Emails among U.S. government officials show the Trump administration trying to manage a potentially damaging report on a class of chemicals found to have polluted water supplies near U.S. military installations.

The exchanges, sent in January, reveal officials from the Environmental Protection Agency and Office of Management and Budget worrying over a yet-to-be-released study from the Department of Health and Human Services. The draft report from HHS indicated that exposure to the chemicals in question is unsafe in far lower amounts than EPA previously determined.

One OMB official warned of a "public relations nightmare" when the report is released. The emails were unearthed through a Freedom of Information Act request by the Union of Concerned Scientists. Three and a half months later, the report has yet to be made public.

The chemicals, widely known as PFOS and PFOA, were found in drinking water or groundwater in quantities that exceeded amounts deemed safe by EPA near 126 military facilities, the Department of Defense said in a study in May. The perflourinated compounds, present in a firefighting foam used by the military, have been linked in some studies to prostate, kidney and testicular cancer, as well as to fertility problems and developmental delays in fetuses and children, according to the Defense Department report.

The draft HHS report alarmed administration officials because it concluded there is a minimal risk associated with exposure to the chemicals at levels as low as 12 parts per trillion.

Those concerns are laid out in an email from James Herz, associate director for Natural Resources, Energy and Science at White House Office of Management and Budget, to EPA Chief Financial Officer Holly Greaves.