Environmental doesn't necessarily mean it is something we've done to the environment. Even if the world's environment were reverted to "untouched by humans" status, you can still get melanoma from too much sun exposure, and that would still be an "environmental" factor.

Unhealthy eating (especially very salty/spicy/fermented foods), alcohol use, and so on also classify as environmental factors. But they are not caused by pollution or chemical-laden foods, merely bad life choices. Copious quantities of red meat isn't good, organic or no.

I don't meant to imply our bad handling of the planet causes no cancer, it certainly does. But it does not cause anywhere close to 90% of cancer cases. Not by a long shot.