January 07, 2008
Thursday

A chicken-feed additive containing arsenic and used to produce pinker, healthier, bigger-breasted birds could cause human disease, according to a study.

The study is the first to link a human health risk to the feed additive that has been widely used since the 1960s by commercial chicken producers to control intestinal parasites, reduce stress, stimulate growth and improve the color of chicken meat.

Partha Basu, the study's lead author and associate professor in Duquesne University's Department of Chemistry and Biochemistry, said laboratory analysis reveals that the antibiotic arsenic compound roxarsone, which promotes the growth of blood vessels in chickens to produce pinker meat, does the same in human cell lines -- a critical first step in many human diseases, including cancer.

"This is a significant finding as it relates to potential human health effects from roxarsone," said Basu, who worked on the study with scientists from Thermo Fisher Scientific laboratories and the University of Pittsburgh's Department of Environmental and Occupational Health.

"We wanted to test if roxarsone, which increases pigmentation by forming more blood vessels in chickens, does the same in humans and the answer is yes," Basu said. "It's a process called angiogenesis, a common growth process, but also one that occurs in many diseases and cancers."

Results of the study have been published in Environmental Health Perspectives, an online journal of the National Institute of Environmental Health Sciences, which supported the study.

Although the effect of roxarsone on those who eat chicken is still undetermined, Basu said, chicken-farm workers are likely at risk because they could inhale dust containing arsenic from feed and waste. In addition, those who work with or use commercial fertilizers containing waste from chickens that were fed the arsenic additive could also be exposed by breathing the dust.

The National Chicken Council, a Washington-based trade organization for the poultry industry, wasn't aware of the study but maintained that roxarsone is safe and is approved by the Food and Drug Administration.

"The study is based on lab tests. There's nothing epidemiological about it," said Richard Lobb, a spokesman for the council, who emphasized that the study is not based on reports of actual illnesses. "It will need to be repeated and confirmed by other researchers."

Alpharma Inc., the global specialty pharmaceutical company that makes roxarsone, declined comment.

U.S. chicken producers use a total of 2.2 million pounds of roxarsone each year. About 70 percent of the 9 billion fryer chickens grown annually nationwide eat feed containing the additive, which also is used in turkey and pig feed.

More than 95 percent of the roxarsone fed to chickens is excreted unchanged in chicken waste, which is regularly applied as fertilizer on surrounding farm fields or used in commercial fertilizers.

The new study is a follow-up to one released by Basu and other Duquesne researchers last March that found the organic arsenic feed additive is chemically transformed into inorganic arsenic, a known carcinogen, much more quickly than previously thought.

Arsenic occurs naturally in the environment, but industrial discharges by coal-burning power plants, industries and some mining operations are closely regulated. Its use in pesticides and as a wood preservative has been banned due to health concerns and the difficulty in removing it from the environment.

Chronic exposure to inorganic arsenic is known to cause cancer and has been linked to heart disease, diabetes and declines in brain functions.

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