Asbestos, lead paint, cigarettes, heroin(perscribed generously for basically whatever the doc felt like), "Radithor" (patent medicine containing radium-226 and 228, marketed as a "perpetual sunshine" energy tonic and cure for over 150 diseases), bloodletting, mercury treatments for syphilis, tobacco smoke enemas (yep that was a real thing), milk-based blood transfusions.
Didn't understand those either and used the fuck out of them because "the experts" said we should.
This is why I believe we should only listen to amateur opinions on everything, experts simply lack historical credibility. For example I've recently purchased a healing crystal (half off) for only $5000 dollars! It cleared up the imbalanced energies my street guru told me about right away.
I would never have been made aware about the consequences of imbalanced energies in the first place if I had asked an expert instead. They probably wouldn't even suggest an immediate solution to the problem like my reliable street guru always does! Something to consider.