I can't help but be pedantic and point out that since IQ is normalized, their average IQ would be 100 whether or not they used lead. More philosophically, the

I can't help but be pedantic and point out that since IQ is normalized, their average IQ would be 100 whether or not they used lead. More philosophically, the condition of life is inherently susceptible to damage, so you practically have to draw the line at what level of damage you want to try and mitigate given the realities of the time. Do you want to be wrapped up, only breathing, eating, and drinking perfectly calibrated mixes of chemicals?