The US Environmental Protection Agency (EPA) Tuesday proposed a regulation to limit the amount of six different per-and polyfluoroalkyl substances (PFAS) in drinking water.

The regulation would set the maximum contaminant level at 4 parts per trillion for any individual PFAS or mixture of multiple PFAS. The proposed regulation would also require public water systems to monitor and check for PFAS, notify the public of the levels of PFAS, and reduce the level of PFAS in the water if it goes above the standards.

The proposed rule comes after the EPA announced it would receive $2 billion from the Infrastructure Investment and Jobs Act. The act earmarked funding that the EPA must use to “address emerging contaminants, like Per- and Polyfluoroalkyl Substances (PFAS) in drinking water across the country.” The funding is also available to states and local communities through a grant program.

The EPA anticipates the proposed regulation will be finalized by the end of 2023. If implemented, the regulation “will prevent thousands of deaths and reduce tens of thousands of serious PFAS-attributable illnesses.”

PFAS are “forever chemicals” that break down very slowly and build up over time in the environment. They have been found in consumer, commercial, and industrial products. According to the EPA, “PFAS are found in water, air, fish, and soil at locations across the nation and the globe.” Current research suggests that exposure to PFAS and build up in the body can have harmful effects on both human and animal health.