[AnthonyMouse]

> The warning 'cancer-causing' has no effect.

Devil's advocate, it has an effect on some minority of people. Then the company loses sales and has the incentive to stop using the carcinogen if possible.

Your lifetime risk of getting cancer from that thing might have been one in a thousand, so you don't really care, but the company has ten million customers and getting them to change prevents 10,000 cancers.

This is a pretty good alternative to banning the thing. Because if there is a reasonable way to stop using the carcinogen, you don't want to be the company that has the cancer warning when your competitors don't. But if there isn't, maybe the risk is low enough that people make an informed choice to take the risk for the benefit of the thing with no better alternative, and that's fine too.