Just because people "know" something is safe doesn't make it so. Below a certain percentage increase, or with more long-term effects, public perception of the i

Just because people "know" something is safe doesn't make it so. Below a certain percentage increase, or with more long-term effects, public perception of the issues that might come with a common treatment could be overlooking things. We've known (for various confidence levels) that lithium salts are effective for some mood disorders since at least the 1870s (though there's various stories and one-off doctor recommendations that survive about lithium salts or natural water sources with high lithium levels being good for melancholy much older than that), then the FDA banned it in the 1940s due to the nasty discovery of lithium poisoning fatalities, and now we're using it again since 1970, with recurring blood tests to be sure you're not accumulating too much. We used lead regularly in all sorts of things until, surprise, lots of people often exposed to lead turned up with nasty health issues. We used asbestos all over the place until, decades after we started using it, we realized "hey, maybe all these easily-broken-off fibers that turn up in the shredded lungs of people might be related". We used syrup of ipecac for hundreds of years, until we concluded "I _think_ the side effects from the ipecac are probably worse than the thing we wanted them to expel".