Depends on how much you're eating. They still contain chitin and human stomachs don't like chitin. You can end up with pretty severe stomach discomfort from eating a lot of them raw. Button and cremini mushrooms are actually the same species, and have pretty low chitin levels, but even someone with a pretty strong stomach can definitely overdo it with raw agaricus bisporus.

Is it common to eat raw mushroom? I've only even seen it in poorly made salads

The commercial button mushrooms are still carcinogenic when eaten raw. The reason you see them at salad bars is because in practice there is no way to sue the salad bar if you get cancer 20 years later or whatever. But it's still not a good idea to eat them raw.

The only two mushrooms people generally recommend trying raw are the beefsteak polypore and the caesar's amanita. But this isn't because they are healthier when eaten raw, but rather because they have some unique culinary properties that are considered worth the risk when consumed in small quantities.

Do you have a source? If you mean formaldehyde then I don’t think that really matters. That’s everywhere from a decent chunk of glues to wood. Chances are you are exposed to small amounts of it every single day.

It's agaratine, but unlike acrylamide, which is most definitely a human carcinogen, the jury is still out on agaratine. You can give rats cancer with it, but only at huge doses.

The more important consideration, from the limited reading I've done, is to limit consumption to cultivated mushrooms from reputable sources. Environmental toxins in raw mushrooms is a definite problem! But the white buttons you get at Safeway are no more likely to poison you than the potatoes or romaine you buy there.

(1) In mice.

(2) There's some question about whether cooking mushrooms even resolves the issue.

(3) The effect seems smaller than that of potatoes and other acrylamide carriers, which we know, end-to-end, to be causative of human cancer.

You do you, but mushroom carcinogenicity is not on my behavior-alteration list.

(I don't like raw mushrooms so it's easy for me to say this).

> (3) The effect seems smaller than that of potatoes and other acrylamide carriers, which we know, end-to-end, to be causative of human cancer.

Acrylamide, like many things, is known to be causative of cancer at extremely high doses. There is no indication that the levels found in food are harmful; it would be very difficult for a human to eat the levels of acrylamide shown to be harmful.

The list of things carcinogenic at doses two orders of magnitude larger than those found in food is large.

Meh. As far as I know, red meet is unambiguously carcinogenic, but that's not stopping many people from eating steak. I'll take my chances with mushrooms.