When Donald Taves discovered two kinds of fluoride in his blood in the late 1960s, he immediately knew something was wrong.
Everyone assumed that blood contained just one type of fluoride, a naturally occurring form that health officials added to drinking water to prevent cavities. But levels in people’s blood didn’t seem to relate to those found in their water supply. Taves, then a researcher at the University of Rochester, set out to find out why — and discovered that his blood contained a second form of fluoride. With colleagues from the University of Florida, he then analyzed additional blood samples, from over 100 people living in five different US cities. The researchers found this second form — which he suspected was a synthetic, highly stable form made by adding fluorine atoms to a carbon chain — in their blood, too.
Members of this family of chemicals, known as per- and polyfluoroalkyl substances (PFASs), repel oil, water, stains and heat, thanks to the unique properties of their seemingly immortal fluorine-carbon bonds. They’ve been manufactured and added since the 1950s to a dizzying array of consumer and industrial products, including carpets, fabric, cosmetics, outdoor gear, nonstick cookware, microwave popcorn bags, airplane hydraulic fluid and firefighting foams.