Leaded goddamn everything. Especially gasoline. It took damn near an act of God to stop that from being a thing, the guy who finally waged the war on leaded gasoline had to go through so many hoops to prove that it was the gas’s fault. He literally reinvented what a clean environment was. Seriously, he invented the modern idea of a clean room, because the stuff he had to work with at the time was woefully inadequate at preventing contamination from interfering with his experiments.

Also, and this is a really stupid fact, tornado slides. They used to be pretty ubiquitous, until one day two well meaning parents waged a Crusade against them that successfully accomplished literally nothing.

This one is especially telling. Basically, their kid fell off a tornado slide. If you don’t know what that is, look it up it’s just a slide that twists round in a spiral a few times. Their kid was on top of one being a kid, screwing around and not just sliding down it, fell off, whacked their head on something, and died tragically. So in an effort to protect other parent’s children, they waged a legal crusade to get tornado slides baned from playgrounds. They were successful and governments passed safety reforms for playground equipment, including the banning of tornado slides.

Unfortunately this had two secondary effects. Primarily, kids stop playing at the playgrounds. They were no longer fun, and the whole purpose of a playground being fun is to allow the kid to explore and develop a sense of risk assessment. Consequently, or perhaps incidentally, the second effect was that statistically the amount and severity of childhood injuries in the United States following the changes showed that there was literally no difference before or after the bans. Kids just found other ways to hurt themselves, at exactly the same ratio as before.

The entire crusade had been a futile effort to stop kids from suffering tragic accidents. Unfortunately for them there’s nothing you can do to prevent statistical outliers. By appealing to emotion rather than using data, they destroyed the prior appeal of playgrounds for children nationwide. I don’t know if any subsequent reforms have changed things again, if I remember correctly this all happened somewhere around the '80s or '90s. Whatever the case, we now have other issues with kids not playing around outside, mostly related to electronic devices. But it’s a good object lesson in why appeals to emotion are probably one of the worst logical fallacies there are.