Scientists are ramping up research on the possible health effects of a large group of common but little-understood chemicals used in water-resistant clothing, stain-resistant furniture, nonstick cookware and many other consumer products.

Per- and polyfluoroalkyl substances are generally referred to by their plural acronym, PFAS. PFAS are resistant to water, oil and heat, and their use has expanded rapidly since they were developed by companies in the mid-20th century. Today, PFAS’ nonstick qualities make them useful in products as diverse as food wrappers, umbrellas, tents, carpets and firefighting foam. The chemicals are also used in the manufacture of plastic and rubber and in insulation for wiring.

In short, they are all around us. And as a result, they’ve found their way into the soil and, especially in some regions, into our drinking water.

“We’re finding them contaminating many rivers, many lakes, many drinking water supplies,” says Linda Birnbaum, director of the National Institute of Environmental Health Sciences and the National Toxicology Program. “And we’re finding them not only in the environment, but we’re finding them in people.”