About four decades ago, when the Environmental Protection Agency was first trying to figure out what to do about lead in drinking water, Ronnie Levin quantified its damage: Roughly 40 million people drank water with dangerous levels of lead, degrading the intelligence of thousands of kids.

But new regulations were going to be costly and complicated. So, “instead of trying to deal with it substantively, they just tabled it,” Levin, a former EPA researcher, said of some of her colleagues at the agency in the 1980s.

One co-worker, though, leaked Levin’s analysis to the press, igniting a public outcry that pressured the EPA to act. And the rules it issued back then have stayed in place, with only modest changes, ever since.