Three corporations that produce a class of toxic substances commonly called “forever chemicals” have agreed to pay $1.2 billion to settle liability claims brought by municipal water agencies who say the companies knowingly contaminated drinking water supplies around the United States. DuPont and two spinoff companies, Chemours and Corteva, will pay into a fund to help remove the chemicals, known as PFAS, which can take centuries to break down in the environment. They’re used in everything from food packaging to cosmetics to fabrics and firefighting foam. PFAS have been found in the blood of nearly all U.S. residents and in a majority of people around the world. They’re linked to a host of health problems in humans, including liver damage, lowered fertility, asthma, thyroid problems, low infant birth weight and cancer.