Atom bombs are still going off every day (not going to get into that) + nuclear testing is still going on.
I doubt that most people at that time had exposure to Love canal and Agent Orange (minus those in the military who went to Vietnam, obviously), although now Monsanto is trying to engineer seeds that are resistant to the herbicide 2,4-D so that farmers will start spraying insane amounts of it on their fields...2,4-D is one of the two ingredients of Agent Orange.
But I do get your point. Actually I was thinking back further then the 1900s when many families still grew their own food and family farms were everywhere - and people actually knew how to grow crops. Plus all of the other things I listed 2 posts ago.