Tom Kennedy learned about the long-term contamination of his family’s drinking water about two months after he was told that his breast cancer had metastasized to his brain and was terminal.

The troubles tainting his tap: per- and polyfluoroalkyl substances, a broad category of chemicals invented in the mid-1900s to add desirable properties such as stain-proofing and anti-sticking to shoes, cookware and other everyday objects.