PFAS Exposure Assessment: New Castle County, Delaware

Background

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 New Castle, located in New Castle County, Delaware, near New Castle 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 was released in February 2022.

Why the New Castle County site was selected

When selecting EA sites, ATSDR considered the extent of PFOA and PFOS contamination in drinking water supplies. It also considered the:

• Duration that exposure may have occurred.
• Number of potentially affected residents.

The New Castle County EA site was identified with PFAS drinking water contamination from use of products such as aqueous film forming foam (AFFF).

The New Castle Air National Guard Base (The Base) used AFFF containing PFAS for its firefighter training in the past. Over time, the PFAS from the AFFF entered the ground and moved into the groundwater to offsite locations. This affected nearby municipal wells.

In 2014, two drinking water systems serving the New Castle area were found to contain PFAS levels exceeding the Environmental Protection Agency's (EPA) provisional health advisory (HA):

• Artesian Water
• Municipal Services Commission (MSC) of the City of New Castle

In 2016, one additional well in Artesian's system was found to exceed the (lower) 2016 EPA HA. Both water systems removed contaminated wells from service and upgraded their systems to reduce PFAS exposures.

With a goal to reduce PFAS concentrations below the EPA HA, Artesian also:

• Mitigated PFAS exposures below the provisional HA in 2014.
• Took additional action to remove that well from service.

Final mitigation was achieved by MSC in August 2014 and by Artesian in July 2016.

Based on the information ATSDR has reviewed, the Artesian and MSC public drinking water supplies currently meet or are below the EPA's 2016 HA for PFAS in drinking water.

Sampling area

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Timeline

How testing was conducted

ATSDR randomly selected households to participate in the PFAS exposure assessment. To be eligible, household residents must have:

• Used either
  • The MSC drinking water system for at least 1 year before August 5, 2014.
  • Or the Artesian Water system at least 1 year before July 18, 2016.
• Been older than three years at the time of sample collection.
• Not been anemic or had a bleeding disorder that would prevent giving a blood sample.

Measuring PFAS in the blood of people from randomly 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.

Results

In May 2020, CDC/ATSDR released a summary of the biological and environmental test results. The full report was released February 2, 2022. A summary of the report's findings is below.

In October 2019, ATSDR collected samples and other information from participants. ATSDR collected and analyzed data from the following:

• 214 people
  • 203 adults
  • 11 children
• 134 households
• Questionnaires completed by all participants
• Blood and urine samples provided by most participants
• The serum portion of the blood from blood samples
• Samples of tap water and dust from some homes

ATSDR sent individual results to each participant in November 2020.

Other testing

Only one PFAS (PFBA) was detected in urine and at low concentrations.

All tap water samples collected during the EA in 2019 met the EPA's HA for PFAS in drinking water.

PFAS contamination in house dust was similar to that reported in other studies (with and without PFAS contamination). This likely contributed to PFAS levels in the blood.

Key takeaways

Levels of some PFAS in blood (detailed below) in New Castle County EA site were as much as 9.8 times higher than national levels. Other PFAS measured in blood (PFUnA and MeFOSAA) were detected at low concentrations but could not be compared to national levels.

• Elevated blood levels 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 PFAS in drinking water.

What these results mean

Of the seven PFAS tested at the New Castle County EA site, at least one PFAS was detected in all participants. All seven PFAS were detected in more than 60% of the blood samples collected:

• PFHxS
• PFOS
• PFOA
• PFNA
• PFDA
• PFUnA
• MeFOSAA

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. In its analysis, ATSDR adjusted blood levels of EA participants at the New Castle County EA site for age to enable meaningful comparison to the NHANES dataset. After adjusting for the effects of age, PFHxS, PFOA, PFOS, PFNA and PFDA were all elevated compared to national levels. Age-adjusted averages are more representative of the New Castle County EA site community.

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* ATSDR initially reported average blood levels of three PFAS (PFHxS, PFOA, and PFOS) above national averages after statistical analysis levels of five PFAS (PFHXs, PFOS, PFOA, PFNA, and PFDA) were found to be higher.

Future direction

What was learned about PFAS levels in blood

Of the seven PFAS tested at the New Castle County EA site, at least one PFAS was detected in all participants. All seven PFAS were detected in more than 60% of the blood samples collected:

• PFHxS
• PFOS
• PFOA
• PFNA
• PFDA
• PFUnA
• MeFOSAA

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.

ATSDR adjusted blood levels of EA participants at the New Castle County EA site for age to enable meaningful comparison to the NHANES dataset. After adjusting for the effects of age, PFHxS, PFOA, PFOS, PFNA and PFDA were all elevated compared to levels nationwide. Age-adjusted averages are more representative the New Castle County EA site community.

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Information to protect our communities

Three PFAS (PFHxS, PFOS, PFOA) were detected in the MSC system in 2009. In 2014, they were found in the Artesian Water system. We do not know if PFAS contamination began. This is because data are not available before 2009 for the MSC system and before 2014 for the Artesian Water system.

