EAs) in communities near current or

former military bases that are known to have had per-

and polyfluoroalkyl substances (PFAS) in their drinking

water. One of these communities is Security-Widefield

in El Paso County, Colorado. This report summarizes

the findings of the Security-Widefield EA. When all

EAs are complete, ATSDR will prepare a report

describing the results across all sites.

The EA involved collecting responses to exposure

history questionnaire responses, biological samples

(blood and urine), and environmental samples (tap

water and household dust). ATSDR collected biological samples at the Security Village Fire Station

between September 15 and September 28, 2020. During this same time frame, ATSDR administered

questionnaires over the phone and took water and dust samples in a subset of randomly chosen

participant homes.

The results of the EA:

The EA does not look at what types of health problems are associated with exposure and is not meant to

determine if PFAS levels in blood or urine are risk factors for illness now or later in life. Additionally, the

EA does not tell us exactly how or where people were exposed or when or how long PFAS exposure

lasted.

ATSDR’s Exposure Assessment Protocol: Biological and Environmental Sampling of PFAS, termed the

PFAS EA Protocol [ATSDR 2019a], provides additional background, describes the criteria for selecting

communities for the EAs, and highlights the procedures ATSDR used in conducting the EAs.

What Are PFAS?

Human exposure to PFAS is a growing environmental health concern. PFAS are synthetic chemicals used

in many industries and consumer products since the 1950s. They have been used in nonstick cookware;

water-repellent clothing; stain-resistant fabrics and carpets; cosmetics; firefighting foams; and products

• tell us the amount of PFAS in the blood of individual participants and the Security-Widefield

community and how these levels compare to the general U.S. population,

• tell us the amount of PFAS in the urine of individual participants and the EA community and how

these levels compare to the general U.S. population,

• provide a better understanding of environmental factors that affect PFAS exposure,

• provide information that may be used to stop or reduce PFAS exposure,

• produce information that public health professionals can use to help communities affected by

PFAS, and

• inform future studies looking at the effect of PFAS exposure on human health.

Exposure assessment (EA) participants were

recruited among El Paso County residents

living near the Peterson Air Force Base who

received drinking water from the Security

Water District, western portions of the

Widefield Water Sanitation District, or

Security Mobile Home Park that had PFAS

levels above state or federal guidelines. For

purposes of this report, we refer to the

“Security-Widefield EA” to describe the EA

conducted in this area. For more

information and a map of the area see the

“Methods” section of the report.

that resist grease, water, and oil [Buck et al. 2011; Gluge et al. 2020; Wang et al. 2017]. Exposure to

PFAS has been associated with increased cholesterol, decreased vaccine response in children, changes in

liver enzymes, small decreases in infant birth weights, increased risk of high blood pressure or pre-

eclampsia in pregnant women, and increased risk of kidney and testicular cancer [ATSDR 2021].

There are thousands of different PFAS. This assessment discusses some of the most commonly studied

PFAS, which include perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS),

perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA),

and perfluoroundecanoic acid (PFUnA). The manufacture and import of PFOA, precursor chemicals that

can break down to PFOA, and related higher homologue chemicals, have been mostly phased out in the

United States. However, existing stocks of PFOA might still be used, and there might be PFOA in some

imported articles. PFOS manufacture in the United States has not been reported to the EPA since 2002,

however, there are some limited ongoing uses of PFOS. These PFAS with long perfluoroalkyl chains are

no longer produced in the United States because of concerns over their high persistence, tendency to

bioaccumulate, and potential risks to human health and the environment. Other countries may still

manufacture and use them, but U.S. manufacturers have replaced these compounds with shorter

chained PFAS, or chemicals with alternative chemistries, such as GenX (HFPO-DA), which typically have

shorter biological half-lives. Some of the PFAS discussed in this report, such as N-methyl

perfluorooctanesulfonamidoacetic acid (MeFOSAA), are considered precursors that can degrade in the

environment or in people to other PFAS [ATSDR 2021; Wang et al. 2017].

PFAS do not occur naturally but are widespread in the environment. PFAS can be released into the

environment during their production, use, or disposal. PFAS have been found in soil, sediment, water,

animal and plant life, and air. Most PFAS (including PFOA, PFOS, PFHxS, and PFNA) are either very

resistant to breaking down or degrade into other PFAS that do not degrade further. Certain PFAS will

therefore remain in the environment indefinitely. Most people in the United States have been exposed

to PFAS. At least one PFAS was detected in more than 99% of NHANES samples (1999-2000 survey cycle)

[Calafat et al. 2007a]. Exposure can occur via contaminated drinking water for which ingestion is

believed to be the primary exposure route. Studies have shown that showering, bathing, and swimming

in water containing PFAS at levels seen in Security-Widefield are not expected to be an important

contributor to PFAS exposure relative to the contribution from drinking water [Sunderland 2019].

ATSDR’s PFAS EAs focused on communities with known exposures via contaminated drinking water.

However, residents may have had additional exposures to PFAS, such as the following [Sunderland

2019]:

• eating food packaged in materials containing PFAS (e.g., popcorn bags, fast food containers,

pizza boxes)

• eating fish or shellfish caught in PFAS-contaminated waters

• using consumer products such as stain-resistant carpeting and water-repellent clothing

• eating garden vegetables grown with PFAS-contaminated water or soil

• accidentally swallowing PFAS-contaminated soil

• drinking infant formula mixed with PFAS-contaminated water

• consuming breastmilk from women exposed to PFAS

• gestational exposure to PFAS

• working in industries that manufacture, process, or use products containing PFAS

• background exposure to PFAS due to their ubiquitous nature.

ATSDR asked study participants about these types of potential exposures to evaluate whether these

exposures might influence PFAS levels in the EA communities.

After PFAS enter the human body, some PFAS can remain there for a long time. Most studies estimate a

half-life of PFHxS between 4.7 and 8.5 years, although some have estimated half-lives as long as 35 years

[ATSDR 2021]. Most half-life estimates for PFOS are between 3.3 and 7.4 years, with a maximum of 27

years [ATSDR 2021]. For PFOA, most studies estimate the half-life between 2.1 and 3.9 years with a

maximum of 10.1 years [ATSDR 2021].

The body of science about PFAS exposure and health effects is growing rapidly. Some, but not all,

scientific studies have shown that exposure to certain PFAS may be linked to harmful health effects.

While this EA does not examine specific health outcomes associated with PFAS exposure, EA findings

might help inform future studies on how PFAS exposure affects human health.

Why Security-Widefield?

Security-Widefield was one of several sites located near military installations with identified PFAS

drinking water contamination from use of products such as aqueous film forming foam (AFFF). When

selecting EA sites, ATSDR considered the extent of PFOA and PFOS contamination in drinking water

supplies, the duration over which exposure may have occurred, and the number of potentially affected

residents.

PFAS and precursors that degrade to other compounds measured in this EA were used in historical AFFF

formulations. Two types of PFAS containing AFFF were manufactured before 2016 [ITRC 2020]. Both

formulations contained PFAS or PFAS precursors, the use of which resulted in the release of PFOS,

PFHxS, PFOA, and PFHxA into the environment. Possibly as early as the 1970s, Peterson Air Force Base

(the Base) used AFFF containing PFAS for its firefighter training (AFCEC 2018). Over time, the PFAS from

the AFFF moved off site in groundwater and contaminated nearby public drinking water supply wells.

When PFAS first entered Security-Widefield’s public water systems is not known. These substances were

first detected in municipal wells near the Base in 2013 and 2014, through testing conducted for the U.S.

Environmental Protection Agency’s (EPA’s) Third Unregulated Contaminant Monitoring Rule (UCMR 3)

[EPA 2017]. The rule required testing for six PFAS. The levels measured in the Security Water District

(WD) and Widefield Water and Sanitation District (WSD) water systems during UCMR 3 were above

EPA’s provisional health advisory, which at the time was 400 parts per trillion (ppt) for PFOA and 200 ppt

for PFOS.

• In the Security WD system, PFHxS, PFOS, or PFOA were detected in 36 out of 38 samples taken

between January 14 and August 11 of 2014. Wells from both the eastern and western parts of

the system exceeded EPA’s provisional health advisory, and the highest PFOA+PFOS

concentration was 1,370 ppt in a well in the eastern part of the system. However, water from

this well fed into a tank and mixed with uncontaminated surface water prior to entering the

distribution system. According to Security WD engineers, on average, the groundwater would

have been diluted with uncontaminated surface water by approximately 90 percent. The highest

measurements of finished individual PFAS in finished water (water consumed by customers) in

the Security WD system were 590 ppt for PFHxS, 210 ppt for PFOS, and 90 ppt for PFOA.

PFHxS data were not available for all sites evaluated so were not considered in the site selection process even

though water contaminated by AFFF often has higher concentrations of PFHxS than PFOA or PFOS.

• In the Widefield WSD system, PFHxS, PFOS, or PFOA were detected in 11 out of 17 samples

taken between November 12, 2013, and August 11, 2014. PFOA+PFOS exceeded EPA’s health

advisory in five samples with a maximum concentration of 246 ppt at a well in the western part

of the system. Water that entered the eastern part of the Widefield WSD distribution system

was less contaminated. The highest measurements of individual PFAS in the Widefield WSD

system, detected in western portions of the system, were 330 ppt for PFHxS, 210 ppt for PFOS,

and 48 ppt for PFOA.

In 2016, EPA issued a lifetime health advisory (HA) for the sum of PFOA and PFOS levels in drinking

water (70 ppt). In 2016 and 2017 (CDPHE, 2019) the Colorado Department of Public Health and

Environment (CDPHE) reported the results of PFAS testing in water supplies across El Paso County. The

CDPHE data confirmed PFAS contamination throughout the Security WD distribution system and in the

western parts of the Widefield WSD system. The CDPHE data showed exceedances of the EPA’s HA in a

third system, the Security Mobile Home Park (MHP).

• In February 2016, PFAS was detected in an active groundwater well within the Security MHP

system at levels of 70 ppt for PFOS and 33 ppt for PFOA.

Between January and November of 2016, Security WD and Widefield WSD inactivated their

contaminated groundwater wells and shifted to uncontaminated surface water sources. In 2017,

Widefield WSD installed an ion exchange system to treat PFAS in water from its contaminated wells.

Security WD currently uses uncontaminated surface water sources. Residents of Security MHP were

provided bottled water beginning in the summer of 2016 until a treatment system was installed in

November of 2017. By 2016, all three systems had taken active measures to reduce PFAS exposure to

customers.

The information available to ATSDR indicates that, when the EA was conducted in 2020, drinking water

supplies in Security-Widefield met or were below the EPA’s HA for PFAS in drinking water.

Methods

ATSDR’s PFAS EA protocol [ATSDR 2019a] details the approaches used to recruit participants, collect

samples, administer exposure history questionnaires, and evaluate data. This section briefly describes

how those methods were applied to the Security-Widefield EA.

Sampling Frame

This EA targeted a specific geographic area, called the sampling frame or sampling area. The sampling

frame for this EA was the area served by the drinking water systems of Security WD, Security MHP, and

the western portion of the Widefield WSD (see Figure 1

). Based on a review of El Paso County land

parcel data, ATSDR determined that 10,783 households in the sampling frame were connected to the

Security-Widefield water supplies. These households formed the sampling frame from which households

were randomly selected for recruitment. Households with private wells were not eligible for

participation. Private well owners living in the area affected by PFAS should consider having their wells

tested for PFAS if testing has not been conducted before. To learn more about testing wells for PFAS

visit:

https://www.elpasocountyhealth.org/news/news-release/2019/resources-for-pfc-water-

contamination-and-testing.

Figure 1. Sampling frame for the Security-Widefield Exposure Assessment

Participant Eligibility

Security-Widefield residents who were randomly selected to participate and met the following criteria

were eligible to participate in the EA:

• Lived within the sampling frame (i.e., Security-Widefield households in the affected area shown

in Figure 1

) for at least one year before November 10, 2016, which is when Security-Widefield

reduced PFAS drinking water concentrations below EPA’s HA in all three water systems.

• Were at least 3 years old at the time of recruitment. This age criterion was used because

national reference values are not available children under the age of three.

