Aides to President Trump's embattled EPA administrator attempted to stop publication of a study into water contamination near military bases nationwide, including former naval bases in Bucks and Montgomery Counties, according to a published report.

The study would show that the chemicals — known as PFOA and PFOS — are dangerous to humans in much smaller quantities than the Environmental Protection Agency has previously said, Politico reported this week.

Tens of thousands of residents nationwide, including some across Philadelphia's suburbs, have had their drinking-water supplies tested based on the "safe" level the EPA set for consumption of contaminated water. Some have been drinking water laced with the chemical at the levels believed to be acceptable under the EPA standard.

When a Trump administration aide said the report would cause a "public relations nightmare," aides to EPA Administrator Scott Pruitt and the White House sought to block the study from being made public, according to EPA emails released to the Union of Concerned Scientists under the Freedom of Information Act.

"The public, media, and congressional reaction to these numbers is going to be huge," one unidentified White House aide wrote in a January email, according to Politico. "The impact to EPA and [the Defense Department] is going to be extremely painful."

The study, conducted by the Department of Health and Human Services, still has not been published.

Sen. Bob Casey (D., Pa.) on Tuesday said that if the Politico report is true, "the White House should stop blocking the release of this health study. People in Bucks and Montgomery Counties as well as areas across the country deserve to know the health risks their families have been exposed to."

In Bucks and Montgomery Counties, more than 70,000 residents who lived near former naval bases had tainted drinking water. More than 130 with private wells near Joint Base McGuire-Dix-Lakehurst in New Jersey were also contaminated.

All of them have had their water tested based on the EPA's current guidelines.

After the contamination was made public, the military agreed to provide filters for public drinking wells — but only if they contained levels of the chemical above the EPA advisory, which they did for some local private well owners. In Warminster, Warrington, and Horsham, the towns changed public water systems to ensure there were no chemicals in their drinking water. Switching water systems, however, caused residents' water bills to increase. And other public wells still contained lower levels of the contaminants, which residents said they feared would affect their health.

Veterans and former civilian employees of the bases — which were mostly closed before the contamination was discovered — have also expressed concern about the chemicals.

Nationwide, 564 public or private drinking water systems near military bases had contamination above the EPA advisory level as of August, the military said in a recent report.

The Department of Defense is in the process of testing nearly 400 military bases and has found contamination at dozens, as first reported by the Inquirer and Daily News in April 2017 and acknowledged publicly by the military for the first time in a March report this year.

PFOA and PFOS are not among chemicals regulated by the EPA; the agency called its OK-to-drink level a guideline. Some scientists, however, have consistently said that levels within that guideline may also be harmful to human health.

The White House referred questions about the issue to the Department of Health and Human Services, Politico said, which confirmed that the study has no scheduled release date. The EPA responded to Politico's report by saying the agency was trying to "ensure" that the response from the federal government was "uniform."