A U.S. Geological Survey report took aim at untreated well water in Delaware when it found widely distributed per-and polyfluorinated alkyl substances (PFAS) contamination statewide.
The USGS report released in December 2021 found a variety of types of PFAS in water from 16 of the 30 wells sampled in Delaware; one sample contained eight different types. Those that contained PFAS generally had low concentrations.
According to USGS data, all wells sampled receive groundwater from the Columbia aquifer, which supplies water for more than 90% of the state.
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“Even though use of some PFAS have been banned, we found that the chemicals are still present in the environment,” said Betzaida Reyes, USGS scientist and the author of the new study. “The Columbia aquifer is an important drinking water source for hundreds of thousands of people, and our research will help decision-makers and communities understand how PFAS are impacting the quality of some area groundwater.”
PFAS are a group of more than 4,000 manmade chemicals. The Environmental Protection Agency research indicates high concentrations of some PFAS may lead to adverse health outcomes in people.
The wells sampled in Delaware with the highest number of types of PFAS detected were in New Castle and Sussex counties, with five to eight compounds found in each well.
Two wells, one in each county, had concentrations of two types of PFAS, perfluorooctanoic acid, known as PFOA, and perfluorooctane sulfonate, known as PFOS, above the Environmental Protection Agency’s advisory level for lifetime consumption.
The four most frequently detected PFAS in this study were PFOA; perfluorohexanoic acid, known as PFHxA; PFOS; and perfluorohexane sulfonate, known as PFHxS.
“This USGS study is the first of its kind for Delaware, providing a comprehensive, baseline understanding of which PFAS are present and at what concentrations in well water throughout most of the state,” Reyes said.
Ongoing EPA efforts are aimed at better understanding the potential health effects of PFAS exposure over long periods of time, especially in children.
This is the third time since 2000 the USGS has sampled these specific wells — or a well in close proximity if the original well was no longer available — but it’s the first time they were tested for the presence of PFAS.
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With PFAS being an emerging concern and focus for the state, 18 types of PFAS identified by the EPA as some of those commonly detected in drinking water were added to the list of select chemicals included in the most recent USGS study. Sampling was done between August and November 2018.
The pervasive nature of PFAS stems from its use in a range of consumer and industrial applications, such as firefighting products, cookware, pizza boxes, carpets and stain repellants.
Of the wide variety of PFAS, there are only two types banned in recent years.
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The USGS conducted this study in cooperation with the Delaware Department of Natural Resources and Environmental Control and the Delaware Geological Survey.
“Both the DNREC and the Delaware Department of Health and Social Services continue their ongoing work to address PFAS in the state’s drinking water,” said the USGS in a statement on the data.