• Did not have bleeding disorders and were not anemic, unless they confirmed with their doctor

the ability to safely provide a blood sample.

People potentially exposed to PFAS occupationally, such as firefighters, active-duty military, and

veterans were able to participate if they met the three eligibility criteria. Participants did not receive

incentives and paid no costs to participate.

Participant Recruitment

ATSDR randomly selected 3,000 households in the

sampling frame for recruitment. This number was chosen

to attempt to achieve the protocol recruitment target of

395 participants. Every household had an equal chance of

being selected, and all members of randomly selected

households who met eligibility criteria were invited to

participate. This type of recruitment, called a one-stage

cluster sampling design, means that a single household

may have multiple participants.

Recruitment was done through mailings, phone calls, and in-person visits to households that could not

be reached by phone. Each household for which ATSDR had a phone number received a minimum of

three recruitment call attempts. In each attempt, ATSDR called all working phone numbers (cell phone

and landline) associated with a household. For calls that went to voicemail, ATSDR staff left messages

encouraging residents to call back to schedule appointments. Door-to-door recruitment occurred after

each household had received an initial outreach letter and at least one recruitment call attempt.

Results from the randomly selected participants can provide information about community-level

exposure. Had ATSDR accepted volunteers, results could not be used to estimate exposure across the

Security-Widefield sampling frame. After two waves of recruitment (initially reaching out to 1,162

households and later reaching out to an additional 1,838 households), 384 residents from 200

households scheduled appointments for biological sampling and questionnaire completion.

ATSDR attempted to recruit 10% of the participating households for environmental sampling. ATSDR

invited 30 households, and 20 households scheduled environmental sampling appointments.

Data Collection and Analysis

The Security-Widefield EA involved collection of three types of data: questionnaires, biological samples

(blood and urine), and environmental samples (tap water and household dust). The ATSDR project team

collected biological samples at the Security Village Fire Station between September 15 and September

Measuring PFAS in the blood of people

from randomly selected households

allowed ATSDR to estimate exposure

to PFAS from public drinking water for

the entire community (the sampling

frame) in the affected area, even those

who were not tested.

28, 2020. During this same time frame, ATSDR administered questionnaires over the phone and

collected environmental samples in a subset of randomly chosen participant homes. All data met the

stringent quality control requirements for sample collection and analysis.

Before any data collection, ATSDR obtained written consent from the participants. The purpose of the

consent process was to ensure participants were fully aware of the purpose of the EA, sample collection

procedures, benefits and risks of participating, and privacy protections. Copies of consent forms are

included in the PFAS EA Protocol.

ATSDR project staff handled all data collected in accordance with the Standard Operating Procedures of

PFAS Exposure Assessment Data Management [ATSDR 2019b]. These procedures have very strict

requirements for handling any personally identifiable information. ATSDR project staff protected this

information to the extent required by federal and Colorado law. All signed consent forms were mailed to

and are securely archived at ATSDR headquarters. Participant responses to phone questionnaires were

logged directly into ATSDR’s secure data network. All information provided by participants was kept

confidential, and no personally identifiable information appears in any of ATSDR’s public reports for this

site.

Table 1

, at the end of this section, provides more details on the number of participants enrolled and the

final number of samples collected during this EA. Table 2 lists the PFAS measured in the EA’s biological

and environmental samples.

Biological Sampling and Questionnaire Administration

Of the 384 residents who scheduled data collection appointments, 359 (93%) participated in the EA.

ATSDR administered exposure history questionnaires to 355 EA participants: 321 for adults 18 and older,

and 34 for children between the ages of 3 and 17. Four participants that provided blood samples did not

complete a questionnaire. ATSDR used one questionnaire for adults and another for children. Both

addressed topics relevant to PFAS exposure, such as residential and work histories, drinking water

habits, and use of PFAS-containing consumer products.

A phlebotomist collected blood samples from all 359 participants. ATSDR processed the blood samples

in the field, aliquoting the serum portion of the blood.

After the sampling was complete and upon further review of each participant’s residential history,

ATSDR determined that 13 participants had not lived in the sampling frame for at least one full year

before November 10, 2016, and therefore were not eligible for the study. Questionnaire and biological

data for these participants were excluded from the data evaluation, but ATSDR sent them their

individual results. This means that a total of 346 blood samples (318 adults and 28 children) were

considered in the community exposure summary. These samples were collected from participants

residing in 188 unique households. This represents a household participation rate of 6.3% (i.e., 6.3% of

the 3,000 recruited households had at least one person participate in the EA).

Urine samples were collected from 354 participants (324 adults and 30 children). Per the EA protocol,

10% of the urine samples were randomly selected for initial analysis. ATSDR randomly selected 36

samples for analysis. These samples were collected from participants (34 adults and 2 child) who resided

in 36 unique households.

CDC’s National Center for Environmental Health laboratory analyzed the serum portion of blood and

urine samples for the suite of PFAS measured in the 2015–2016 National Health and Nutrition

Examination Survey (NHANES) [CDC 2019]. As part of NHANES, CDC takes biological samples and tests

them for chemicals, including PFAS, from a representative sample of 5,000 people across the country

during each two-year cycle. All laboratory analyses followed established procedures for quality

assurance and control according to the Center’s methodology.

During the consent process, participants were given the option to allow ATSDR to store biological

samples for potential future PFAS analysis. Blood and urine samples from participants who provided this

consent are being stored frozen at CDC for potential future analysis.

Environmental Sampling

ATSDR collected tap water and dust samples from 18 of the 20 households that had initially scheduled

appointments. Two households were unavailable to complete their environmental sampling

appointment. At each participating household, ATSDR collected a drinking water sample from the

kitchen tap. If point-of-use filtration was in place, ATSDR project staff attempted to collect a sample

before and after filtration. Tap water samples were collected and analyzed in accordance with EPA’s

Method 537.1: Determination of Selected Per- and Polyfluorinated Alkyl Substances in Drinking Water by

Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry [Shoemaker and

Tettenhorst 2018].

Project staff also collected a composite dust sample from the floor at a minimum of three locations

inside each selected home: the primary living space as identified by the homeowner (e.g., living room,

family room, television room), the kitchen, and the bedroom in which participants reported spending

the most time. Dust collection was intended to generate more information about the contribution of

non-drinking-water exposures to overall PFAS exposure. Participants were instructed not to vacuum

carpeting or sweep floors for five days prior to the scheduled visit. Adapting methods described in Scher

et al. [2018], ATSDR collected dust samples using a high-volume air sampler connected to an open-faced

37 millimeter filter cassette with an 0.8 micron filter. A wooden 2 square foot (ft

) sampling template

was used to mark off each sampling area. ATSDR project staff attempted to collect at least 1 gram of

dust in the open-faced cassettes from each home by vacuuming the same 2 ft

surface at least four

times with the cassette (vertically, horizontally, and in circles). Samples were taken preferentially from

mats, carpets, and area rugs. Household dust samples were analyzed in accordance with SGS AXYS

Method MLA-110 (revision 01, version 06), Analytical Procedure for the Analysis of Per- and

Polyfluoroalkyl Substances (PFAS) in Aqueous Samples, Solids and Solvent Extracts by LC-MS/MS [SGS

AXYS 2019].

The environmental samples collected during the EA were consumed in the analytical process and are not

available for potential future analysis.

Table 1. Summary of recruitment and data collection efforts

Recruitment

Households invited to participate by mail 3,000

Wave 1 of recruitment 1,162

Wave 2 of recruitment 1,838

Households reached by mail 2,567

Households reached by phone 1,147

Household door-to-door visits 2,640

Biological sampling:

Individuals enrolled 384

Households enrolled 200

Environmental sampling:

Households invited 30

Households enrolled 20

Data Collection

Completed questionnaires 355

Adults 321

Children 34

Blood samples

Included in community statistics (188 households) 346

Adults 318

Children 28

Urine samples

Collected 354

Adults

324

Children 30

Included in community statistics (36 households) 36

Adults 34

Children 2

Dust samples collected and analyzed (one composite

sample per household)

Tap water samples collected and analyzed (18 households) 34

Filtered 17

Unfiltered 17

Table 2. List of PFAS measured for in blood, urine, tap water, and dust

PFAS

Abbreviation

PFAS Chemical Name

Measured

in Blood?

Measured

in Urine?

Measured

in Water?

Measured

in Dust?

PFBS perfluorobutane sulfonic acid   

PFPeS perfluoropentane sulfonic acid 

PFHxS perfluorohexane sulfonic acid    

PFHpS perfluoroheptane sulfonic acid 

PFOS perfluorooctane sulfonic acid    

n-PFOS sodium perfluoro-1-octanesulfonate  

Sm-PFOS

mixture of sodium perfluoro-5-methylheptane

sulfonate isomers

 

PFNS perfluorononane sulfonic acid



PFDS perfluorodecane sulfonic acid 

PFDoS perfluorododecanesulfonate 

PFBA perfluorobutanoic acid  

PFPeA perfluoropentanoic acid  

PFHxA perfluorohexanoic acid   

PFHpA perfluoroheptanoic acid   

PFOA perfluorooctanoic acid    

n-PFOA ammonium perfluorooctanoate  

Sb-PFOA

mixture of perfluoro-5-methylheptanoic acid

isomers

 

PFNA perfluorononanoic acid    

PFDA perfluorodecanoic acid

   

PFUnA perfluoroundecanoic acid    

PFDoA perfluorododecanoic acid  

PFTrA perfluorotridecanoic acid  

PFTA perfluorotetradecanoic acid  

PFOSA perfluorooctanesulfonamide



N-MeFOSA N-methylperfluorooctanesulfonamide 

MeFOSAA

N-methyl perfluorooctanesulfonamidoacetic

acid

  

N-MeFOSE N-methylperfluorooctanesulfonamidoethanol 

N-EtFOSA N-ethylperfluorooctanesulfonamide 

N-EtFOSAA N-ethyl perfluorooctanesulfonamidoacetic acid  

N-EtFOSE N-ethylperfluorooctanesulfonamidoethanol



FtS 4:2 fluorotelomer sulfonic acid 4:2 

FtS 6:2 fluorotelomer sulfonic acid 6:2 

FtS 8:2 fluorotelomer sulfonic acid 8:2 

HFPO-DA

(GenX)

hexafluoropropylene oxide dimer acid   

DONA 4,8-dioxa-3H-perfluorononanoic acid   

9Cl-PF3ONS

9-chlorohexadecafluoro-3-oxanone-1-sulfonic

acid

  

11Cl-PF3OUdS

11-chloroeicosafluoro-3-oxaundecane-1-

sulfonic acid

 

Statistical Analysis

The EA Protocol describes the statistical methods

used. Briefly, the data objectives of this EA were to

(1) estimate geometric mean concentrations of PFAS

in the sampling frame population (with a precision

target of at least 15% and a 5% level of significance

for PFOS), (2) compare community level data to

national levels, and (3) explore relationships

between questionnaire data and measured biological

and environmental data.

ATSDR processed the PFAS sampling results in two

ways before performing statistical analyses:

• First, ATSDR substituted all non-detect

observations with a value equal to the limit

of detection (LOD) divided by the square root

of 2. (A non-detect result means the sample

did not contain enough PFAS to be reliably

measured by this project’s highly sensitive

laboratory methods.) This substitution

method is consistent with that applied in

CDC’s NHANES. Note that Appendix B

provides the results of a sensitivity analysis

exploring alternate substitution approaches.

• Second, ATSDR calculated the total PFOA and

total PFOS concentrations measured in each

blood and urine sample. The laboratory

reports two different measurements for

PFOA and PFOS. For PFOA, the laboratory

reports the amount of branched PFOA (Sb-

PFOA) measured in the sample separate

from the amount of linear PFOA (n-PFOA) in

the same sample. ATSDR summed these

values and performed statistical analyses

using total PFOA results. Similarly, ATSDR

calculated total PFOS by summing the linear

PFOS (n-PFOS) and branched PFOS (Sm-

PFOS) concentrations. These same

summation methods are applied to NHANES

data.

