Political appointees at the White House and Environmental Protection Agency worked to block the publication of a federal study that found dangerous levels of toxic chemicals in water supplies, according to a new report from Politico.

The study was conducted by the Department of Health and Human Services (HHS) and showed that a specific class of toxic chemicals “has contaminated water supplies near military bases, chemical plants and other sites from New York to Michigan to West Virginia,” Politico reported.

But instead of making the results of the study public, EPA emails obtained by a Freedom of Information Act request from the Union of Concerned Scientists show political appointees tried to stop publication of the study, citing a “public relations nightmare.”

“The public, media, and Congressional reaction to these numbers is going to be huge,” an unidentified White House aide wrote in an email forwarded at the end of January, adding, “The impact to EPA and [the Defense Department] is going to be extremely painful. We (DoD and EPA) cannot seem to get ATSDR to realize the potential public relations nightmare this is going to be.”

The aide was referencing the Agency for Toxic Substances and Disease Registry, a group within HHS that conducted the study, which remain unpublished. The White House referred questions about the study to HHS, Politico reported. HHS then confirmed it has not scheduled a publication date for the study.

The chemicals in question are known as PFOA and PFOS, which the EPA has said are “fluorinated organic chemicals” used to “make carpets, clothing, fabrics for furniture, and paper packaging.” They are also in foam used to fight fires on airfields, a practice that explains why they have been found at unsafe levels at 126 military installations, according to a Defense Department report released in March.

The new study shows the chemicals, which have been linked to low birth weights, cancer, liver damage and thyroid problems, are dangerous at lower levels than previously understood. While previous EPA guidance warned against exposure at levels above 70 parts per trillion, the new HHS report said the chemical could be harmful for infants and breastfeeding mothers at just one-sixth of that level, Politico reported.

The chemicals were mostly phased out of production by 2015, according to an EPA report.  

After the White House aide sounded the alarm about the potential public relations consequences of releasing the study, EPA chief of staff Ryan Jackson coordinated responses between HHS, EPA and the Pentagon, Politico reported.

Jackson told Politico the EPA was helping to “ensure that the federal government is responding in a uniform way to our local, state and Congressional constituents and partners.”

Jackson’s boss, EPA administrator Scott Pruitt, is the target of more than 10 open investigations related to allegations he misused taxpayer funds and punished staff for raising concerns about his spending.