This is always the case. The concern here is that the people who profit from being able to dispense harmful doses are also the ones that are responsible for monitoring its safety.

Unless it's bioaccumulative.

Just look at the wonders of methylmercury.

Or more positively, "dilution is the solution"

Dilution is a solution (in a figurative sense) if you know you won't want the substance later on.

In some ways, though, pollution is a materials technology problem, in that we don't know enough about materials technology to either use the pollutant directly or cheaply reprocess it into something we can use.