I am the oldest of the “millennial” generation, and until 1980, cars burned leaded gasoline. The problem with lead is that when you burn it, the gasses get in the air and lead dumbs us down. Especially childrean. Economists convinced policymakers to force engineers to switch to unleaded gasoline because by lowering IQ, the whole economy would measurably suffer more than the cost to transition away. I feel blessed to be born in the generation after it was phased out, and suffer fewer neurological damage than generations before. Read more at the Smithsonian Magazine. What other toxins are still lurking in plain sight?