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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 to be published next 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.
Many rocks and sediments have inert, harmless traces of arsenic locked into them. But in recent years 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 70 countries; it is worst in southeast Asia, where as many as 100 million people are exposed.
Largely unregulated private wells serve some 43 million Americans; previous work by the U.S. Geological Survey indicates that 6.8 percent tested nationwide violate federal standards governing arsenic in public water supplies. This could be interpreted to mean that some 3 million people are affected; but USGS hydrologist Joseph Ayotte, the special section’s other coeditor, says the distribution of high arsenic levels is spotty, so it is hard to extract a reliable number.
Continue reading at The Earth Institute – Columbia University.
Water well image via Shutterstock.
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