Okay, for the people who can't read between the lines and just resort to downvoting instead of actually being useful in a conversation.
1) The article is about childhood lead exposure on adult personalities.
2) He makes a comment about aviation and its current use of leaded gasoline ("contributes to higher than healthy lead in our environment") with the warning "this isn't a solved issue of the past".
3) This implies that the aviation industry and its use of leaded gas is in any way comparable to what we had before when everybody had daily contact with leaded gas.
4) Nobody has yet provided any evidence of the fact that aviation results in any appreciable exposure to lead for your average citizen.
5) This matters because the original article is not about environmental impact. It's about childhood exposure.
How is this so hard? I seriously question the ability of your average HNer to make logical deductions.