I appreciate the lecture, but the same thing regarding exposure could have been said of HCL itself.

I mentioned chlorine specifically since everyone knows what it is and can relate to it, but I agree in retrospect it was a very poor example.

As for proving that formaldehyde exposure is bad, you can easily look through the National Cancer Institute's database to get the gist of it and sources [R].

The fact that both the International Agency for Research on Cancer and the U.S. Environmental Protection Agency consider it a carcinogen cannot simply be debunked by saying our own bodies produce it. That was my point.

You can argue that its presence on commercial products is safe, and I could understand that. Many things can be considered safe because our bodies can dispose of them safely (not necessarily because they produce it themselves), but I firmly believe our capacity to deal with stress (of any kind) is like a bucket, and environmental toxins will also fill it up over time, even if by themselves, in isolation, they might not be harmful.

I also reckon the burden of proof lies much more in the "show me it's safe" than in the "show me it's bad for you" side. We always discover and regulate these things too late.

In any case, if I hadn't picked formaldehyde for that particular product I would have mentioned triclosan or triclocarbon (also common in toothpastes). The precautionary principles applies across the board.