The Environmental Protection Agency said on Tuesday that it would move away from requiring the testing of potentially harmful chemicals on animals, a decision that was hailed by animal rights groups but criticized by environmentalists and researchers who said the practice was necessary to rigorously safeguard human health.

The E.P.A. Administrator Andrew Wheeler said the agency plans to reduce the amount of studies that involve mammal testing by 30 percent by 2025, and to eliminate the studies entirely by 2035, though some may still be approved on a case-by-case basis.

The agency said it would also invest $4.25 million in projects at four universities and a medical center that are developing alternate ways of testing chemicals that do not involve animals.

“We can protect human health and the environment by using cutting-edge, ethically sound science in our decision-making that efficiently and cost-effectively evaluates potential effects without animal testing,” Mr. Wheeler said in a memo announcing the changes.