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Results of PFAS exposure study show New Castle residents' blood levels above national average

Sophia Schmidt
Delaware Public Media

New Castle-area residents exposed to a toxic group of chemicals are learning how much remains in their bodies.

Residents around the New Castle Air National Guard base were exposed to public drinking water contaminated with chemicals used in firefighting foam on the base.

Now some are finding out how much of these long-lasting chemicals — known as PFAS— they have in their blood, as part of a study of eight similarly exposed communities across the country the U.S. Centers for Disease Control and Prevention (CDC) started last year. 

Some studies in humans with PFAS exposure have shown the chemicals may interfere with the body’s natural hormones, increase cholesterol levels, affect the immune system and increase the risk of some cancers, according to the CDC. The chemicals, which are used in consumer products from food wrappers to carpets, are ubiquitous but not well understood.

The blood of New Castle residents who participated in the study contains three specific PFAS chemicals at levels several times the national average, according to aggregate results released Thursday. Blood levels of three other PFAS chemicals were found to be similar to national averages. 

The study found the average concentration of the chemical PFHxS in the participants’ blood to be almost 17 times the national average established in a 2015/2016 National Health and Nutrition Examination Survey. The participants’ average blood level of PFOS was more than four times the national average, while their blood level of PFOA was just over three times the national average. 

The more than two hundred New Castle participants are receiving their individual results, including how they compare to others who were tested, by mail. A sample letter from the U.S. Department of Health and Human Services states that scientists do not know what the levels mean for participants' health.

“The likelihood of adverse health effects depends on several factors, such as the concentration of PFAS, as well as the frequency and duration of exposure,” the letter reads. “More frequent exposure can increase risk. Higher concentration and length of time exposed can lead to increased risk. Your participation in this study, when combined with others, may eventually help us better understand any potential health risks from PFAS exposure in the future.”

State Sen. Stephanie Hansen (D-Middletown) says the state should look into funding testing for other Delawareans who may have been exposed to the chemicals—like in Dover or Blades

“Now that we know there is a higher level in the residents in New Castle, in an area where we believe a release has happened, I think it would be good to test residents in other areas where we believe a release has happened as well,” she said. “This would seem to say that they’re likely to have been impacted. So we need to know whether that’s the case.”

Hansen is among several lawmakers pushing for a state limit on some PFAS chemicals in public drinking water. The federal government has only set an unenforceable health advisory level for the chemicals.

“If you have water that’s contaminated above a health advisory level like that, there isn’t the ability to require it to be cleaned up,” she said. 

A bill introduced to the state House last week would require state health and environmental regulators to study the chemicals and set an enforceable maximum contaminant level. 

Results of the New Castle PFAS exposure assessment were delayed for months because of the CDC’s response to the coronavirus. 

CDC officials say public drinking water around New Castle currently meets federal standards—and do not recommend area residents seek alternative sources of water.


Sophia Schmidt is a Delaware native. She comes to Delaware Public Media from NPR’s Weekend Edition in Washington, DC, where she produced arts, politics, science and culture interviews. She previously wrote about education and environment for The Berkshire Eagle in Pittsfield, MA. She graduated from Williams College, where she studied environmental policy and biology, and covered environmental events and local renewable energy for the college paper.
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