(Beyond Pesticides, September 8, 2008) Inorganic arsenic may increase the risk of developing type 2 diabetes, according to a study published in the Journal of the American Medical Association by researchers at the Johns Hopkins Bloomberg School of Public Health. Common sources of inorganic arsenic exposure include dietary exposure, drinking water pollution, and contamination associated with arsenic wood preservatives such as sawdust, smoke, direct contact, and hazardous waste sites. The study found that individuals with diabetes have higher levels of arsenic in the urine compared to individuals without diabetes. 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.
â€śOur findings suggest that low levels of exposure to inorganic arsenic may play a role in diabetes,â€ť said Ana Navas-Acien, MD, PhD, lead author of the study and assistant professor with the Bloomberg Schoolâ€™s Department of Environmental Health Sciences. â€śWhile 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.â€ť
Dietary intake of inorganic arsenic in the U.S. ranges from 8.4 to 14 micrograms per day for various age groups. According to the United States Geological Survey (USGS), approximately 34,000 metric tons of arsenic were consumed in the U.S. in 2000. A 2004 study by researchers from the National Institutes of Health and the U.S. Department of Agriculture (USDA), found a high concentration of arsenic in young factory-farmed chicken. Small amounts of arsenic are added to chicken feed as a USDA approved supplement that controls intestinal parasites and is consequently transferred into the meat of the animals. (USDA-certified organic chicken it does not contain arsenic.) 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.
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 (EPA), primarily in the West, Midwest and Northeast regions. 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.
EPA began investigating pesticides containing inorganic arsenicals back in 1978 because of concerns that this family of chemicals presented risks of cancer, genetic mutation, and birth defects. In that review, EPA separated the use of inorganic arsenicals as wood preservatives from all other uses. In 1988, the agency banned almost all uses of nonwood-preservative pesticide products containing inorganic arsenicals because EPA determined that arsenic posed an unacceptable risk to workers and others exposed to arsenic. Yet, according to the Pesticide Action Network Pesticides Database http://www.pesticideinfo.org, there are five nonwood-preservative pesticide products containing the active ingredient arsenical acid and two products containing the active ingredient arsenic trioxide that are still registered for use by EPA today.
The inorganic arsenical wood preservative chromated copper arsenate (CCA) is still in use. Although, as of January 2004, most residential uses of this arsenic-based wood preservative can no longer be manufactured for decks and patios, picnic tables, playground equipment, walkways/boardwalks, landscaping timbers, or fencing- already existing residential CCA-treated wood and structures may continue to be sold and used. Industrial uses, such as utility poles, continue to be manufactured and put workers and the public at risk. The major source of contamination in surface waters and groundwater is wastewater from wood preserving facilities. Individuals living or working near wood preserving facilities are exceptionally susceptible to being exposed to surface water or groundwater, increasing their exposure and risk. These preservatives are also known to leach from previously treated wood. Children are also at risk if they put their unwashed hands in their mouths after touching soil or wood that is contaminated with these preservatives. As a result, public and environmental health continues to be compromised.
Arsenic has been linked to other health effects for decades. For example, arsenic is a known human carcinogen. Several studies have shown that inorganic arsenic can increase the risk of lung, skin, bladder, liver, kidney, and prostate cancer. The International Agency for Research on Cancer (IARC), the U.S. Department of Health and Human Services (DHHS) and EPA have determined that inorganic arsenic is a human carcinogen based on sufficient evidence from human data. High levels of arsenic in the body can also cause vomiting, diarrhea, blood vessel change, or death and can damage many tissues including nerves, stomach and intestines.
This is not the first time pesticides have also been link to an increased risk of diabetes. A 2008 study by the National Institutes of Health (NIH), including the National Institute of Environmental Health Sciences (NIEHS) and the National Cancer Institute (NCI), finds pesticide applicators with regular exposure to pesticides to be at a greater risk of type-2 diabetes. The study shows specific pesticides produce between a 20 and 200 percent increase in risk. Researchers looked at data from 31,787 pesticide applicators in North Carolina and Iowa over a period of five years. In that period, 1,171, or 3.7 percent, had developed diabetes, particularly for applicators in the highest category of lifetime days of use of any pesticide. The greatest risk was associated with the chlorinated compounds aldrin, chlordane, heptachlor, dichlorvos, trichlorfon, alachlor, and cyanazine. Another study from this year from University of Cambridge scientists studied the role that persistent organic pollutants (POPs), including pesticides, play in the risk of adult onset diabetes, as did a study in 2007 that looked at diabetic individuals who live close to hazardous waste sites containing POPs.
For information about arsenic treated wood, including how to identify it, limit your families arsenic exposure and use less toxic alternative materials, see Beyond Pesticides factsheet and Wood Preservatives program page.