DOVER, Del. (AP) — The extent of contamination in some public drinking water supply wells in Delaware from certain manmade chemical compounds associated with cancer and other health problems is worse than what was discovered several years ago, but state and federal officials have not alerted the public to their findings.

An Environmental Protection Agency spokesman confirmed in a response to a question from The Associated Press that 10 of 14 public supply wells in a seven-square-mile area surrounding the New Castle County Airport have been found with levels of fluorinated chemicals known as PFAS that exceed the EPA’s lifetime health advisory levels.

The contamination involves all four New Castle city public wells and six Artesian Water Co. wells. PFAS levels in the city wells ranged from 630 parts per trillion to 4,500 ppt, well above the EPA health advisory level of 70 ppt. Contamination in the Artesian wells ranged from 71 ppt to 1,340 ppt.

The city has about 2,300 water customers, while Artesian serves about 6,000 commercial and residential customers within the area of interest.

Officials said the contaminant levels involve water that is treated with carbon filters before it goes to customers, and that levels in treated water are within acceptable limits.

But unlike in 2014, when the discovery of PFAS contamination in three city wells and two Artesian wells led to an ongoing investigation by state and federal officials, no public notice was issued about the more recent findings.

EPA spokesman David Sternberg said in a email that any reporting or notification requirements are coordinated through the state Office of Drinking Water.

“Any public notification regarding contaminated drinking water is related to finish water (post treatment) not raw water (pre-treatment), ” he added.

That assertion, and Sternberg’s initial refusal to identity the specific wells involved “for security reasons,” are at odds with how officials responded in 2014. At that time, they identified both the specific wells that were contaminated and the pre-treatment contaminant levels, which ranged as high as 440 ppt for a chemical called PFOA, and 2,300 ppt for another known as PFOS.

“Any public notices issued for that situation were likely done out of an abundance of caution and to keep the public informed,” said Jen Brestel, a spokeswoman for the Division of Public Health.

The EPA said the latest sampling results are from 2019, but Artesian officials said the additional contamination was found years earlier in follow-up testing after the initial discovery of contamination in 2014.

Artesian officials noted that, unlike in 2014, when no PFAS treatment systems were in place, there was no need to report the later findings because the water was already being treated.

“If it’s in the source water and it’s being addressed, there’s really nothing with our customers, the public, to be addressed,” said Artesian executive vice president Joe DiNunzio. “We do submit finished water data to Public Health.”

The city of New Castle doubled the quantity of granular activated carbon in its PFAS filtration system from 40,000 pounds to 80,000 pounds in 2019, but water utility manager Jay Guyer explained recently that the move was a cost-savings measure to reduce the frequency of carbon changeouts and was not based on increased contaminant levels.

Meanwhile, state officials recently deleted PFOA and PFOS test results submitted by Artesian from Delaware’s “Drinking Water Watch” website. The two compounds also were removed from a list of chemicals that are tested in drinking water.

State officials explained that the chemicals are not currently regulated under the federal Safe Drinking Water Act and therefore do not have to be tested in public water supplies or reported to public health officials when contamination is found.

PFOA and PFOS have been used for decades in a wide variety of manufacturing and industrial operations and consumer products, including outdoor and protective clothing, food-packaging, carpet and nonstick cookware. PFOS has been an ingredient in firefighting foams commonly used at airports and military installations, including the New Castle County Airport and adjacent Delaware Air National Guard installation.

PFOA and PFOS are only two of hundreds of synthetic chemicals known as PFAS, which have been associated with health effects including high cholesterol levels, thyroid disease, certain cancers and pregnancy-related problems. They often are referred to as “forever chemicals” because they do not easily degrade and can remain in the human body for years, even decades.

The EPA has taken initial steps to begin regulating PFOA and PFOS in drinking water, but some states are not waiting. A handful have already set their own maximum contaminant levels for the two compounds, and lawmakers in Delaware and several other states have introduced legislation to do so.

“We need to keep our citizens safe now. We can’t wait,” said Rep. Debra Heffernan, a Newark Democrat.

Heffernan is chief sponsor of a bill directing Delaware health and environmental officials to establish maximum contaminant levels for PFOA and PFOS and to conduct a statewide survey of other PFAS in drinking water. The bill passed the House unanimously and awaits action in the Senate.