Many US wells tainted with arsenic

According to the authors, arsenic is the biggest public-health problem for water in the United States-- the most toxic thing we drink -- yet 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 Columbia's Mailman School of Public Health and Lamont-Doherty, part of the Earth Institute at Columbia.

Since the 1990s, the problem has been identified in some 70 countries; it is worst in southeast Asia, where more than100 million people are exposed. Largely unregulated private wells serve some 43 million Americans, where according to a U.S. Geological Survey 6.8 percent tested nationwide violate federal standards governing arsenic in public water supplies. Hot spots are in many states, with patches breaking out through New England, where 20 percent of wells in eastern New England are above limits, affecting some 80,000 people in Maine alone; the contamination rate in the central part of the state is 45 percent. Others affected are in the Great Lakes area, the Pacific Northwest and California, and across the western states into Texas. In 2001, the U.S Environmental Protection Agency lowered the permissible standard from 50 parts per billion down to 10. Public water supplies serving more than 25 people are supposed to meet that standard, and most do--some, by filtering water if necessary. But many small rural public utilities are still in violation, mainly due to cost.

Risks of heart disease and lung, skin and bladder cancers are well documented above the 10-parts-per-billion federal standard. Last year, a Mailman School of Public Health study led by Dr. Graziano, professor of Environmental Health Sciences, found that even subtler traces--5 parts per billion--took 5 or 6 points off the IQs of children who were studied. Maine state officials say that 20 percent of the state's wells may violate this lower level. "The risk for pregnant women and children is much higher. We're hoping that recognition of the potential consequences for children may be a turning point in getting more action," said Graziano, who is also a pharmacologist. New Jersey, one of the few states to have any regulations regarding arsenic, has already lowered its limit to 5 parts per billion.

In conjunction with the Maine Geological Survey and Maine Center for Disease Control and Prevention, the Columbia team is now embarking on a project to test ways to motivate well owners in one county to test their water. Maine legislators are also considering a law requiring that a well be tested whenever a house is sold.

Special Section of Science and the Total Environment