New Castle County (DE) near New Castle Air National Guard Base

New Castle

PFAS Exposure Assessment Community Level Results

In 2019, the Centers for Disease Control and Prevention (CDC) and the Agency for Toxic Substances and Disease Registry (ATSDR) started exposure assessments (EAs) in communities near current or former military bases known to have had per- and polyfluoroalkyl substances (PFAS) in their drinking water. Individuals who participated in the EAs provided blood and urine samples to CDC/ATSDR for analysis. We sent letters to participants that included their individual lab results. An example letter of the test results letter and the community level results are available here. We also sent local health care providers exposure assessment information and clinician guidance on PFAS pdf icon[PDF – 471 KB].


The New Castle Air National Guard Base used aqueous film forming foam containing PFAS for firefighting training in the past. Groundwater sources used for drinking water in areas east and southeast of the base were contaminated with PFAS. Residents who may have been affected include those who live in and near the City of New Castle. 

In 2014, two drinking water systems serving the New Castle area, Artesian Water and Municipal Services Commission (MSC) of the City of New Castle, were found to contain PFAS levels exceeding the Environmental Protection Agency’s (EPA) health advisory. 

After receiving the PFAS test results, both water systems upgraded their systems to reduce PFAS exposures, including installation of granular activated carbon (GAC) filtration systems. In 2017, the Delaware Department of Natural Resources and Environmental Control reported that the GAC filtration systems had reduced levels of two specific PFAS, PFOS and PFOA, below the EPA health advisory. 

Some PFAS stay in people’s bodies for a long time so we will still be able to measure them even if the exposures stopped years ago. 

Participating in an exposure assessment helps individual participants and their community better understand the extent of environmental exposures to PFAS. A random selection of households impacted by PFAS in their drinking water were identified. Selected households received a letter in the mail from CDC/ATSDR explaining the exposure assessment and registration process. They also received a phone call from a representative to answer questions and register them for the exposure assessment. Household members were eligible if they were 3 years of age or older, did not have a bleeding disorder and were not anemic, and they had lived in the sampling area for one year prior to August 5, 2014 (for MS customers), or July 18, 2016 (for Artesian customers).  Inclusion of children in the exposure assessment was dependent on parent or legal guardian consent.

Sampling Area

The sampling frame for the New Castle exposure assessment includes customers of the Artesianexternal icon and Municipal Services Commission (MSC)external icon water supply systems.  Identification and mitigation of PFAS in these water systems occurred in separate but parallel paths as outlined in the figure below. The eligibility dates reflect the timeline of past exposures to PFAS via drinking water.

Selected households were eligible to participate if they resided in the sampling area for one year prior to the following eligibility dates:

The map shows the sampling area where the exposure assessment will occur. It focuses on an area where residential tap water PFOA and/or PFOS concentrations were above federal or state guidelines. The boundary of this area represents all customers of the Municipal Services Commission water system and all Artesia customers who live in the vicinity of three water treatment facilities (Jefferson Farms, Wilmington Manor 1, and Wilmington Manor 3.


CDC/ATSDR began an exposure assessment in New Castle in late summer 2019. Recruitment of participants took approximately 6 weeks. After that, CDC/ATSDR was in New Castle County from October 16 through October 26, 2019 to test participants. 

CDC/ATSDR completed the analysis of environmental and biological samples. Individual test results were mailed to participants on May 22, 2020. If you participated in the exposure assessment and have not received your individual test results, please contact ATSDR at CDC and ATSDR will write a final report summarizing the findings and recommendations for the community and present the results at a public meeting.

Timeline of Exposure Assessments for New Castle County. The information session, recruitment, and field work/sample collection phases have been completed. Currently analyzing samples. Next steps mailing individual test results and community meeting.

Information Session

For information on work being done in New Castle, DE, contact Karl Markiewicz PhD., Senior Toxicologist/Regional Liaison, 215-814-3149,

Page last reviewed: December 7, 2020