Well you can't really undo lead poisoning. Nor microplastics, etc. Once those have gotten into a population that's just how the population's gonna be. So it makes sense that there's nothing to do about a lead-poisoned population other than stop adding more.
> So it makes sense that there's nothing to do about a lead-poisoned population other than stop adding more.
Well the criticism is, of course, that lead poisoning, in most cases was the government doing it (e.g. Flint, and lead pipes in Europe). As for "nothing to be done" ... well, no. But that still leaves the government responsible for the damage (which in cases they had a private party to convict was lifetime care + damages).
Of course, governments decided, immediately, they weren't responsible.
Lead poisoning either kills you quickly (large doses, or you're already an adult) or turns you into an idiot, permanently (young kids, including in the womb)
> microplastics ...
No version of microplastics damages kids' brains, so it doesn't compare, really.