Newswise — Chicken consumption may contribute significant amounts of arsenic to total arsenic exposure of the U.S. population, according to a study published today in the January issue of the peer-reviewed journal Environmental Health Perspectives (EHP). Arsenic is an approved animal feed supplement that farmers use to control intestinal parasites in chickens. The study indicates that at mean levels of chicken consumption, people may ingest 3.6"5.2 µg/day of inorganic arsenic from chicken alone. Drinking water, dust, fumes, and diet represent other forms of exposure. Inorganic forms of arsenic are classified as carcinogens, with chronic exposure (10"40 µg/day) associated with skin, respiratory, and bladder cancers.

Researchers from the National Institutes of Health (NIH) and the U.S. Department of Agriculture's Food Safety Inspection Service (FSIS) used national monitoring data from the FSIS National Residue Program to estimate a mean concentration of arsenic of 0.39 ppm in liver tissue between 1994 and 2000. Liver tissue was used in estimating the arsenic concentrations of the muscle tissue, which is the part of the chicken that is most consumed. Of the 5,000 chicken samples, 3,611 were young chickens and 1,582 mature chickens. By 1997, 99% of chicken was consumed as young chicken. "Arsenic concentrations in young chickens appear to be 3" to 4"fold higher than in other species categories sampled in the National Residue Program," the study authors write.

The researchers calculated the mean number of grams of chicken consumed by the U.S. population at the 50th, 95th, and 99th percentiles, using chicken consumption data from the 1994"1996 USDA survey "Continuing Survey of Food Intakes by Individuals." The estimated dose of arsenic ingested at each percentile of the population was calculated by multiplying the total amount of chicken consumed by estimates of inorganic and organic arsenic in chicken muscle tissue. The researchers calculated that a person consuming chicken at the mean rate of 60 g/day (approximately 2 ounces) might ingest 3.6"5.2 µg of inorganic arsenic per day, and 5.6"8.1 µg total arsenic per day, However, groups that tend to eat more chicken may face doses up to 10 times higher. For example, those in the 99th percentile—1% of the U.S. population who consume more than 350 g chicken/day—ingest 21"31 µg inorganic arsenic/day. For a person who weighs 70 kg (154 lb), this represents 0.30"0.44 µg/kg/day of inorganic arsenic, well below the Food & Agriculture Organization of the United Nations and the World Health Organization (FAO/WHO) Joint FAO/WHO Expert Committee on Food Additives tolerable daily intake of 2 µg/kg/day of inorganic arsenic, but a sizable portion (15"22%) of the tolerable daily intake.

"With chicken being such an important part of the American diet, and consumption continuing to increase, this study suggests the need for possible adjustments in estimates of safe levels of ingested arsenic from drinking water and other dietary sources," said Dr. Jim Burkhart, science editor for EHP.

The lead author on the exposure study was Tamar Lasky of the NIH. Other authors were Wenyu Sun, Abdel Kadry, and Michael K. Hoffman.

EHP is the journal of the National Institute of Environmental Health Sciences, part of the U.S. Department of Health and Human Services. The article will appear in print in the January issue of EHP. More information is available online at

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