For blood and urine, ATSDR first calculated summary

statistics for each PFAS (i.e., frequency of detection,

maximum detected concentration, geometric mean,

95% confidence intervals around the geometric

mean, and 25

, 50

[median], 75

, 90

, and 95

percentiles). The protocol specified that geometric

Statistical Terms

Geometric mean: The geometric mean is a

type of average and provides an estimate of

the central point of a set of numbers. It is

often used for environmental data that

exhibit a skewed distribution (e.g., a dataset

with several values that are much higher

than the rest of the results). The geometric

mean is less influenced by high values than

an arithmetic mean.

Percentiles (25th, 50th, 75th, 90th, 95th): A

percentile provides additional information

about the distribution of a dataset and

represents the value below which a certain

percentage of the data fall. For example, a

95th percentile of 25 micrograms per liter

(µg/L) indicates that 95% of results fall below

this concentration.

Confidence intervals: A confidence interval

defines a range of values that's likely to

include a specific value with a certain degree

of confidence (probability). It provides a

measure of how much uncertainty there is

with any particular statistic In this EA, ATSDR

estimated geometric means for the PFAS

blood levels measured among study

participants. The 95% confidence interval

around the geometric mean represents the

range within which the true population

mean is expected to lie. More specifically, if

we hypothetically repeated the study 100

times, 95 times out of 100 the mean of the

sampling frame population would fall within

this range.

Precision: Precision provides information on

the reproducibility of a study and is

associated with sample size. The larger the

sample size the higher the precision. In the

context of this EA, precision was estimated

based on the width of confidence intervals

around the geometric mean. A wide

confidence interval indicates low precision

while a narrow confidence interval suggests

high precision.

means would be calculated if >=60% of samples had detections. Geometric means were calculated as

the measures of central tendency because of the lognormal distribution of blood and urine

measurements. Note that many of the statistics could not be calculated for urine due to the low

detection frequency.

One of the objectives of this EA was to estimate community-level exposures. While random recruitment

at the household level helps allow for such an estimation, ATSDR evaluated demographic differences

between the Security-Widefield EA participants and all residents in the sampling frame. This was done

for age, race, and ethnicity using a two-sample test for equality of proportions. To correct for

participation bias, ATSDR also calculated geometric means adjusted to the age distribution of the

sampling frame population using 2010 Census block data.

ATSDR compared community-level statistics for PFAS in blood to national PFAS data reported by CDC in

the 2015–2016 NHANES (i.e., for the EA sample population 12 years of age and older). To control for

differences in the age distribution, the EA geometric

means were adjusted to the age distribution of the U.S.

population during NHANES 2015–2016. Note that

NHANES 2017-2018 data were not available at the time

this report was originally drafted. For urine, ATSDR

compared community-level data to national-level data

from the 2013–2014 NHANES compiled by Calafat et al.

[2019], the only nationally representative data available

for PFAS in urine. ATSDR relied on two sample t-tests (on

log-transformed data) for these comparisons, using a p-

value of less than 0.05 to identify statistically significant

differences.

ATSDR then used information gathered in the exposure questionnaire to understand and quantify how

demographic data and other exposure characteristics relate to PFAS measurements in blood. For this,

ATSDR relied on self-reported information, such as age, race/ethnicity, sex, length of residency in the

sampling frame, tap water and food consumption patterns, and work/school history. All numerical

responses were treated as continuous variables. In some cases, categorical variables were collapsed

when there were too few responses (<10) in a given category. In order to explore sex-specific

associations (e.g., women having biological children [yes/no], having breastfed children [yes/no],

duration of breastfeeding), ATSDR also evaluated multivariate models for males and females only. For all

univariate and multivariate analyses, ATSDR modeled log transformed (logarithm base 10 or log

) blood

PFAS concentrations.

ATSDR did not conduct detailed statistical analyses for urine data because of low frequencies of

detection. ATSDR analyzed a subset of urine samples and found that, for all PFAS, the frequency of

detection was < 60%. The protocol specified that all urine samples would be analyzed if the geometric

mean calculated for any site exceeded the 95

percentile from NHANES. The protocol specified that

geometric means would be calculated if ≥60% of samples had detections, and the rest of the samples

would be analyzed if the calculated geometric mean exceeded the NHANES 95

percentile. Since no

PFAS were detected in 60% or more of the analyzed samples, no geometric means were calculated for

any PFAS in urine and ATSDR did not analyze the remainder of the urine samples. The 95

percentile

concentration for PFBA, was below the detection limit.

A p-value helps determine the

significance of the results of a statistical

test, such as the difference between

two means. The lower the p-value the

more likely the observed difference is

not due chance alone. In this report, a p-

value of less than 0.05 (p<0.05) is

described as statistically significant. This

level specifies less than a 5% probability

of being due to chance alone.

For tap water data, ATSDR compared PFAS levels measured with and without filtration to EPA’s HA value

(70 ppt for the sum of PFOA and PFOS). For dust, ATSDR calculated summary statistics and compared

results to those in selected peer-reviewed literature. ATSDR also evaluated correlations between PFAS

levels measured in household dust and blood collected from participants residing in homes where dust

samples were collected.

To account for the one-stage cluster design, ATSDR conducted all statistical analyses in SAS (release 9.4,

SAS Institute, Cary, NC) using complex survey procedures (e.g., SURVEYMEANS, SURVEYREG). To do this,

ATSDR assigned household IDs to all participants and calculated summary statistics while accounting for

clustering at the household level. For blood results across all EA participants, intra-cluster correlation

coefficients ranged from 0.26 to 0.81, suggesting weak to strong correlation of PFAS blood levels within

a household. Appendix B provides more information on clustering, as well as further details on the

statistical methods used for this EA and how results from this EA compared to the assumptions used to

estimate the target sample size of 395 participants.

Results

This section summarizes EA findings. It first profiles the Security-Widefield EA participants and compares

their demographics to the entire sampling frame, then reviews the blood, urine, tap water, and

household dust measurements that ATSDR collected. Those reviews use exposure history questionnaire

data to provide further context on the measurements. (The next section, “Discussion,” further evaluates

the observed trends using insights from the broader scientific literature on PFAS drinking water

exposures.)

Most analyses in this section reflect the entire Security-Widefield EA participant population, but some

pertain to subsets of that population. This is because separate exposure history questionnaires were

administered to adults and children and because some questions on the adult questionnaire only

applied to females.

Profile of Security-Widefield (El Paso County) EA Participants

EA participants responded to exposure history questions and reported information on many

characteristics, such as their age, sex, race/ethnicity, residential and occupational history, and drinking

water consumption. Table 3

summarizes this information.

Table 3. Characteristics of Security-Widefield EA participants

Characteristics

Count of EA

Participants (n)*

Percent of EA

Participants (%)

‡

Adults and children combined

Age (years) (mean = 53.4)

<18 28 8.1

18 to <50 97 28

50+ 221 64

Sex

Male 153 44

Female 193 56

Race and ethnicity

†

White, non-Hispanic 239 71

non-White or Hispanic 99 29

Adults only

Years lived at current address (mean = 20.8)

<10 80 25

10 to <20 82 26

20 to <30 77 24

30+ 79 25

Current primary drinking water source

Public water system 217 68

Bottled water 101 32

Average tap water consumption while living at current home (8-

ounce cups per day)

(mean = 6.4)

0 45 14

>0 to <2 13 4.1

2 to <4 40 13

4 to <6 60 19

6 to <8 44 14

8+ 114 36

Current use of treatment or filtration device

One or more filter/treatment device(s) 190 60

None 128 40

Occupational exposures to PFAS in the past 20 Years

One or more occupational exposure(s) 41 13

None 227 87

* The sums of participants for different fields in this table do not always add up to expected values, because not

every participant answered corresponding questions during the questionnaire.

†

ATSDR collapsed categories for race and ethnicity for all analyses because of the few responses across

categories.

‡

The sums of percentages for different fields in this table do not always add up to 100%, because not every

participant answered corresponding questions during the questionnaire and because of rounding

The average age of EA participants was 53.4 years, and 71% of the participants identified themselves as

White, non-Hispanic. Of EA participants, 56% identified as female, 44% identified as male, and 92% were

adults, aged 18 years or older. The age cutoff is important because adults were administered a different

exposure history questionnaire with more detailed questions. Among the adult participants, 75%

reported living in their current homes for more than 10 years.

Adults were also asked about their current primary source of drinking water: 68% said public water

system (Security WD, Widefield WSD, or Security MHP), and 32% said bottled water. Adults reported

drinking an average of 6.4 8-ounce cups of water a day at home, and 60% said they currently use some

type of filtering or treatment device for their drinking water. Examples include filters on refrigerators,

pitchers, and faucets; whole-house carbon filtration systems; and reverse osmosis treatment systems.

The questionnaire asked adults for their occupational histories over the past 20 years; 13% reported

holding one or more jobs with potential PFAS exposures (e.g., firefighting, military, aviation).

Comparison of Security-Widefield EA Participants’ Demographics to Sampling

Frame Demographics

This EA was designed to estimate PFAS levels in blood that were generalizable to the sampling frame as

a whole (i.e., Security-Widefield households in the affected area shown in Figure 1). The recruitment

method used for this EA ensures the absence of selection bias—that is, everyone in the sampling frame

had an equal chance of being chosen to participate. However, ATSDR also explored the potential for

participation bias—that is, substantive differences between those who chose to participate and those

who did not.

ATSDR used 2010 Census data (Table 4) [USCB 2010] to compare the EA participants’ demographic

profile with the profile of all residents in the sampling frame. The comparison revealed the following:

• Age distribution. The EA participants included a higher proportion of older adults (age 50+

years), a lower proportion of younger adults (18–50 years), and a lower proportion of children

(age <18 years) than the sampling frame population (Table 4). Specifically, 64% of the EA

participants reported being 50 or older, but 29% of the sampling frame population falls in this

age range (ATSDR chose 50 years as a cutoff for older and younger adults based on the median

age of menopause in the United States, which may affect exposure profiles). Similarly, 28% of

the EA participants reported being 18–50, but 43% of the sampling frame population falls in that

age range. Finally, 8.1% of the EA participants reported being <18 years, but 28% of the

sampling frame population falls in that age range.

• Race/ethnicity. Among the race/ethnicity characteristics, only the percent of residents who

identify as White and more than one race showed a significant difference between the EA

participants and the sampling frame population (Table 4). Specifically, the EA population had

statistically more White participants (79%) than the sampling frame population (74%) and fewer

participants who identified as more than one race (3.5%) than the sampling frame (8.3%). For

this comparison, combined race and ethnicity were not available at the block level from the

Census. Therefore, only ethnicity and the race categories of White, Black, and More than one

race were compared because of the small number of respondents in other categories.

The effect of age on blood levels and its implications on community statistics is further explored

throughout this report. Refer to the “Discussion” section for ATSDR’s assessment of how these

demographic differences influence data interpretations.

Table 4. Demographic comparison of EA participants and the sampling frame population

Demographics

Number of

Participants

(n)*

Percent of

Participants

(%)

Sampling

Frame

Distribution

(%)

†

p-Value

‡

Age Group (years)

<18 28 8.1 28.1 <0.001

18–50 97 28.0 43.2 <0.001

50+ 221 63.9 28.7 <0.001

Race

White 275 79.5 73.7 0.017

Black or African American 28 8.1 9.2 0.52

Am. Indian & AK Native <10 — 1.1 —

Asian <10 — 2.8 —

Nat. Hawaiian/Pacific Islander <10 — 0.88 —

More than one race 12 3.5 8.3 0.0016

Ethnicity

Hispanic or Latino (of any race) 57 16.5 18.5 0.38

Counts may not sum to total because participants may have refused to answer questions. Counts are not shown

for categories with fewer than 10 participants.

†

Sampling frame data are based on the 2010 U.S. Census. Demographic characteristics of the sampling frame

may have changed between 2010 and 2020, the time of this EA.

‡

Two-sample test for equality of proportions with continuity correction comparing EA and 2010 Census data. A p-

value of less than 0.05 indicates a statistically significant difference between EA participants and all residents in

the sampling frame.

PFAS in Blood

This section summarizes PFAS levels that ATSDR measured

from the 346 blood samples provided by eligible participants.

