Turning "environmental regulation" into a unified bloc that must be either supported or opposed in totality is a manipulative political maneuver and it should be forcefully rejected.
Regulations are not people, and they don't have rights. It is fair and reasonable to demand that environmental regulation justify its existence with hard, scientifically verifiable data or else get chopped. Clearly, banning leaded gasoline has that kind of justification, and therefore I'm strongly in favor of maintaining that ban and extending it wherever it isn't in place yet. The same reasonable standard should be applied to other regulations across the board.
You are (deliberately?) overlooking the elephant in the room: lobbies with money can distort the discussion.
Big tobacco knew for decades that smoking was bad but still managed to block restrictions in smoking. Oil companies knew lead was poisoning. Purdue knew Oxycontin was addicting. Facebook knows their product is toxic.