I am guessing that some of those on my emailing lists might want to argue your comment about “there is NO safe level of arsenic“.
DOSE is certainly important and “Alles ist Gift” (everything is poison at some dose).
So, … this returns us to the old argument, or the two camps of thought: “Linear No-Threshold Model” (LMT) versus “Threshold Model“.
My own personal anecdotal story: at our Tillamook farmhouse every year for 6 to 12 wks (1994–2o1o) we drank and bathed in the well water, … which was determined to have eight times the level of arsenic allowed by the EPA (also, 37.5 times the level of iron allowed by the EPA). After battling with the state/city/county legislature for more than a decade, our entire private road of farms got hooked up to city water in 2o1o (for a pretty price).
Hmmm, … this chronic exposure <<could>> explain my behavioral changes since 1994.
ADDED
To conclude this informative GEITP discussion of “toxic elements in our environment”, please check out https://www.youtube.com/watch?v=SmwlzwGMMwc
This is one of many humorous fantastic songs by Tom Lehrer (who was a mathematics major at Harvard-turned comedian, ….. making far more money on stage than as a mathematician/scientist).
Go figure.