President Donald Trump signed an executive order on Monday that aims to slash regulations—an action, advocacy groups say, that puts lives at risk.

The order—the latest of a flurry since he took office—states that “for every one new regulation issued, at least two prior regulations be identified for elimination,” fulfilling a campaign promise he made.

“For fiscal year 2017, which is in progress, the heads of all agencies are directed that the total incremental cost of all new regulations, including repealed regulations, to be finalized this year shall be no greater than zero,” it adds.

Trump said before signing the order: “We’ll be reducing [regulations] big league,” adding “This will be the biggest such act our country has ever seen.”

Advocacy groups were quick to decry the executive order as “unworkable,” “as dumb as it gets,” and “dangerous” as it puts enforcement of acts like the Clean Air Act, Clean Water Act, and Food Safety Modernization Act in jeopardy.

What the order means, said Sierra Club executive director Michael Brune, “is that for every restriction on immigration or tax break for big oil companies that is put into place, Donald Trump will also be able to throw out two clean air and clean water safeguards.” He called it “shameless pandering” that “is willfully ignorant of Congressional mandates.”