Re: I think a certain water bureau might not be very good at their job
The interesting thing about arsenic is that we need some, in the correct form, in our diet
Has that actually been proved?
Last time I read about it, the status of Arsenic as a trace element in higher organisms was unknown. It's omnipresent in the environment in small concentrations, so it's impossible to feed a rat on a completely Arsenic-free diet to see whether it develops a deficiency disease. On the other hand, there wasn't any known enzyme or other bio-molecule with Arsenic as an essential component.
Best guess was that Arsenic is an element that higher organisms have evolved to tolerate in low doses, because those doses are omnipresent.
I do know that certain micro-organisms are known to have evolved in Arsenic-rich waters to substitute Arsenic for Phosphorus in many (not all) of their biological pricesses. But drinking those same waters would soon kill a mammal, so any read-across is doubtful.