There is substantial evidence that arsenic is a required micronutrient in all mammalian biology. This is not even controversial, you can reliably induce deficiency syndromes in a broad spectrum of animal models, and the operative pathways exist in humans. The effect was first observed in animal husbandry in parts of the world with very low background arsenic levels.

It has the same toxicity and micronutrient profile as selenium, another extremely toxic but nonetheless essential micronutrient. Unfortunately, activists with an unrelated agenda have been spreading unscientific misinformation about arsenic to advance that agenda.

Same story as fluoride outrage actually. Being anti-science is fashionable and most people are ignorant about chemistry.

It is one thing that makes me glad I am no longer a practicing chemist.