Results are summarized in tables and ‘box and whisker’ plots

(see text box).

Unadjusted Community Statistics for PFAS in Blood

ATSDR first calculated the geometric mean levels of PFAS

without accounting for the possible effect of age. Table 5

summarizes results for the seven PFAS measured in Security-

Widefield EA participants’ blood for all ages. Six of the seven

PFAS—PFHxS, PFOS, PFOA, PFNA, PFDA, and MeFOSAA—

were detected in more than 67% of the blood samples.

ATSDR’s statistical analyses throughout this section focus on

these six chemicals, and

Figure 2 shows the distributions of

the individual measurements on a log

scale. The log

scale

allows for more easily visualizing the wide range of serum

concentrations as it uses equal spacing for each factor of 10

increase. The PFAS found at highest levels were PFHxS

How to read a box and whisker plot:

A box and whisker plot illustrates a

summary of the data using different

statistical measures. See the image

below for how to interpret the

figures throughout this report.

(geometric mean = 10.6 micrograms per liter (or µg/L)), PFOS (6.22 µg/L), and PFOA (2.14 µg/L).

One PFAS—PFUnA—was detected in fewer than 60% of the samples. Low frequency of detection for

PFUnA is consistent with NHANES data. Detailed statistics are not included for this chemical, and

concentration percentiles (25

, 50

, 75

, 90

, 95

) are shown only for measurements above the LOD.

The precision of geometric mean estimates for this EA for all PFAS ranged from 0.2% to 16% depending

on the PFAS (Appendix B, Table B2). Except for Sm-PFOS, these values are all below the desired precision

of 15% used to determine the target sample size for this EA. The collected data met the precision target

specified in the EA protocol.

Table 5. Community statistics for PFAS in blood in micrograms per liter

PFAS

FOD

(%)

Max

Geometric

Mean

95% CI for

Geometric

Mean

Percentiles

(Median)

PFHxS 100 138.2 10.6 9.19–12.3 4.93 11.6 24.4 43.2 55.9

PFOS NA* 42.5 6.22 5.53–6.99 3.65 6.50 11.5 18.1 23.8

PFOA NA* 16.8 2.14 1.96–2.34 1.28 2.18 3.45 5.25 6.41

PFNA 95.1 2.4 0.286 0.262–0.312 0.135 0.243 0.390 0.680 0.845

PFDA 68.5 0.9 0.123 0.113–0.133 NA

†

0.138 0.241 0.361

PFUnA 41.3 1.6 NA

‡

†

0.138 0.183

MeFOSAA 67.1 2.3 0.134 0.121–0.148 NA

†

0.169 0.293 0.557

FOD = frequency of detection, CI = confidence interval, NA = not applicable

PFOA and PFOS are calculated sums of branched and linear subsets and are not measured directly. Linear PFOA

was detected in 99.4% of samples with a geometric mean of 2.04 micrograms per liter (µg/L); branched PFOA

was detected in 0.3% of samples. Linear PFOS was detected in 99.1% of samples with a geometric mean of 3.98

µg/L; branched PFOS was detected in 99.4% of samples, with a geometric mean of 2.11 µg/L.

†

Percentile is below the LOD.

‡

Per the EA protocol, geometric means were not calculated for PFAS detected in less than 60% of samples.

Figure 2. Distribution of PFAS blood levels (log scale)

Community Statistics for PFAS in Blood Age-Adjusted to the Sampling Frame

Since the demographic profile comparison reported above showed that EA participants were

significantly older than the sampling frame as a whole, ATSDR also calculated geometric means that

were age-adjusted to the sampling frame population based on 2010 Census data for comparison. Age-

adjusted geometric means correct for the participation bias discussed earlier and are more generalizable

to the sampling frame community. Table 6

shows that age-adjusted blood geometric means for all PFAS

are lower than unadjusted values. Of the three PFAS with the highest concentration (PFHxS, PFOS, and

PFOA), age-adjusted geometric means are between 20% and 35% lower than unadjusted values. The

lower values for age-adjusted geometric means reported here are consistent with older adults having

higher blood PFAS levels than younger adults. The effect of age and the implications of these age-

adjusted statistics are further discussed throughout this report.

Table 6. Geometric means for PFAS in blood in micrograms per liter, unadjusted and age-

adjusted to the sampling frame

Unadjusted Age-Adjusted to Sampling Frame

PFAS

Geometric

Mean

95% CI for Geometric

Mean

Geometric

Mean

95% CI for

Geometric Mean

PFHxS 10.6 9.19–12.3 6.88 5.70–8.29

PFOS 6.22 5.53–6.99 4.55 3.93–5.26

PFOA 2.14 1.96–2.34 1.72 1.54–1.93

PFNA 0.286 0.262–0.312 0.242 0.222–0.263

PFDA 0.123 0.113–0.133 0.118 0.108–0.130

PFUnA

‡

MeFOSAA 0.134 0.121–0.148 0.112 0.101–0.124

CI = confidence interval, NA = not applicable

* Per the EA protocol, ATSDR did not calculate geometric means for PFAS detected in less than 60% of samples.

Comparison of EA Participants’ PFAS Blood Levels to the National Population

This section compares PFAS levels among Security-Widefield EA participants to levels found in the U.S.

general population. To explore effects related to differences in the age distribution of EA participants vs.

the NHANES population, ATSDR calculated both unadjusted geometric means of all EA participants and

geometric means adjusted to the age distribution of the U.S. population in NHANES 2015–2016.

Table 7

shows the unadjusted comparison for the entire pool of EA participants to the data available

from NHANES, which are the geometric means for the 2015–2016 survey [CDC 2019]. For PFHxS, PFOS,

PFOA, unadjusted geometric mean blood levels among Security-Widefield EA participants were

statistically (p<0.05) higher than the national geometric mean. For PFNA and PFDA, the unadjusted

blood levels among Security-Widefield EA participants were statistically lower than the national

geometric mean. Per protocol, geometric means were not calculated during NHANES for PFAS detected

in less than 60% of samples, which included MeFOSAA. In this EA, MeFOSAA was detected in more than

60% of samples and geometric means were calculated.

Of the PFAS analyzed in blood, PFHxS levels had the largest elevations when compared to national

levels. The unadjusted geometric mean blood PFHxS level among Security-Widefield EA participants was

9.0 times the national level. Blood PFHxS levels were above the national geometric mean for 96% of EA

participants and above the NHANES 95

percentile for 75% of EA participants (Table 7). The unadjusted

geometric mean blood PFOS level among Security-Widefield EA participants was 1.3 times the national

level. Blood PFOS levels were above the national geometric mean for 65% of EA participants and above

the NHANES 95

percentile for 9.8% of EA participants. The unadjusted geometric mean blood PFOA

level among Security-Widefield EA participants was 1.4 times the national level. Blood PFOA levels were

above the national geometric mean for 69% of EA participants and above the NHANES 95

percentile for

19%.

On average, total PFOS measurements were composed of 65% linear PFOS (n-PFOS) and 35% branched

PFOS (Sm-PFOS). The proportion of n-PFOS found in EA participants’ blood is lower than that found in

standard PFOS products (76%–79%)

[Kärrman et al. 2007] but comparable to levels found in the blood of

the general U.S. population [CDC 2019]. Measurements of total PFOA were composed of 97% linear

PFOA (n-PFOA) and 3% branched PFOA (Sb-PFOA), which is also comparable to the proportions found in

the U.S. population [CDC 2019]. All remaining statistical analyses in this report focus on total PFOA and

total PFOS rather than treating the linear and branched isomers separately.

For this EA, ATSDR also calculated geometric means age-adjusted to the NHANES population. Because

the 2015–2016 NHANES survey does not report data for individuals under 12 years of age, these

geometric mean calculations are based on the 337 EA participants. Table 7 and Figure 3

show blood

PFAS geometric means adjusted to the NHANES population differ from unadjusted values. The adjusted

geometric mean blood PFHxS level among Security-Widefield EA participants was 6.8 times the national

level. The age-adjusted geometric mean blood PFOA level among Security-Widefield EA participants was

1.2 times the national level. Even when controlling for the age-distribution in the population, EA

participants had statistically higher blood levels of PFHxS and PFOA than the U.S. population. After

adjusting for age, blood levels of PFOS in EA participants were higher than the U.S. population, but the

difference was not statistically significant.

Table 7. Comparison of PFAS blood geometric means (GMs) and 95th percentiles in Security-

Widefield, Colorado, with the U.S. population (NHANES 2015–2016) in micrograms per liter

PFAS

NHANES GM

(CI)*

Security-

Widefield GM

(CI)

†

Unadjusted

Security-

Widefield GM

(CI)

†

: Age-

Adjusted to

NHANES 2015-

2016

Percent of

Security-

Widefield

Results

over

NHANES

GM (%)

NHANES

Percentile*

Security-

Widefield

Percentile

Percent of

Security-

Widefield

Results over

NHANES 95

Percentile (%)

PFHxS

1.18

(1.08–1.30)

10.6

(9.19–12.3)

p<0.001

8.08

(6.88–9.50)

p<0.001

96.0 4.90 55.9 75.1

PFOS

4.72

(4.40–5.07)

6.22

(5.53–6.99)

p<0.001

5.15

(4.48–5.91)

p=0.27

65.3 18.3 23.8 9.83

PFOA

1.56

(1.47–1.66)

2.14

(1.96–2.34)

p<0.001

1.82

(1.65–2.02)

p=0.009

68.5 4.17 6.41 18.8

PFNA

0.577

(0.535–0.623)

0.286

(0.262–0.312)

p<0.001

0.245

(0.223–0.270)

p<0.001

18.2 1.90 0.845 0.290

PFDA

0.154

(0.140–0.169)

0.123

(0.113–0.133)

p<0.001

0.119

(0.1.08–0.131)

p<0.001

33.0 0.700 0.361 1.16

PFUnA NA

‡

NA 0.400 0.183 1.45

MeFOSAA NA

‡

0.134

(0.121–0.148)

0.122

(0.110–0.136)

NA 0.600 0.556 4.62

CI = 95% confidence interval, NA = not applicable

Source: CDC 2019

†

P-values represent a t-test comparison between Security-Widefield GM and NHANES GM.

‡

Per the protocol, geometric means were not calculated for PFAS detected in less than 60% of samples.

No statistical comparison could be made with NHANES because NHANES did not calculate a geometric mean for

this PFAS because this PFAS was detected in less than 60% of NHANES samples.

Figure 3. EA average PFAS blood levels compared to national levels

Correlations Among PFAS in Blood

ATSDR also evaluated correlations between PFAS in blood (log

). This analysis determined whether any

PFAS tended to have similar patterns in the blood of Security-Widefield EA participants. ATSDR used

Pearson correlation coefficients (r) for this analysis. An r of 0 means two data sets are uncorrelated, and

an r of 1 means two data sets are exactly correlated (i.e., they rise and fall in proportional amounts). The

higher the coefficient, the closer the correlation. Table 8

shows the Pearson correlation coefficients for

the five most frequently detected PFAS.

PFHxS, PFOS, and PFOA blood levels showed the strongest correlations (Table 8). All pairings of these

chemicals had Pearson correlation coefficients relatively close to 1 (r = 0.71–0.73). On the other hand,

PFNA and PFDA were correlated with each other (r = 0.68) and had weak to moderate correlations with

other compounds (r = 0.13-0.61). MeFOSAA had weak or no correlations with all other compounds (r=-

0.038-0.29).

Table 8. Pearson correlation coefficients between PFAS in blood (log)

PFHxS PFOS PFOA PFNA PFDA MeFOSAA

PFHxS 1.00 0.72 0.73 0.32 0.13 0.22

PFOS 0.72 1.00 0.71 0.61 0.41 0.29

PFOA 0.73 0.71 1.00 0.57 0.35 0.19

PFNA 0.32 0.61 0.57 1.00 0.68 0.19

PFDA 0.13 0.41 0.35 0.68 1.00 -0.038*

MeFOSAA 0.22 0.29 0.19 0.19 -0.038* 1.00

* Correlations not significant, i.e., p>0.05.

