The Trump administration feared it would be a “public relations nightmare”: a major federal study that concluded contaminated groundwater across the country, especially near military bases, was more toxic than the government realized. Political aides to President Donald Trump and Environmental Protection Agency head Scott Pruitt pressured the Agency for Toxic Substances and Disease Registry against releasing the results.

“The public, media, and Congressional reaction to these numbers is going to be huge,” an unidentified White House aide wrote, according to Politico. “The impact to EPA and [the Defense Department] is going to be extremely painful. We cannot seem to get ATSDR to realize the potential public relations nightmare this is going to be.” The study was not released.

That is, until Wednesday. Amid a media firestorm about the administration’s immigration policy, the ATSDR—a division of the Department of Health and Human Services—quietly published its 852-page review of perfluoroalkyls, or PFAS, which are “used in everything from carpets and frying pan coatings to military firefighting foams,” according to ProPublica. “All told, the report offers the most comprehensive gathering of information on the effects of these chemicals today, and suggests they’re far more dangerous than previously thought.”

These chemical compounds pose health risks to millions of Americans. They’re in roughly 1 percent of the nation’s public water supply, according to the EPA; in roughly 1,500 drinking water systems across the country, according to the Environmental Working Group. People who drink from these systems, even if their exposure to PFAS is low, now have a potentially increased risk of cancer; of disruptions in hormones and the immune system; and of complications with fetal development during pregnancy.