I’m not trying to be combative, but I don’t think we’re on the same page.
That website not making the point that drinking 20 gallons of heavy water would kill you, but that replacing your normal dose of light water with heavy water would kill you eventually due to differences in bond strengths (or something like that, I’m no chemist).
Not that this question is even important to the article really, except that I would find it pretty interesting if—as I interpreted the article to claim—the ice on comets tends to be comprised of water containing mostly deuterium, or some other variant.
It just lead me to wonder whether life would have been possible in a world containing greater proportions of deuterated water, or if we would have just evolved differently to utilize it normally. But then you said it wasn’t toxic, and I thought it was, leading to my response.
Were you to replace any substance with something that is foreign, or intake any substance to excess, it is toxic.
But for all intents and purposes, in everyday life, the only practical difference is that heavy water (D2O or T2O) is radioactive.
Working at a heavy water reactor plant in Canada, where intakes of Tritium were expected, the course of action is to drink extra water, keep the kidneys flushing and active, because, chemically, Tritium behaved the same as light water. Monitoring was done via urinalysis.
But, I stand behind my contention that it is not chemically toxic. The only difference in the three is the number of neutrons present in the nucleus. All three have the same number of protons and electrons and it is the electrons that determine the chemical properties of an element.
As an aside, it is also my belief that we were created not eveolved.