PFAS Blood Levels by Demographics and Other Exposure Characteristics

This section examines how the demographic and exposure history information collected during the

questionnaire relates to blood PFAS levels. Since different questionnaires were administered to adult

and child participants, responses were analyzed separately. Additionally, some questions were

applicable only to female adult participants and are therefore also presented separately. Appendix C

(Tables C1 and C2) summarizes all adult and child questionnaire responses.

ATSDR used univariate and multivariate models to

evaluate the relationships between questionnaire data

and blood PFAS levels. This section summarizes

relationships that were found to be statistically

significant. For this EA, the following demographic and

exposure characteristics had an association with at

least one PFAS in either univariate or multivariate

models:

• age,

• sex,

• tap water consumption,

• drinking water source,

• use of a water filtration or treatment device,

• drinking water consumption rate,

• length of residence in the sampling frame,

• public water supply,

• kidney disease history,

• occupational exposure,

• consumption of selected local food items,

• cleaning frequency,

• breastfeeding (adult females and children), and

• childbirth (adult females).

Table 9 summarizes the demographic and exposure characteristics that were statistically significant in

each adult multivariate model.

ATSDR created mathematical models

to identify demographic and lifestyle

characteristics associated with PFAS

blood levels.

Univariate models evaluated the

effects of one variable, or exposure

characteristic, at a time while

multivariable models evaluated the

joint effect of multiple characteristics

on blood PFAS levels at the same time.

Multivariable regression models

describe the average increases in PFAS

blood levels for each unit increase in

the exposure characteristics.

Table 9. Summary of statistically significant variables (p<0.05) in multivariate regression

models

Parameter

PFHxS PFOS PFOA

All

Adult

Female

Adult

Male

All

Adult

Female

Adult

Male

All

Adult

Female

Adult

Male

Age (continuous)

      

—



Sex (categorical)



NA NA



NA NA — NA NA

Age × sex (continuous)*



NA NA — NA NA — NA NA

Years in sampling frame in the

past 20 years (continuous)

   

—

 

—



Kidney disease history

(categorical)



—



— — — — — —

Occupational Exposure

(categorical)



—



— — — — — —

Filter use (categorical)   —   —  — —

Consumption of fruits and

vegetables (categorical)

— — —



—



— — —

Home cleaning frequency

(categorical)

— — —   — — — —

 = statistically significant, ‘—’ = not statistically significant, NA = not applicable

* This variable is an interaction term between age and sex.

The following subsections briefly summarize results for these topics. All other results are presented in

Appendix C, as described below.

• Tables C1 and C2 present response

frequencies for all questions included in the

adult and child questionnaire, respectively.

These tables also present geometric means

and 95% confidence intervals around

geometric means stratified by the response

options (e.g., statistics are presented

separately for males and females) for PFHxS,

PFOS, PFOA, PFNA, PFDA, and MeFOSAA.

While blood levels of PFNA, PFDA, and

MeFOSAA were not found to be statistically

higher than the national geometric means,

both PFAS were detected at a high enough

frequency (greater than 60%) to present

meaningful results. Summary statistics are

therefore provided in Appendix C for

completeness, but not discussed below.

• Tables C3 and C4 present univariate

modeling results for all questions in the adult

and child questionnaire for the same six

PFAS, as data allow. Data are presented only

Goodness of Fit Measure

R-squared or R

is a statistical measure used

to evaluate how well a mathematical model

explains the measured data by looking at the

differences between the observed PFAS

concentrations and values predicted by the

model.

• An R

of 1 means the model completely

predicts the observed PFAS

concentrations, so that there are no

differences between the model and the

PFAS concentrations and 100% of the

PFAS concentrations are explained by the

model.

• An R

of less than 1 means that there are

measurements scattered higher and/or

lower than the model predictions and

there are differences

between the two.

when a category had at least 10 responses. Some categories were collapsed to meet this

threshold.

• Tables C5–C12 present multivariate modeling results for PFHxS, PFOS, and PFOA. Multivariate

models, including the goodness-of-fit measure, R-squared or R

, are presented separately for all

adults, male adults only, and female adults only. The closer the R

value is to 1, the more the

variables in the model explain the variability in blood PFAS levels. Across all models, R

values

ranged from 0.13 to 0.30. ATSDR modeled males and female adults separately to explore sex-

specific differences including the potential effect of childbirth and breastfeeding on female

blood PFAS levels. The variables considered in male-only and female-only models were limited

to those that were significant in final all-adult models. Final multivariate male-only models were

only significant for PFHxS and PFOA; the best model for PFOS was a univariate model consisting

of only a single significant variable. The final female-only models were only significant for PFHxS

and PFOS. ATSDR did not develop multivariate models for children because of the small sample

size for this population (n=28).

• Figures C1–C36 present box and whisker plots for unadjusted blood levels by each demographic

and exposure characteristic included in the statistical analyses.

Blood PFAS Levels and Age

Because many studies have found that older people have

higher blood PFAS levels, ATSDR investigated how Security-

Widefield EA participants’ ages related to their blood levels.

As Figure 4

illustrates, the blood levels for PFHxS, PFOS, and

PFOA increased with age in adults, but trends were

inconsistent in children.

For adults, ATSDR’s univariate analysis showed that blood

PFHxS, PFOS, and PFOA were higher in older individuals than

in younger individuals, and this finding was statistically

significant. As Figure 4 shows, PFHxS had the strongest age

dependence. The univariate analysis indicates that on

average, blood PFHxS levels in Security-Widefield EA

participants increased 2.5% for every year of participant age

in adults. This suggests a 28% increase in blood PFHxS levels

for every 10 years of participant age in adult participants.

The calculated age-related increases for PFOS (1.9% per year

of participant age) and PFOA (1.3% per year of participant

age) were lower.

ATSDR’s multivariate analysis provided further perspective on this trend, showing that the age

dependence was generally stronger for women than men among adults for PFHxS. For example, the all-

adult model for PFHxS (Appendix C, Table C5) suggests a 2.5% increase in blood PFHxS for every

additional year of participant age in female participants, and a 1.3% increase in blood PFHxS levels for

every additional year of participant age in males, when controlling for other characteristics; these

findings were statistically significant. Similar results were observed in the stratified male-only and

female-only models. Age also remained a significant predictor of blood levels for PFOS (1.7% per year)

and PFOA (1.0% per year) in all-adult multivariate models.

Variability describes the spread or

dispersion of data values. If the values

are similar to each other there is little

variability, if the values are spread out

there is more variability.

Multivariable regression can help us

understand how much of the

variability in PFAS blood levels can be

explained by the combination of

factors in the model such as age, sex,

and length of residency among others.

If the model does not explain a large

portion of the variability, that means

there are other unknown factors

influencing PFAS levels in blood.

Age was not statistically associated with blood PFAS levels in children under 18 in univariate analyses.

Note that multivariate models were not explored for children because of the small sample size.

Figure 4. PFAS blood levels in adults and children (log scale)

Blood PFAS Levels by Sex

ATSDR investigated how blood PFAS levels vary between males and females because previous research

has shown that, all other factors considered equal, adult males tend to have higher blood PFAS levels

than adult females. ATSDR’s univariate analyses showed that PFAS levels were higher in adult males

than in adult females for PFOS. Modeled blood levels in adult males were 43% higher for PFOS (

Figure

5). This estimate for PFOS was similar when controlling for other variables in multivariate models (42%).

When controlling for other variables, sex was also a significant predictor of blood PFHxS levels, and the

difference between males and females was larger in younger people. For example, 30-year-old males

had higher modeled blood PFHxS levels than 30-year-old females by 70%. For 50-year-old males, this

difference was reduced to 35% compared to 50-year-old females.

Blood levels of these three PFAS were not statistically associated with sex in children.

Figure 5. PFAS blood level in adults by sex (log scale)

Blood PFAS Levels and Tap Water Consumption

ATSDR investigated several questions from the adult and child questionnaires to characterize

relationships between blood PFAS levels and consumption of PFAS-contaminated drinking water. These

questions are about the drinking water source, amount of tap water consumed at home or school, and

residential history. In some cases, data trends may have been affected by subtleties in the wording of

exposure history questions, as described below. ATSDR also considered the effect of each participant’s

public drinking water system.

Drinking water source. For adults, ATSDR first considered participants’ primary drinking water source.

Adult participants were asked, “What is your current main source of drinking water in your home?” All

of the responses were tap water (68%) or bottled water (32%). In univariate analyses, adults who

primarily drank bottled water had significantly lower PFHxS (31%) blood levels when compared to adults

who primarily drank from a public water system. (Figure 6

). However, when controlling for other

variables in multivariate analyses, this association did not remain statistically significant. Note that the

exposure history question asked about current drinking water sources. It is possible that some

participants who reported currently drinking bottled water previously drank tap water when their

drinking water was contaminated.

Figure 6. PFAS blood level in adults by drinking water source (log scale)

Use of filtration device. ATSDR also considered relationships between blood PFAS levels and current use

of drinking water filtering and water treatment devices. As Figure 7 shows, 60% of participants reported

using a filter or treatment device on the tap water that they drink at home, 26% of participants reported

no filter or treatment device on the tap water that they drink at home, and 14% reported not drinking

tap water at all. In ATSDR’s univariate analyses, participants who reported not drinking tap water at all

had significantly lower PFHxS (52%), PFOS (43%), and PFOA (32%) blood levels when compared to those

who drank tap water with no treatment of filter device. When controlling for other variables in

multivariate analyses, not drinking tap water remained statistically significant in the all-adult

multivariate models with lower concentrations for PFHxS (36%), PFOS (32%), and PFOA (24%). This

association also remained statistically significant in the PFHxS and PFOS female-only multivariate

models.

Figure 7. PFAS blood level in adults by filter type (log scale)

Consumption rates. ATSDR also considered

participants’ self-reported tap water consumption

rates (Figure 8

). Adult participants were asked,

“During the time you lived in a home served by the

water source identified above [i.e., for the question

quoted three paragraphs ago], on average how many

8-ounce cups of water or beverages prepared with

tap water did you drink while at home per day?” In

univariate analyses, for every additional cup of tap

water an adult reported drinking at home per day,

blood PFHxS, PFOS, and PFOA increased by 3.7%,

2.0%, and 1.7%, respectively. However, these

associations did not remain significant in multivariate

analyses, which controlled for other potential

confounders.

As can be seen in Figure 8, 8% of participants

reported consumption rates that fall above the higher

end values (95th percentile) reported in EPA’s

Exposure Factors Handbook of 3,292 milliliters per

day (approximately 14 cups) [EPA 2019]. This

relatively small percentage of participants may have

overestimated their drinking water consumption, but

this is not expected to alter conclusions.

What are confounders?

Confounding is a distortion in the

estimated relationship between a

potential predictor and measure of

exposure due to the presence of a third

variable—called a confounder. In order for

confounding to occur, that third variable

must be associated with both the

predictor (or independent variable) and

the measure of exposure (or dependent

variable). For example, age can act as a

confounder on the estimated strength of

association between length of residence in

the sampling frame and blood PFAS levels.

By adjusting for these types of

confounding variables in multivariate

statistical models, ATSDR can calculate

less biased estimates of the relationships

between dependent and independent

variables of interest.

Figure 8. PFAS blood level in adults by tap water consumption rates (log scale)

Length of residency. For adults, ATSDR also considered the length of residency. The exposure history

questionnaire asked adults where they had lived for over the past 20 years. ATSDR calculated the total

amount of time participants reported living in the sampling frame over this period. These responses can

serve as a proxy for potential exposure to PFAS-contaminated drinking water in the community. That is,

the longer the residency within the sampling frame, the greater the likelihood of past PFAS exposure

from contaminated drinking water. Any resident reporting prior residences with addresses in Security,

Widefield, or Security-Widefield were assumed to fall within the sampling frame. Any addresses in

question (e.g., addresses in Colorado Springs or Fountain) were mapped and categorized as within or

outside of the sampling frame accordingly.

