It's no biggy. Plenty of artists consumed way more heavy metals, 10000x more than kids licking legos. And most didn't become mad hatters or suffer any real issues. The limits we set in medicine are much lower than what may manifest as biological damage. Better safe than sorry, right?

Or they didn't realize they were ever exposed to toxins, and they just think they got moody over time or that poor memory they have is normal aging.

Same could be said for asbestos as well as the undiscovered but numerous carcinogens and toxins we currently use in mass quantities. Every century has some type of widely used, but toxic, chemical discoveries. This century won't be any different.