The study found that individuals with diabetes had higher levels of arsenic in the urine compared to individuals without diabetes. The results are published in the August 20, 2008, issue of JAMA.

"Our findings suggest that low levels of exposure to inorganic arsenic may play a role in diabetes," said Ana Navas-Acien, MD, PhD, lead author of the study and assistant professor with the Bloomberg School's Department of Environmental Health Sciences. "While prospective studies are needed to establish whether this association is causal, these findings add to the existing concerns about the long-term health consequences of low and moderate exposure to inorganic arsenic."

Inorganic arsenic is found naturally in rocks and soils. In the U.S., most exposure to inorganic arsenic comes from contaminated drinking water. Foods such as flour and rice can also provide small quantities of inorganic arsenic, particularly if grown or cooked in areas with arsenic contamination in soil or water. Seafood is a source of organic arsenic compounds that have little or no toxicity.

Researchers examined randomly selected urine samples taken from 788 U.S. adults 20 years or older that participated in a 2003 ”2004 National Health and Nutrition Examination Survey. The results were adjusted for diabetes risk factors, including body mass index and for organic arsenic compounds found in seafood.

In the U.S., approximately 13 million people live in areas where the concentration of inorganic arsenic in the public water supply exceeds standards established by the U.S. Environmental Protection Agency, primarily in the West, Midwest and Northeast regions. Dietary intake of inorganic arsenic in the U.S. ranges from 8.4 to 14 micrograms per day for various age groups.

The authors concluded that given widespread exposure to inorganic arsenic from drinking water worldwide, clarifying the contribution of arsenic to the diabetes epidemic is a public health research priority with potential implications for the prevention and control of diabetes.

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The researchers say U.S. government limits for drinking water are 10 micrograms of arsenic per liter, which is exceeded in the water consumed by 13 million Americans living mostly in rural areas that rely on wells to bring up ground water.

This applies to many other countries and arsenic contaminates drinking water for millions of people in Bangladesh, parts of Central Europe, Chile, Argentina and the western United States, where ground water is the source of drinking water and the land has higher concentrations of arsenic.

Estimates suggest that 7.8 percent of Americans have diabetes, although some do not know it and at least 90 percent of cases are the type 2 variety and Dr. Navas-Acien says arsenic may play a significant role in diabetes incidence.

Arsenic can accumulate in the body, and can affect the body's ability to use insulin and perform the vital task of converting blood sugar into energy by blocking receptors, which allow glucose to enter the cells.

The research is published in the Journal of the American Medical Association.