Figure 9

shows the relationship between reported residence duration in Security-Widefield for the past

20 years and blood PFAS levels. A consistent relationship was observed for PFHxS, PFOS, and PFOA:

blood levels statistically increased with the number of years participants lived in the sampling frame in

the past 20 years for PFHxS (9.8% per year), PFOS (4.1% per year), and PFOA (3.3% per year). The

multivariate analysis showed that all three PFAS continued to have a statistically significant relationship

with residency duration, and this effect was most pronounced for PFHxS. For every additional year that

an adult participant lived in Security-Widefield, blood PFHxS increased by 7.1%, while PFOS and PFOA

increased by 2.0%. This relationship continued to be significant for all PFAS in male-only models and for

PFHxS in female-only models.

Figure 9. PFAS blood levels in adults by length of residence in sampling frame (log scale)

Public Water Supply

ATSDR also consider participants’ public water supplies (Figure 10). Participants were asked which public

water supply that were served by. For participants who did not know which public water supply they

were served by, ATSDR mapped their addresses to identify the appropriate public water supply. In the

sampling frame, adult participants generally lived in homes that received drinking water from the

Security WD (n=203) or from Widefield WSD (n=109). One EA participant received water from Security

MHP. In univariate analyses, adult participants connected to Widefield WSD had blood PFOS levels 33%

greater than adult participants connected to Security WD. However, this association did not remain

significant in a multivariate model.

Figure 10. PFAS blood level in adults by public water supply (log scale)

Blood PFAS Levels and Kidney Disease

Adult participants were asked about whether they had a history of kidney disease, because it can affect

blood PFAS levels [Barry et al. 2013; Watkins 2013]. The questionnaire results indicated that only 6% of

adults (n=20) reported a diagnosis of kidney disease, but these adults did not have statistically different

blood PFAS levels than those without a diagnosis of kidney disease in univariate analyses. However, in

multivariate analyses, after controlling for other variables, participants who reported a history of kidney

disease had PFHxS blood levels that were 39% lower than those who did not. This variable was also

statistically significant in the male-only multivariate model. The results for kidney disease for this EA are

based on limited data and should be interpreted with caution. Note also that kidney disease was self-

reported and there may be misclassification with this variable.

Blood PFAS Levels and Occupational Exposures

Adult participants were asked about their occupational history over the past 20 years. Participants were

specifically asked about experience working at manufacturers of PFAS or PFAS-containing products (e.g.,

nonstick cookware, water-resistant clothing) and past work in firefighting, the military, or aviation.

Forty-one (13%) adult participants reported at least one occupational exposure in the past 20 years. All

41 participants reported working in either military, aviation, or firefighting. In univariate analyses,

participants with occupational exposures on average had lower blood PFHxS (33%) than adult

participants who reported no occupational exposures in the past 20 years (Figure 11

). In multivariate

models, participants with any occupational exposure continued to have significantly lower blood PFHxS

levels (28%). The direction of this association is the opposite of what was expected, but results are

based on a small number of participants and should be interpreted with caution.

Figure 11. PFAS blood level in adults by occupational history (log scale)

Blood PFAS Levels and Consumption of Selected Local Food Items

Some PFAS accumulate in plants, fish, and animals. The questionnaire asked adult and child EA

participants how often they consume locally grown fruits and vegetables, locally caught fish, and milk

from animals in the sampling frame. Too few adult EA participants reported consuming locally produced

milk (n=5) to allow for meaningful statistical analyses, and a statistically significant relationship was not

observed between consumption of locally caught fish and blood PFAS levels, though only 11 adults

reported consuming locally caught fish.

Blood PFAS levels were not associated with consumption of locally grown fruits and vegetables in

univariate analyses. However, in multivariate analyses, blood PFOS levels were higher by 52% among

adult EA participants who reported any consumption of locally grown fruits or vegetables (n=161)

compared to participants who reported no such consumption (n=154). Note that sex-specific models

showed that this relationship was primarily observed in males. While levels of PFOS were higher in

participants who consumed local produce, PFOS blood levels were not elevated in the community.

Blood PFAS Levels and Cleaning Fequency

Adult participants were asked about the frequency at which they clean their homes. In univariate

models, adult participants who reported cleaning their homes three times per week or more on average

did not have statistically different blood PFAS levels than adult participants who reported cleaning their

homes a few times per month or less. However, in all adult multivariate models, adult participants that

reported cleaning their homes three times per week or more on average had PFOS blood levels 24%

higher than adult participants that reported cleaning their homes a few times per month or less. Sex-

specific models showed that this relationship was primarily observed in females. While levels of PFOS

were higher in participants who cleaned their homes more frequently, the community’s average PFOS

blood level was not elevated.

Blood PFAS Levels and Past PFAS Blood Levels

Adult participants were asked if they previously had their blood tested for PFAS. Four EA participants

from three households submitted blood PFAS test results from the PFAS Assessment of Water and

Resident Exposure (PFAS-AWARE) health study, which tested PFAS levels in approximately 200 people in

El Paso County in 2018. Approximately 50 participants were retested in 2019 as part of the PFAS-AWARE

study. Information can be found online at https://pfas-aware.org

. Two additional participants from one

household submitted results from independent testing conducted in 2017.

ATSDR compared the change in PFAS blood levels between the first submitted test results for each

participant and the levels measured in this EA. Blood PFHxS and PFOS levels decreased in five of the six

participants between 8.0% and 13% per year and between 7.7% and 20% per year, respectively. In one

participant, PFHxS increased by 11% per year and in a different participant PFOS increased by 13% per

year. In all six participants, blood PFOA levels decreased by between 0.3% and 19% per year.

Blood PFAS Levels and Breastfeeding

During breastfeeding, some PFAS in the breast milk might be transferred from mother to child

Therefore, breastfeeding might reduce PFAS levels in mothers and increase PFAS levels in their

breastfed children [Kim 2020; Kingsley 2018]. Accordingly, the adult and child exposure history

questionnaires included questions about breastfeeding. A question was also included for children about

their consumption of formula (as opposed to breast milk), and if the formula was made using tap water.

Among adult female EA participants, 52% reported that they had breastfed a child, with an average

breastfeeding duration across all pregnancies of 17 months. In univariate and multivariate models for

adult females, neither having ever breastfed a child (yes/no) nor breastfeeding duration was associated

with PFAS serum levels.

Among child EA participants, ATSDR was unable to evaluate the association between having been

breastfed (yes/no) and blood PFAS levels because of the small sample. However, in univariate models

for children, the longer a child breastfed, the greater their blood levels of PFOS and PFOA. Each month

of reported breastfeeding was associated with an increase of 2.4% in blood PFOS and 2.2% in blood

PFOA. For example, 6 months of breastfeeding was associated with an infant’s modeled PFOS blood

level increasing from 2 µg/L to 2.3 µg/L.

Approximately one-third of the children in the Security-Widefield EA (36%) consumed infant formula

reconstituted with tap water (some of these children were also breastfed). In univariate models,

children that reported ever drinking formula reconstituted with tap water on average had blood PFHxS,

PFOS, and PFOA levels that were 57%, 44%, and 40% lower than children that reported never drinking

formula reconstituted with tap water. Similarly, each month of formula consumption was associated

with a decrease of 3% for blood PFOA.

Blood PFAS Levels and Childbirth (adult females and children)

The adult questionnaire asked female participants whether they had any biological children, and if so,

how many. Most adult female EA participants (84%) reported having biological children. Adult female

participants who reported having children on average had blood PFHxS levels that were 45% greater

than adult female participants who reported having no children. Similarly, each child was associated

with 17% increased PFHxS blood levels and 11% increased PFOS levels in univariate models. However,

these relationships were not significant in multivariate models.

Blood PFAS Levels and Other Variables

Through the exposure history questionnaires, ATSDR gathered information on several other possible

contributing factors to PFAS exposures. The variables listed below were not statistically associated with

blood levels of PFHxS, PFOA, and PFOS among EA study participants in univariate or multivariate

analyses. In some cases, ATSDR was not able to assess particular relationships because of small number

of participant responses.

• Race/Ethnicity. Adult and child participants were asked to provide information about their race

and ethnicity. However, because there were not enough participants in different race and

ethnicity categories to support robust statistical analyses, ATSDR focused on differences

between Security-Widefield EA participants who self-identified as White, non-Hispanic and

those who identified as non-White, or Hispanic. No statistical relationship was observed for self-

reported race/ethnicity and blood PFAS level in adults.

• Blood donation frequency. Adult participants were asked how often they donate blood or

plasma, because frequent blood and plasma donations might result in decreasing blood PFAS

levels. Relatively few participants (n=12) reported donating blood once or more a year, and no

statistically significant relationship was observed with blood PFAS levels in adults.

• Stain-resistant product use. Many stain-resistant products used to treat fabrics and carpet have

been formulated with PFAS. The exposure history questionnaire asked adult participants how

frequently they used these products; such uses may be associated with PFAS exposures.

Security-Widefield EA adult participants with any self-reported stain-resistant product use did

not have statistically elevated blood levels of any PFAS when compared to participants who

reported never using these products.

• Soil exposure. Adult and child participants were asked how often they play in or touch soil or

dirt in the sampling frame. No statistically significant relationship was observed for self-reported

soil contact frequency and blood PFAS levels in adults or children.

• Fast food consumption. PFAS may be present in fast food take-away containers and food

packaging. Consumption of fast food may serve as an additional source of PFAS exposure.

However, among Security-Widefield County EA adult participants, reported frequency of fast

food consumption was not statistically associated with blood PFAS levels. In recent years, fast

food packaging has likely been reformulated to contain shorter chain PFAS. This shift may make

it more challenging to link PFAS exposure to fast food consumption.

• Flooring. Adult participants were asked about the type of flooring in their living rooms, kitchens,

and bedrooms. While carpet has been linked to increased PFAS exposure because PFAS-

containing stain- and grease-repelling coatings are often applied to carpet [Beesoon et al. 2012],

the presence of carpet in EA participants’ rooms was not statistically associated with blood PFAS

levels among adults.

PFAS in Urine

The study protocol calls for ATSDR to initially analyze 10% of urine samples collected. The protocol

indicates that ATSDR will analyze all participants’ urine samples if the initial analysis shows geometric

mean urine concentrations of any PFAS higher than the NHANES 95

percentile values; however, this

threshold was not met. Note that only PFBA and PFHxA were detected in more than 5% of the NHANES

samples.

Information on urinary concentrations of PFAS in humans is limited, yet it may be important to

understand exposure to short-chain and alternative PFAS. Because urine is the primary route of

excretion for many PFAS, urinary concentrations may reflect more recent exposures than do serum

concentrations. Some PFAS were detected in serum but not in urine. These seemingly contradictory

results highlight the importance of using the appropriate biomonitoring matrix for EA. Concentrations of

biologically persistent compounds (like some PFAS) are expected to be higher in serum than in urine, as

was observed in this assessment. This trend is also evident in other biomonitoring studies in the general

population and in communities with known PFAS exposures [Calafat et al. 2019].

For the Security-Widefield EA, ATSDR randomly selected 36 participants’ urine samples for analysis.

These samples were provided by 34 adults and 2 children, and these individuals lived in 36 different

households. PFBA was the only PFAS detected in any of the 36 urine samples. Of note, the measurement

of trace levels of PFBA faces known challenges, including selectivity of the analytical instrumentation

and potential for external contamination [Abraham et al. 2021]. Therefore, we advise caution when

interpreting the PFBA results.

Table 10

presents PFBA summary statistics for the randomly selected urine samples and national

statistics for comparison. One of the 36 samples had PFBA urine concentrations higher than the NHANES

percentile. The protocol specified that all urine samples would be analyzed if the geometric mean

exceeded the 95

percentile from NHANES. Since no PFAS were detected in more than 60% of the

analyzed samples, no geometric means were calculated for any PFAS in urine and ATSDR did not analyze

the remainder of the urine samples.

Table 10. Community statistics for PFAS in urine reported in micrograms per liter

PFAS

Frequency of

Detection (%)

Range of

Concentrations

(µg/L)

Security-

Widefield

Geometric

Mean

(µg/L)

Security-

Widefield 95

Percentile

(µg/L)

NHANES

Geometric

Mean

(µg/L)

NHANES

Percentile

(µg/L)

PFBA 2.8 ND–0.4 NA* NA** NA* 0.300

µg/L = micrograms per liter, ND = not detected, NA – Not applicable

* Geometric mean was not calculated because chemical was not detected in at least 60% of the samples

(detected in 13.3% of samples in Calafat et al. [2019]).

