The chemical compounds are all around you. They're on many fabrics, rugs and carpets, cooking pots and pans, outdoor gear, shampoo, shaving cream, makeup and even dental floss. Increasing numbers of states have found them seeping into water supplies.
There's growing evidence that long-term exposure to the perfluoroalkyl and polyfluoroalkyl compounds, or PFAS, can be dangerous, even in tiny amounts.
The Environmental Protection Agency is looking at how to respond to a public push for stricter regulation of the chemicals, in production since the 1940s. A decision is expected soon.
At hearings around the country last year, local and state officials asked the agency to set a maximum level for PFAS in drinking water nationwide. It will take that, officials said, to stop contamination and hold polluting parties responsible.
But it is more than a US problem. In Europe, Australia, Asia and elsewhere, regulators and consumers are confronting discoveries of PFAS contamination, especially around US military bases, where they're used in firefighting foam.
Industries use PFAS in coatings meant to protect consumer goods from stains, water and corrosion. They have phased out two of the most-studied versions of PFAS. Manufacturers say newer forms are safer and don't remain in the human body as long as older types. Some researchers said too little is known about them to be sure of that.
The 2005-2013 study monitored and tested nearly 70,000 people who had been drinking water tainted with PFOA, one of two kinds of PFAS since phased out of production. It found "probable links" between high levels of PFOA in the body and excessive cholesterol levels, ulcerative colitis, thyroid disease, testicular and kidney cancer, and problems in pregnancies.
The federal Agency for Toxic Substances and Disease Registry said last year that medical studies pointed to "associations" between the industrial compounds and those ailments, and also to liver problems, low birth weight and other health issues.
EPA-mandated testing of about 5,000 of the roughly 150,000 public water systems in the US that was completed in 2016 found dangerous levels of the same two PFAS compounds in 66 systems.
Contaminated materials are disposed of in landfills and sewage treatment systems. Firefighting foams are sprayed on the ground. The chemicals seep into soils, waterways, sediments and groundwater; some are incinerated, generating air pollution.
Many states are not waiting for the EPA, particularly regarding groundwater and, more recently, drinking water. New York is considering the toughest standard yet. In December, a state drinking water commission recommended a maximum limit of ten parts per trillion for PFOA and PFOS. Other states are trying to determine the extent of the contamination, according to the National Conferences of State Legislatures.
Unsurprisingly, the chemicals have turned up in a variety of wildlife species, including fish, bald eagles and mink. Cheryl Murphy, a Michigan State University biologist, said, "If it's affecting human beings, it will be affecting wildlife as well."