Let's be clear here. Exposure to specific PFAS are associated with a variety of health effects, including altered immune and thyroid function, liver disease, lipid and insulin dysregulation, kidney disease, adverse reproductive and developmental outcomes, and cancer. And while eliminating the firefighting uses of these compounds (as an example) would cause some issues, 3M, after significant evidence of broad toxicity was discovered, went on to expand the market for these compounds from domestic cookware to , among other things, children's clothing and food packaging materials.
Comprehensive toxicological studies haven't been performed on every single compound in the family because the market has been flooded with over 12,000 individual compounds. That is a startlingly large number that given 3M's prior bad faith decision-making around this family of products immediately brings to mind the designer drug industry's habit of burying regulators in compounds tweaked to get around regulatory bans.
In industries that actually perform comprehensive testing before releasing a compound into the wild it costs on average between eight and fifteen million dollars to perform a full suite of toxicological tests. So if the onus to test is placed on regulators that's roughly one hundred and twenty billion dollars out of public coffers and several decades of lab time, to confirm 3M, Dupont, Chemours, et al haven't poisoned the planet.
So if I understand your position correctly you're claiming that since we have absolutely no evidence that any of these compounds are safe at any exposure level (as you said, no toxicology has been done on most of these) and despite prior bad faith acts by the companies involved, we should continue to extend the benefit of the doubt? I think not, and your own choice to install water filtration equipment into your own home suggest you aren't as convinced as you'd have us believe here.
To be clear my proposal is that going forward manufacturers be required to perform the same pre-clinical trials that pharma companies have to perform before they can apply to move to human trials. Retroactive testing of existing compounds is absolutely a nice stretch goal because I think we can all agree if something harmful to our families is making it's way into the ecosystem we'd like to know about it sooner or later. I am utterly untroubled by the notion that these additional requirements might impact shareholder value and see no particular reason why taxpayers should be expected to foot the bill for 3Ms shareholders.