** 95

percentile is below the limit of detection.

PFAS in Tap Water

As noted previously, ATSDR collected tap water samples from 18 randomly selected participant

households and analyzed these samples for PFAS. One household provided two filtered samples, two

households provided only an unfiltered sample, and 15 households provided both filtered and unfiltered

samples. Detection limits were 2 ppt for all PFAS, except for HFPO-DA (5 ppt).

PFAS were detected in three of the 17 filtered samples. In one of the filtered samples, PFBS, PFHxS,

PFHxA, PFOS, and PFOA were detected. In the second sample, PFHxA and PFHpA were detected and in

the third sample, only PFHxA was detected. The maximum concentrations in these filtered samples were

2.1 ppt PFBS, 3.5 ppt PFHxS, 51 ppt PFHxA, 2.3 ppt PFHpA, 11 ppt PFOS, and 3.0 ppt PFOA.

PFHxA was detected in seven of the 17 unfiltered samples. Four of those samples also had a detected

concentration of PFHpA, and one of those samples also had a detected concentration of PFOS. The

maximum concentrations in these unfiltered samples were 57 ppt PFHxA, 2.5 ppt PFHpA, and 3.0 ppt

PFOS.

Geometric means were not calculated for any PFAS in filtered or unfiltered tap water because 40% or

more of the results were non-detect. The detection limit, and measured concentrations were below

EPA’s HA of 70 ppt for PFOA and PFOS combined. There are no EPA health advisory levels for PFBS,

PFHxS, PFHxA, or PFHpA.

The reason that a larger number of PFAS were detected in filtered samples is unclear, as one might

assume that filtered water would be less contaminated than unfiltered water. A possible explanation is

related to filter maintenance, though this issue could not be fully explored as part of this assessment.

Because of the limited PFAS detections in the tap water samples, ATSDR did not investigate correlations

between these sampling results and the blood data.

PFAS in Household Dust

ATSDR collected dust samples from the same 18 randomly selected participant households where tap

water samples were collected and analyzed these samples for PFAS. These samples were taken from

multiple locations in each household, including the primary living space as identified by the homeowner

(e.g., living room, family room, television room), the kitchen, and the bedroom in which participants

reported spending the most time. When necessary, additional sampling was performed in other rooms

to allow ATSDR to collect the proper amount of dust for testing.

Table 11

lists the specific PFAS that were measured in dust along with detailed summary statistics (i.e.,

frequency of detection, geometric means, 95% confidence intervals around the geometric means, and

percentiles). Note that several PFAS were not detected in any sample and are therefore not included in

Table 11 (i.e., PFNS, N-EtFOSA, FtS 4:2, HFPO-DA, ADONA, 9CL-PF3ONS, and 11CL-PF3OUdS).

Table 11. Summary statistics for dust samples (n=18) collected in Security-Widefield

PFAS

FOD

(%)

Maximum

Detected

Result (ng/g)

Geometric

Mean

(ng/g)

95% Confidence

Interval for

Geometric Mean

(ng/g)

Percentiles (ng/g)

(Median)

PFBS 72 67.9 3.25 1.56–6.80 2.91 21.9 54.0

PFPeS 11 28.0 NA* NA* 1.05 2.90 5.64

PFHxS 72 267 3.53 1.82–6.86 2.82 9.05 42.2

PFHpS 11 3.25 NA* NA* 0.884 2.88 3.14

PFOS 100 96.0 12.2 7.20–20.7 10.9 48.8 81.5

PFDS 56 9.83 NA* NA* 1.35 5.00 7.63

PFDoS 28 16.3 NA* NA* 1.34 5.13 7.76

PFBA 67 160 11.0 5.76–20.9 7.88 53.2 141

PFPeA 56 10.6 NA* NA* 2.69 6.36 7.12

PFHxA 100 34.2 6.54 4.07–10.5 6.16 24.1 26.4

PFHpA 78 22.2 3.51 1.91–6.44 2.33 16.5 21.7

PFOA 89 65.1 7.99 4.47–14.3 6.52 34.7 39.5

PFNA 94 36.8 6.70 4.04–11.1 5.74 22.9 33.7

PFDA 89 13.4 3.92 2.57–5.97 3.48 11.5 11.8

PFUnA 44 12.2 NA* NA* 1.35 7.79 10.6

PFDoA 56 10.9 NA* NA* 1.88 6.83 8.20

PFAS

FOD

(%)

Maximum

Detected

Result (ng/g)

Geometric

Mean

(ng/g)

95% Confidence

Interval for

Geometric Mean

(ng/g)

Percentiles (ng/g)

(Median)

PFTrA 44 5.10 NA* NA* 1.35 3.19 3.57

PFTA 39 8.31 NA* NA* 1.35 3.14 3.69

PFOSA 17 3.13 NA* NA* 1.29 2.45 2.85

N-MeFOSA 6 5.20 NA* NA* 1.20 3.32 3.77

MeFOSAA 61 38.7 2.35 1.33–4.16 1.98 9.66 24.4

N-MeFOSE 61 1,440 26.8 14.0–51.2 19.0 96.1 383

EtFOSAA 72 12.9 3.08 1.92–4.96 2.82 11.1 12.4

N-EtFOSE 17 150 NA* NA* 7.85 21.6 36.1

FtS 6:2 44 54.7 NA* NA* 4.88 42.5 48.5

FtS 8:2 6 12.6 NA* NA* 4.19 9.79 11.4

FOD = frequency of detection, ng/g = nanograms per gram, NA = not applicable

A total of 18 dust samples are summarized in this table.

* Per the EA protocol, geometric means were not calculated for PFAS detected in less than 60% of samples.

Multiple PFAS (PFHxS, PFOS, PFOA, PFBA, PFNA, PFHxA, PFDA, PFHpA, PFBS, EtFOSAA, N-MeFOSE, and

MeFOSAA) were detected in greater than 60% of samples. N-MeFOSE and PFOS were detected with the

highest average concentration. N-MeFOSE and PFOS had geometric mean values of 26.8

nanograms/gram (ng/g)

(95% confidence interval = 14.0–51.2 ng/g) and 12.2 ng/g (95% confidence

interval = 7.2–20.7 ng/g). PFHxS and PFOA had geometric mean values of 3.5 nanograms/gram (ng/g)

(95% confidence interval = 1.8–6.9 ng/g) and 8.0 ng/g (95% confidence interval = 4.5–14.3 ng/g),

respectively.

To provide some context to the results summarized above, average levels of PFAS measured in the 18

samples collected as part of this EA were compared to average dust levels reported in other U.S.-based

studies (in communities with or without PFAS contamination). This includes evaluations of indoor dust

collected at 30 homes in the greater Boston area [Fraser et al. 2013], 124 homes in California [Wu 2015],

15 U.S. homes [Karásková et al. 2016], and 19 homes in Minnesota cities with PFAS-contaminated soil

and drinking water [Scher et al. 2018]. Across these studies, PFOA and PFOS were consistently reported

at the highest concentrations. Geometric mean concentrations ranged from 24 to 45 ng/g for PFOA and

27 to 35 ng/g for PFOS [Fraser et al. 2013; Wu et al. 2015]. Two of the studies did not report geometric

means; for these studies, median concentrations were reported at 9 ng/g and 51 ng/g for PFOA and 14

ng/g and 67 ng/g for PFOS [Karásková et al. 2016 and Scher et al. 2018, respectively]. Geometric mean

and median concentrations for PFOA and PFOS measured in the 18 samples collected as part of this EA

were lower than what was reported from these four studies. Details on these studies and comparisons

with all other measured PFAS can be found in Appendix A, Table A1.

While these results suggest that PFOS and PFOA measured in the dust samples collected in Security-

Widefield were found at lower levels than reported elsewhere in the United States, note that the studies

referenced here do not necessarily provide representative comparisons and are provided only for

This unit (in this case, representing nanograms of PFAS measured per gram of dust collected) is equivalent to

parts per billion and micrograms per kilogram.

additional context. The sample collection methods and analytical methods were also not consistent

among these studies.

ATSDR also evaluated the correlation between PFAS measured in dust and blood. This analysis included

analytical data from 18 dust samples and from the 35 blood samples collected from participants residing

in the same homes. Using log-transformed data, ATSDR calculated Pearson correlation coefficients for

the PFAS measured in at least 60% of the dust and the same PFAS measured blood samples for this

assessment. Data were log-transformed because dust and blood concentrations were log-normally

distributed.

PFOA measured in dust was statistically correlated (r=0.46, p=0.0053) with PFOA measured in blood.

MeFOSAA measured in dust was statistically correlated (r=0.57, p=0.0004) with MeFOSAA measured in

blood. None of the other PFAS measured in dust were statistically correlated (p<0.05) with the same

PFAS measured in blood. Note that the sample size for dust measurements in Security-Widefield is

relatively small. ATSDR will further explore these findings, as well as correlations between different PFAS

measured in dust and blood (e.g., the correlation between PFOA in dust and PFOS in blood) in the report

analyzing data across all EA sites.

The dust results presented here are exploratory and should be interpreted with caution. They are based

on a limited set of samples, and in some cases those samples are based on a small sample mass. The

target sample mass for this study was 1 gram, but this target was not always met. Results based on less

than 1 gram of dust have higher detection limits, a possible source of bias.

Discussion

At least one PFAS was detected in the blood of all Security-Widefield EA participants (100%). Because of

the widespread use of PFAS, such high detection frequencies are common in the general U.S. population

[CDC 2019]. PFHxS, PFOS, PFOA, PFNA, PFDA, and MeFOSAA were the most frequently detected

compounds in Security-Widefield EA participants (detection frequencies above 67%).

Results from this EA were compared to the NHANES data from 2015–2016.

Age-adjusted geometric

mean blood levels of PFHxS and PFOA were statistically higher than these national geometric means (6.9

and 1.2 times, respectively), and age-adjusted blood concentrations of PFOS, PFNA, and PFDA were

similar to or lower than national geometric means. ATSDR was unable to compare blood levels of

MeFOSAA because this PFAS was detected in less than 60% of NHANES samples.

All PFAS measured in blood for this EA have been phased out of production in the United States.

Following this phase-out, national blood PFAS levels have been steadily declining since 2000 [CDC 2019].

Differences between geometric mean Security-Widefield EA blood levels, collected in 2020, and the

NHANES 2019-2020 geometric mean (not yet available) could be greater than the differences between

geometric mean Security-Widefield EA blood levels and the NHANES 2015-2016 geometric mean

presented here.

Newer NHANES data are now available, but this report (and all individual EA reports) compares EA results to

2015-2016 NHANES data to be consistent with individual results letters provided to participants. ATSDR will

consider including the newer data in the report analyzing data across all EA sites.

ATSDR compiled blood PFAS levels for the three most prevalent PFAS (PFHxS, PFOS, and PFOA) to

provide further context on the current (2020) Security-Widefield EA blood levels (Appendix A, Table A2):

• For PFHxS, Security-Widefield EA participants’ blood levels are higher than the national

geometric mean from 1999–2000 (2.1 ppt), the time NHANES first measured PFAS and the time

the highest PFAS levels were observed [CDC 2019]. EA participants blood PFHxS levels are also

higher than levels observed in other communities with contaminated drinking water [PA DOH

2019; ATSDR 2013; Frisbee et al. 2009; NH DHHS 2016; NYDOH 2019].

• For PFOS and PFOA, blood levels among Security-Widefield EA participants are within the range

of those observed in other communities with contaminated drinking water (Appendix A, Table

A2). The levels reported here are lower than the national geometric mean PFOS and PFOA levels

for 1999–2000 (30.4 ppt and 5.2 ppt, respectively) [CDC 2019].

Generalizability of Security-Widefield EA Community Statistics

The random sampling recruitment method used for this EA was designed to produce summary statistics

of blood PFAS levels that were generalizable to the sampling frame as a whole (i.e., Security-Widefield

households in the area shown in Figure 1). Although the population invited to participate was likely

representative of the sampling frame, the population that ultimately enrolled was older. Specifically,

adults aged 50 or older represented 64% of the EA population compared with 29% of the sampling

frame. The EA population and the sampling frame as a whole also statistically differed in the proportion

of people who identify as White and as more than one race. Given the 6.3% response rate, it is also

possible that other factors were present at different rates than the community as a whole.

