WaterDangerous levels of arsenic found in many U.S. wells

Naturally occurring arsenic in private wells threatens people in many U.S. states and parts of Canada, according to a package of a dozen scientific papers published this week. The studies, focused mainly on New England but applicable elsewhere, say private wells present continuing risks due to almost nonexistent regulation in most states, homeowner inaction, and inadequate mitigation measures. The reports also shed new light on the geologic mechanisms behind the contamination. The studies come amid new evidence that even low doses of arsenic may reduce IQ in children, in addition to well documented risks of heart disease, cancer, and reduced lung function. The reports comprise a special section in the journal Science of the Total Environment.

“Arsenic is the biggest public-health problem for water in the United States — it’s the most toxic thing we drink,” said geochemist Yan Zheng, an adjunct research scientist at Columbia University’s Lamont-Doherty Earth Observatory who coedited the special section and coauthored some of the articles. “For some reason, we pay far less attention to it than we do to lesser problems.” Much long-term work on arsenic in the United States and southeast Asia has been done via an extensive program at Lamont-Doherty and Columbia’s Mailman School of Public Health.

An LDEO release reports that many rocks and sediments have inert, harmless traces of arsenic locked into them. In recent years, however, geologists have observed that some geologic formations can become enriched in arsenic, and certain chemical conditions may cause rocks to react with groundwater and liberate the element into aquifers. Since the 1990s, the problem has been identified in some seventy countries; it is worst in southeast Asia, where as many as 100 million people are exposed.