interestingly enough, there is an argument to be made that the big increases in urban crime in the 70's-80's which have taken a few decades to fall back, line up with the increase in lead burden in children from the huge increases in the use leaded gasoline that were occurring during that period. Lead isn't good for brains, esp young ones. Things like poor development of impulse control follow.
There are a lot of environmental scares that pretty much just that, but I tend to believe that one was real and never has been fully recognized for the disaster it was. The combined political pull of big oil and the auto biz meant that no-one was ever going to be held to account for what happened or even look all that closely.