View Comments 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 7-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.