Berkeley County (WV) near Shepherd Field Air National Guard Base

Berkeley County


In 2019, the Centers for Disease Control and Prevention (CDC) and the Agency for Toxic Substances and Disease Registry (ATSDR) conducted an exposure assessment (EA) in and around the City of Martinsburg in Berkeley County, West Virginia, near Shepherd Field Air National Guard Base. CDC/ATSDR sent the individual test results to participants and released summary results to the community in May 2020. The PFAS exposure assessment report [PDF – 3 MB] was released in January 2022.

Why did we select the Berkeley County EA site?

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. The Berkeley County EA site was one of several sites nationwide identified with PFAS drinking water contamination from use of products such as aqueous film forming foam (AFFF).

The Shepherd Field Air National Guard Base previously used AFFF containing PFAS for its firefighter training, possibly as early as the 1970s. Over time, the PFAS from the AFFF entered the ground, moved into the groundwater to offsite locations, and affected the City of Martinsburg’s Big Springs well located downgradient of the Base. This well supplies water to customers from both the City of Martinsburg and the Berkeley County Public Service Water District (PSWD).

In May 2016, the City of Martinsburg removed its Big Springs well from service. They installed a treatment system and brought the Big Springs well back online in December 2017.The City of Martinsburg now conducts routine monitoring to ensure treatment is effectively removing PFAS.

Based on the information ATSDR has reviewed, the City of Martinsburg and the Berkeley County PSWD public drinking water supplies currently meet the U.S. Environmental Protection Agency’s (EPA) 2016 health advisory (HA) for PFAS in drinking water. At this time, ATSDR does not recommend community members who get their water from the City of Martinsburg or Berkeley County PSWD use alternative sources of water.

Sampling Area and Eligibility

Sampling Frame for Berkeley County Site


Timeline of Exposure Assessments Berkeley

How was the testing conducted?

ATSDR invited all Berkeley County residents living near Shepherd Field Air National Guard Base who met eligibility criteria to participate in the EA. Household residents must have

  1. lived within the sampling area and received their drinking water from by the City of Martinsburg or the Berkeley County PSWD) for at least 1 year before May 19, 2016, (these residents have the greatest likelihood of past exposures to PFAS via the public drinking water supplies),
  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.

Households with private wells were not eligible for participation. Measuring PFAS in the blood of people from selected households allows us to estimate exposure from consumption of public drinking water for the entire community in the affected area, even those who were not tested.


In May 2020, CDC/ATSDR released a summary [PDF – 356 KB] of the biological and environmental test results. The full report was released January 20, 2022 and a summary of the report’s findings is presented below. The full report is available here.

In September and October 2019, ATSDR collected samples and other information from participants.

analyzed data from


people, including children



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Everyone completed a questionnaire, and most people provided blood and urine samples.

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The serum portion of the blood was analyzed for PFAS.

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ATSDR collected samples of tap water and dust from some homes.

ATSDR sent each participant their individual results in May 2020.

Key Takeaways

  • Levels of PFHxS in the blood of Berkeley County EA participants were 2.5 times higher than national levels.
    Other PFAS measured in blood (PFOS, PFOA, PFNA, and PFDA) were similar to or detected too infrequently
    to compare to national averages.
  • Elevated blood levels of PFHxS may be linked with past drinking water contamination.
  • Some demographic and lifestyle characteristics were linked with higher PFAS blood levels.
  • All tap water samples collected during the EA in 2019 met the EPA’s health advisory for PFAS in drinking water.
What did we learn about PFAS levels in blood?

The average blood level of one PFAS (PFHxS) in the Berkeley County EA site participants was higher than the national average.

Of the seven PFAS tested at the Berkeley County EA site, five PFAS were detected in more than 74% of the blood samples collected: PFHxS, PFOS, PFOA, PFNA, and PFDA.

Since 1999, the National Health and Nutrition Examination Survey (NHANES) has measured PFAS levels in blood in the U.S. population. PFAS levels are shown to be age dependent and tend to increase with age in part due to longer periods of exposure. ATSDR adjusted blood levels of EA participants at the Berkeley County EA site for age to enable meaningful comparison to the NHANES dataset. After adjusting for the effects of age, PFHxS remained elevated compared to levels nationwide*. Age-adjusted averages are more representative of the Berkeley County EA site community.

Berkeley County blood level graph

*ATSDR initially reported PFOS levels were above national average; after statistical analysis this difference was not observed.


Elevated blood levels of PFHxS at the Berkeley County EA site may be linked with past contamination of the public drinking water systems.

PFHxS was first detected in the City of Martinsburg’s Big Springs well in 2014. It is likely that contamination began earlier, but no data are available before 2014. This contaminated well also supplied water to the Berkeley County PWSD. By December 2017, the City of Martinsburg and Berkeley County PWSD drinking water met the EPA’s HA for PFOA and PFOS. There were over 3 years and 5 months between the reduction of exposure via contaminated drinking water and the collection of the EA blood samples. Because of the long half-lives of PFAS in the human body, past drinking water exposures may have contributed to the EA participants’ blood levels. Typically, participants who had greater blood PFHxS levels also had greater blood PFOS and blood PFOA levels. This correlation suggests a common exposure source, such as the City of Martinsburg or Berkeley County PSWD public water supply, though other sources of exposure may also have contributed to the observed blood levels.

Participants who lived in the City of Martinsburg service area had 60% higher PFHxS blood levels than those who lived in the Berkeley County PSWD service area.

Both water systems used contaminated water from the Big Springs well. It was mixed with uncontaminated water from other parts of the system. It is possible that more uncontaminated water was mixed into the Berkeley County PSWD. ATSDR used statistical models to study relationships between various demographic and lifestyle characteristics of the tested residents. The models showed that, in general

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Blood levels of PFHxS, PFOS, and PFOA varied by age.

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In females, blood levels increase by 1.5% to 2.4% for every year of age.

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In males, blood levels of PFHxS decreased by 0.5% but increased for PFOS and PFOA by 0.2% for every year of age.

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Males had higher blood levels of PFHxS, PFOS, and PFOA than females.

The difference between males and females was larger in younger people.

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Long-time residents have higher PFHxS blood levels.

PFHxS increased by 5.3% for every additional year an adult participant lived in Berkeley County EA site.

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Participants who reported
donating blood at least once a year had 31% lower blood levels of PFOS than participants who never reported donating blood.

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Participants with a reported
history of kidney disease had PFOS blood levels that were 27% lower than those who did not.

Virtual Information Session

CDC and ATSDR invite all residents in and around they City of Martinsburg to attend a virtual information session to learn more about the results of the PFAS exposure assessment. Experts will answer community questions.

February 3, 2022
6:00-7:30 PM ET
To register, go to:

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