The Environmental Protection Agency said Wednesday that it plans to weaken limits on some “forever chemicals” in drinking water that were finalized last year, while maintaining standards for two common ones.

Some environmental groups argue that the EPA can’t legally weaken the regulations. The Safe Water Drinking Act gives the EPA authority to limit water contaminants, and it includes a provision meant to prevent new rules from being looser than previous ones.

The Environmental Protection Agency will rescind and reconsider drinking water standards for four chemicals that have been linked to a range of illnesses.