Ok, I agree with everyone that says "correlation does not prove causation".
But I do believe that it has been proven that lead is unhealthy, especially to children, in lots of ways.
Yes, aviation's contribution to lead pollution is minuscule compared to what cars and other sources used to contribute, and probably even what is being dumped into the air and water today from mining, manufacturing and other sources.
But are some people actually disputing that lead pollution is dangerous and that it does not need to be curtailed to the largest extent possible? Is that what I'm hearing, or is the argument more about the risk/benefit equation?
It seems that these types of arguments always devolve into "one or the other" when, as I said before, the answer is usually a little bit of both and we are just arguing about the ratio.