Even the name makes the problem seem intractable: “forever chemicals.” This group of per- and polyfluoroalkyl substances, broadly called PFAS, are persistent organic pollutants that don’t readily degrade and can affect human health, with links to liver problems, infertility, thyroid disruption, birth defects, hypertension, and many other harmful effects. They’re in our water, clothes, food, dust—even in umbilical cord blood—and there may be no safe level of exposure. Can anything be done?