Cut Crime, Boost Growth, Get Rid of Lead

When I was a kid, adults told me that the Roman Empire fell because they used lead plumbing. Lead poisoning made them all go crazy, after which they surrendered the keys to the Visigoth conquerors. It was years before I learned that the grownups were pulling my leg. And yet now, in a “truth is stranger than historical fiction” sort of way, I’m discovering that lead pollution is actually an important issue in our modern Rome, the U.S.

The basic reason for lead’s importance comes from biology -- when the heavy metal gets in your body, it wrecks your brain. It lowers your IQ for your entire life. In children, just a little lead in the blood can cause intellectual impairment. Of course, IQ is just one simple, convenient measure of mental ability, but it’s a good bet that whatever lead does to make us dumber also impairs functions like self-control, attention, judgment and rationality.