For decades, the chemical industry has shown a pattern of promoting its products to the public without disclosing their harms. We have now found that for chemicals known as PFAS, this industry practice has been harming our health once again. Per- and polyfluoroalkyl substances, known as PFAS, have been produced since the 1940s and are used in consumer products such as nonstick cookware, stain-resistant carpets, and waterproof clothing. Many studies have shown that PFAS persist in the environment and have contaminated drinking water, soil, and peoples’ bodies. The early producers of PFAS — 3M and DuPont — promoted them as a miracle of modern science.