In 2014, the MSC water supply system mitigated the contamination. The Artesian water supply system took similar action in 2014. In 2016, an additional well was found to be contaminated above the 2016 EPA HA so final mitigation in the Artesian system was not completed until 2016.

PFAS have long half-lives in the human body. Drinking water exposures were reduced 3 to 5 years before the collection of EA blood samples. Therefore, past drinking water exposures were a likely contributing factor to the EA participants' elevated blood PFAS levels.

Generally, participants with elevated PFHxS blood levels also had elevated PFOS and PFOA blood levels. This suggests a common source of exposure, such as the drinking water supply. Other sources of exposure were not measured but could have contributed to blood PFAS concentrations of the EA participants.

Additional observations

Adults living in the MSC service area had higher PFAS blood levels than those in the Artesian Water service area. The differences in participants' PFAS blood levels between the two water systems were consistent with the historical levels of PFAS in the drinking water, for example, higher historical PFAS levels in MSC public water.

Long-time residents have higher PFHxS, PFOS, and PFOA blood levels (for either MSC or Artesian users).

Adults using at least one water filter or treatment device had lower PFHxS, PFOS, and PFOA blood levels compared to those who did not for either water system.

Statistical findings

ATSDR used statistical models to study relationships between various demographic and lifestyle characteristics of the tested residents. The models showed that, in general:

Males had 28% higher blood levels of PFOS than females.

Adults reporting a history of kidney disease had 56% higher PFHxS blood levels than those who did not report kidney disease.

Adults reporting cleaning their homes an average of 3+ times per week had 42% lower PFHxS and 34% lower PFOS blood levels than adults who reported cleaning a few times per month or less.

Exposure in children

Most associations in children under 18 years could not be evaluated due to the small number of child participants (n=11). That said, blood levels of PFHxS and PFOS increased with self-reported water consumption levels at school. This finding should be interpreted with caution due to the small number of children who participated in this EA. The final report on all EA sites will include a more robust analysis of children.

Additional testing

Only one PFAS (PFBA) was detected in urine and was detected at low concentrations.

All tap water samples collected during the EA in 2019 met the EPA's HA for PFAS in drinking water.

PFAS contamination in house dust was similar to that reported in other studies (with and without PFAS contamination). This likely contributed to PFAS levels in the blood.

What the results mean for the community

This PFAS EA provides evidence that past exposures to PFAS in drinking water have impacted the levels of some PFAS in people's bodies. PFAS are released from the body over a long period of time. This allowed ATSDR to measure PFAS even though exposures through drinking water were lowered years ago.

Not everyone exposed to PFAS through drinking water in New Castle had the opportunity to participate. By including a random selection of households, the results help estimate exposure for all community members, including those who were not tested. This means that average PFAS levels reported in this assessment may be representative of levels among community members living in the sampling frame who meet the eligibility criteria.

PFAS found in 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 exposure contribution from PFAS in drinking water at the New Castle County EA site has been mitigated. There are still actions community members and city officials can take to further reduce exposures and protect public health.

What else

Community members

For information on water quality, read Consumer Confidence Reports for Artesian Water and/or MSC.

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.

Eliminate or decrease potential exposure to PFAS when possible. This pertains to goods like stain-resistant products and food packaging. Refer to Questions and Answers on PFAS in Food for more information.

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.

Follow the advice of your health care provider. This includes recommendations for checkups, vaccinations, prenatal care, and health screening tests.

ATSDR does not recommend retesting for PFAS in EA participants. At this time, ATSDR does not have plans to conduct additional blood testing for PFAS.

The biological half-lives of many of the PFAS measured in people's blood are long. PFHxS, in particular, has one of the longest half-lives. Some estimates range in the decades. This means that PFAS blood levels are not expected to change significantly in the near-term. This is even if exposure stops. It is also unclear what an individual's PFAS test results mean in terms of possible health effects.

Pay attention to advisories about food consumption, like local fish advisories.

Follow the advice of your child's health care provider and the recommendations for well child checkups, vaccinations, and health screening tests. Refer to information to help identify those vaccinations and tests.

For more information on 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.

Artesian Water and MSC

Steps can be taken to ensure concentrations of PFAS remain below the EPA's HA. For the community drinking water near the New Castle County EA site, both public water systems should:

• Continue to monitor concentrations of PFAS.
• Properly maintain all treatment systems to remove PFAS.

Results of PFAS drinking water monitoring should continue to be shared with the community through Consumer Confidence Reports for Artesian Water and/or MSC.

(Consumer Confidence Reports for Artesian Water, http://www.artesianwater.com/customer-service-center/artesian-water-quality-reports; Consumer Confidence Reports for MSC, https://newcastlemsc.delaware.gov/consumer-confidence-reports/).

Resources

• PFAS Exposure Assessment, New Castle County, DE: Fact Sheet
• PFAS Exposure Assessment, New Castle County, DE: Community-Level Summary Results Fact Sheet
• PFAS Exposure Assessment, New Castle County, DE: Report
• PFAS Exposure Assessment, New Castle County, DE: Report Appendix
• PFAS Exposure Assessment, New Castle County, DE: Report Consumer Summary