Arsenic is one poison to which our bodies can easily adjust. Given in a small dose, it stimulates our liver to make the antidote -- alpha lipoic acid (made from sulfur containing substances like cysteine and methionine). And this substance is an important part of our energy production systems. With gradually increasing doses of arsenic, or constant exposure, our bodies can eventually tolerate doses a lot higher than what can instantly kill someone who has never been exposed to it.
So personally, I would not worry about this arsenic in our food. I may even consider it good for us. If arsenic is not enough to kill, then it's somehow beneficial. Our livers will be stimulated and our metabolism will improve.
There was a metabolic stimulant given to animals that does contain arsenic. And it's been around when I was a student in the '70s. And it works! (I wonder why it doesn't come up in a Google search?

Maybe it's no longer in the market?)
Arsenic trioxide (a pollutant) is also finding its uses against cancer (brand name: Trisenox -- we now have a pollutant being sold as a drug

). In fact, if there's a chemo I would accept for cancer, it would be this. I know there can be no toxicity if the body is given time to adjust to it, or if alpha lipoic acid is given simultaneously. Unfortunately, as with any drug that isn't harmful, it's having difficulty gaining popularity.
Gerry