The Nanny State wins one
Keep in mind that we were trying to do this today, the right would be adamantly opposed and insist that the founders are turning over in their graves because the nanny state was trying to strangle human liberty:
Over the past 50 years, after scientists realized that even minute doses of lead can have harmful effects, policymakers have been steadily trying to eradicate the stuff from the environment. In the United States, no one uses lead-based paint or fills up their cars with leaded gasoline anymore—those were banned back in the 1970s and 1980s. Lead levels in the air have dropped 92 percent since that time.
By most accounts, this was a spectacularly savvy investment. There’s ample evidence that lead exposure is extremely damaging to young children. Kids with higher lead levels in their blood tend to behave more aggressively and perform worse at school. Economists have pegged the value of the phase-out in the billions or even trillions of dollars. Some criminologists have even argued that the phase-out of leaded paint and gasoline was a major factor in the steep plunge in U.S. crime during the 1990s.
I remember watching a documentary about lead back in the 70s or 80s and thinking to myself that it must have something to do with the low test scores and other pathologies that everyone was up in arms about during that time. I'll never forget the sight of little toddlers eating chipped lead paint in a housing project. It was heartbreaking. The article above points out that recent studies have born that out.
Despite the improvements, there's still a lot to be done and there's quite a bit of resistance to it. I would guess that's not just because of ideology, but because of money as well, but the anti-science forces have made great strides in the last several decades. In a sane world we'd do a WPA thing and put people to work getting the lead out once and for all, since it's indisputable that it causes so much damage to our children. But we don't live in a sane world, do we?