Map of the Day

Deborah Blum:

“Arsenic is the number one environmental chemical for human health,”  Joshua Hamilton tells me during a recent phone call. We’re talking about his latest research, a just-published study in PLoS ONE  which found that this naturally occuring poison causes harm in an astonishingly small dose — 10 parts per billion.
Hamilton’s study looked at arsenic’s effect on mother mice and their offspring. But he chose the 10 ppb dose for a very human reason. It’s the safety standard the U.S. Environmental Protection Agency sets for arsenic in drinking water. Why does EPA need such a standard? Because an estimated 25 million Americans (mostly on private well systems) drink water contaminated by arsenic-rich bedrock. (I’ve put an arsenic map of the United States at the top of the post. Note that micrograms per liter is the same thing as parts per billion. This tells you that a lot of private wells — which are not held to public water supply regulations — run above the EPA standard.)
Global estimates of people drinking arsenic-contaminated water can run as high as half-a-billion people — and can also involve far more dangerous concentrations than in the United States. The classic — and tragic — example comes from  Bangladesh, a situation I described a couple years ago in a post called How to Poison a Small Country. In the 1960s, attempting to combat a cholera epidemic, aid agencies hit upon a plan of drilling wells across Bangladesh, tapping into bacteria-free ground water. They later realized that they had tapped into one of the most arsenic-contaminated aquifers on the planet, creating what WHO would later call the greatest mass poisoning of a human population in world history.

That's a pretty hot spot up in Wisconsin.