>Sometimes the costs aren't known in advance

3M knew for decades about the dangers of exposure to PFAS chemicals but didn’t inform the public.

During the 1970s and ’80s, it conducted studies on its US workers that showed PFAS building up in the bloodstream.

In 1977 the company determined PFOS was “more toxic than anticipated” in a study of rats and monkeys; in 1978 a monkey study had to be stopped after all the animals died within the first few days because the PFOS doses were too high.

In 1980, minutes from an internal 3M meeting said workers at the factory in Antwerp were told the chemicals had been found in human blood, but the company decided not to tell the government

I don't think it's a success story when a chemical company is pressured to stop producing something because of it's health effects after that chemical has made it into the blood of nearly every individual on the planet.

Expecting investors to vote against their own financial interests for the greater good is a terrible system. 3M investors only care because of the threat of lawsuits and other legal trouble; those are the mechanisms we need to improve. Stricter environmental rules and enforcement will force companies to reduce harmful externalities. The shareholder pressure is incidental.

Free markets are generally bad at handling pollution because the costs are so diffuse and long term; there's often a way to increase profits at the expense of someone else's health in a manner that can't be precisely quantified immediately.