Since age was associated with blood PFAS levels in univariate analyses, the summary statistics for blood

PFAS (Table 5) may be biased, or deviate from the true value, when generalizing to the entire sampling

frame. ATSDR believes that any bias caused by differences in ethnicity would be minimal because race

and ethnicity were not statistically significant in multivariate analyses for PFHxS, PFOS, and PFOA.

However, ATSDR was concerned about the potential bias caused by the older age of EA participants

since levels of PFAS are known to vary depending on people’s age. Therefore, ATSDR quantified the

magnitude of the bias introduced by age by calculating geometric means that were adjusted to the age

distribution of the sampling frame (

Table 6). This analysis showed that the unadjusted geometric means

for blood PFHxS, PFOS, and PFOA biased high by 20% to 35%. Therefore, the sampling frame age-

adjusted geometric means for PFAS are more representative of the average levels in the community.

Relationships Between Demographics and PFAS Blood Levels

When evaluating differences in demographic factors by PFAS levels, adult males had statistically higher

geometric mean blood levels for PFHxS and PFOS, based on results from the all-adult multivariate

models, but did not have statistically elevated differences for other PFAS. In other studies in

communities with contaminated drinking water and for the general U.S. population [e.g., ATSDR 2013;

NH DPHS 2016; CDC 2019], sex-based differences are likely due to additional excretion routes in females

including through menstrual fluid, breastfeeding, pregnancy, and renal clearance rate differences

[ATSDR 2021]. PFAS have been demonstrated to pass through the placental barrier and into the

developing fetus during gestation, and have been measured in maternal serum, cord blood, breast milk

[Cariou et al. 2015], placenta [Chen et al. 2017], fetal tissue [Mamsen et al. 2019], and neonates [Wang

et al. 2014]. These studies suggest gestation, birth, and breastfeeding as excretion pathways for mothers

and gestation and breastfeeding as potential exposure pathways for infants. In this EA, the effect of

gestation (as measured by the number of children a female reported having had) and the duration of

breastfeeding were not significant predictors of PFAS blood levels in adult females. However, in

univariate models of child participants, breastfeeding duration was associated with increased PFOS and

PFOA blood levels, formula consumption (yes/no) was associated with decreased PFHxS, PFOS, and

PFOA blood levels, and formula consumption duration was associated with decreased PFOA blood

levels.

Blood PFAS levels were statistically higher in older adults than younger adults, and the effect of age was

stronger in female participants than males for PFHxS. Blood PFAS levels were found to remain

unchanged with age among children (3–18 years). Differences in the associations between blood PFAS

levels and age in adults and children have been observed in other studies [ATSDR 2013; NH DPHS 2016;

CDC 2019]. Generally, increasing blood levels in adults are due to the long biological half-lives of PFAS

and diminishing excretion rates with increasing age. The half-life of a chemical is the amount of time it

takes for 50% of the substance to be eliminated from the body. Most studies estimate a half-life of

PFHxS between 4.7 and 8.5 years, although some have estimated half-lives as long as 35 years [ATSDR

2021]. Most half-life estimates for PFOS are between 3.3 and 7.4 years, with a maximum of 27 years

[ATSDR 2021]. For PFOA, most studies estimate the half-life between 2.1 and 3.9 years with a maximum

of 10.1 years [ATSDR 2021]. In the presence of continued exposures that exceed clearance rates, PFAS

will accumulate in the human body over time.

In this EA, blood PFAS levels were not associated with age in children under 18. Although this trend was

not statistically significant, in other studies PFAS blood levels and age have been associated with

multiple factors including early life exposures and growth dilution. Early-life exposures may have

occurred since PFAS can cross the placenta and are found in breast milk [ATSDR 2021]. In addition,

hand-to-mouth touching and spending more time closer to the floor with settled dust in toddlers is

much greater than in older children. As a child grows, these early-life exposure factors diminish.

Additionally, large increases in body size lower blood levels despite increasing or constant PFAS body

burdens. This process is known as growth dilution [Koponen et al. 2018].

Significance of Drinking Water Exposures

ATSDR conducted EAs to learn more about how exposure to PFAS-contaminated drinking water affects

blood PFAS levels. This relationship is complicated because EA participants were likely exposed to PFAS

not only in contaminated drinking water but also in various consumer products and food items

unrelated to the water. ATSDR considered the following lines of evidence to understand the potential

significance of the drinking water exposure pathway:

• The two PFAS (PFHxS and PFOA) with statistically elevated blood levels in comparison to

national levels were detected in Security-Widefield’s water supplies as early as 2013. We do not

know if contamination began earlier because no data are available before 2013. The maximum

concentrations observed in finished drinking water in any of the three affected water systems

were 590 ppt for PFHxS, 210 ppt for PFOS, and 90 ppt for PFOA. In 2016, all three water systems

mitigated the contamination; however, these PFAS have very long biological half-lives (on the

order of years). Therefore, even though drinking water PFAS exposures in the Security-Widefield

were significantly reduced in November 2016, past drinking water exposures were likely a

contributing factor to the EA participants’ elevated blood PFAS levels, observed 3 years and 10

months later. Furthermore, in this EA, PFHxS had the largest deviation from the national average

and showed the greatest association with reported drinking water consumption, which is what

would be expected given that PFHxS has the longest half-life of the three PFAS.

• PFHxS, PFOS, and PFOA were highly correlated in blood (r between 0.71 and 0.73), suggesting

similar or common background sources or exposure pathways. PFHxS and PFOS, and to a lesser

extent PFOA, have many common exposure sources, as these compounds are often found

together in consumer products. While correlations between PFAS have been observed in other

studies [NH DPHS 2016; ATSDR 2013; CDC 2019], the correlations observed between these three

PFAS in this EA are much higher than those observed in the general U.S. population (r between

0.46 and 0.66) [Calafat et al. 2007b]. Instead, the high correlation between PFHxS, PFOS, and

PFOA is consistent with those found in the blood of people living in communities with

contaminated drinking water [ATSDR 2013], providing further evidence that drinking water was

likely a contributing source of exposure among Security-Widefield EA participants. In addition,

the correlations between PFHxS, PFOS, and PFOA in this study are much higher than the

correlations observed for PFNA, PFDA, and MeFOSAA, three compounds that were detected in

Security-Widefield’s drinking water, providing further evidence of a distinct exposure pathway

for these three compounds.

• Univariate statistical analyses of the EA data found that one of the most consistent predictors of

adult blood PFAS levels was length of residency in Security-Widefield. ATSDR considered

residency duration to be a suitable surrogate for drinking water exposures because only

residents who lived in the sampling frame before November 2016 would have had any exposure

to the PFAS-contaminated drinking water, and because of the likelihood that exposure would

increase with the number of years that EA participants lived in the area. However, since older

adults tended to live in the sampling frame longer, this variable was correlated (r = 0.31) with

age in adults. Because of this, it was unclear from univariate models alone whether the

association between the time someone lived in the sampling frame and PFAS blood levels was

primarily due to age. After controlling for age, sex, and other data characteristics, the

multivariate statistical analysis found that residency duration remained statistically associated

with blood PFHxS, PFOS, and PFOA levels, and tap water consumption did not remain

statistically associated with blood PFAS levels. However, multivariate models conducted

separately for males and females suggest that these relationships were primarily observed in

male participants for PFOS and PFOA. Furthermore, multivariate regression models did not

explain a large portion of the variability in participants’ blood PFAS levels (R

ranged between

0.13 and 0.30 in the “all adult” models), indicating that many factors are not accounted for.

• ATSDR investigated several questions from the adult and child questionnaires to characterize

relationships between blood PFAS levels and consumption of PFAS-contaminated drinking

water. In ATSDR’s univariate analysis, increased tap water consumption at home was associated

with increased PFHxS, PFOS, and PFOA. However, these associations did not remain significant

in multivariate models. In ATSDR’s univariate and multivariate analyses, participants who

reported drinking only bottled water on average lower PFHxS, PFOS, and PFOA blood levels than

participants who reported drinking tap water with no filter or treatment device. Even though

drinking water consumption rates were not statistically associated with blood PFAS levels as

expected, the associations with bottled water consumption provided further evidence for a

drinking water exposure route.

• ATSDR also considered which public water system served EA participants. In ATSDR’s univariate

analyses, adult participants connected to Widefield WSD had blood PFOS levels greater than

adult participants connected to Security WD. However, this association did not remain

significant in a multivariate model.

Taken together, the data suggest that past drinking water exposure contributed to the elevated blood

levels of PFHxS and PFOA observed in the Security-Widefield EA participants.

Other Exposure Characteristics

Other exposure characteristics that showed significant associations with blood levels of one or more

PFAS in either univariate or multivariate analyses included the following:

• Kidney disease. Previous research shows that kidney disease can affect blood PFAS levels [Barry

et al. 2013; Watkins 2013]. Six percent of adults (n=20) reported a diagnosis of kidney disease,

but these adults did not have statistically different blood PFAS levels than those without a

diagnosis of kidney disease in univariate analyses. However, in multivariate analyses participants

who reported a history of kidney disease had PFHxS blood levels that were 39% lower than does

who did not. The results for kidney disease for this EA are based on limited, self-reported data

and should be interpreted with caution.

• Occupational Exposure. Workers can be exposed to PFAS through job tasks that involve

manufacturing or working with PFAS. In both univariate and multivariate models, adult

participants who reported at least one occupational exposure in the past 20 years on average

had lower blood PFHxS levels that those who reported no occupational exposure. Although this

result was the opposite of expected, it is based on a relatively small sample of participants with

occupational exposure (n=41).

• Local fruits and vegetables. In multivariate analyses, blood PFOS levels were higher among adult

EA participants who reported any consumption of locally grown fruits or vegetables compared

to participants who reported no such consumption.

• Cleaning frequency. In multivariate analyses, adult participants that reported cleaning their

homes three times per week or more on average had higher PFOS blood levels than adult

participants that reported cleaning their homes a few times per month or less.

While these two last exposure characteristics showed significant associations with PFOS, PFOS blood

levels were not elevated in the community. All of these observations are based on limited data and

should be interpreted with caution; they will be re-examined in the report analyzing results across all EA

sites.

Security-Widefield Community-Wide Findings

Finding 1. Average blood levels of PFHxS and PFOA in the Security-Widefield EA site

participants are higher than national levels. Averages of other PFAS were not higher than the

national levels or were detected too infrequently to compare to national levels.

Geometric means (i.e., averages) for PFHxS and PFOA blood levels were statistically higher (p<0.05) in

Security-Widefield EA participants when compared to CDC’s NHANES (2015–2016) testing, which was

limited to people over 12 years old. The statistically higher blood PFAS levels were observed for both

unadjusted geometric means for all EA participants and geometric means adjusted to the age

distribution of the U.S. population from NHANES 2015–2016.

Of the PFAS analyzed in blood, PFHxS had the largest elevations when compared to national levels. The

age-adjusted geometric mean blood PFHxS level among EA participants was 6.8 times the national level.

Blood PFHxS levels were above the national geometric mean for 96% of the Security-Widefield EA

participants and above the NHANES 95

percentile for 75% of the participants. The age-adjusted

geometric mean blood PFOA level was 1.2 times the national level.

Other PFAS measured in this EA (PFOS, PFNA, PFDA) were not higher than national levels. ATSDR was

unable to compare the geometric mean MeFOSAA levels because MeFOSAA was detected in less than

60% of NHANES samples. PFUnA was detected in fewer than 60% of the EA participant samples; due to

the large percentage of samples below the limit of detection, geometric means were not calculated.

Finding 2. Elevated blood levels of PFHxS and PFOA may be associated with past drinking

water contamination.

PFHxS, PFOS, and PFOA were detected in Security-Widefield water systems as early as 2013, though

contamination likely began earlier. Two of these PFAS (PFHxS and PFOA) had statistically elevated blood

levels compared to national geometric means. The maximum concentrations observed in finished water