The arsenic limits are unscientifically low and came about as part of a campaign to stop mining. Many parts of the world have natural environmental levels far e

The arsenic limits are unscientifically low and came about as part of a campaign to stop mining. Many parts of the world have natural environmental levels far exceeding these limits with no discernible impact on human health. Which makes sense since arsenic is a necessary micro-nutrient, albeit poorly understood, with a profile similar to selenium -- also highly toxic but also necessary in trace quantities, often from the water supply. The 3 ppb (or 10 ppb) limit the EPA wanted to use is pure scaremongering and is essentially unachievable in some geographies.