Betty Rivas prepares breakfast for her family Thursday, Feb. 23, 2023, in Commerce City, Colo. Rivas was startled by a letter telling her that the drinking fountains her 8-year-old used at school weren’t safe. PFAS stories had been in the local news and the school district told families to use bottled water. (AP Photo/Brittany Peterson)

The Environmental Protection Agency is expected to propose restrictions on harmful “forever chemicals” in drinking water after finding they are dangerous in amounts so small as to be undetectable. But experts say removing them will cost billions, a burden that will fall hardest on small communities with few resources. Concerned about the chemicals’ ability to weaken children’s immune systems, the EPA said last year that PFAS could cause harm at levels “much lower than previously understood.” The expected announcement is intended to address this growing gap between health science and regulation.