May 4, 2004

 

 

Arsenic Used In Chicken Feed May Pose Threat

 

The widespread use of drugs to raise chickens in the poultry industry is exposing consumers to more arsenic than previously estimated.

 

Ellen K. Silbergeld, a prominent researcher at the Johns Hopkins Bloomberg School of Public Health, said arsenic-laced drugs designed to keep the birds healthy might pose an increased risk of cancer for consumers. It would also create manure that is contaminating Eastern Shore ground water.

 

In a paper published in the journal Environmental Health Perspectives yesterday, her research essentially disputed the conclusions of a U.S. Department of Agriculture study, released in the journal in January, which concluded that the drugs did not pose a serious health problem

 

The USDA had apparently underestimated the amount of arsenic found in chickens and used outdated data to estimate the health risks of ingesting arsenic.

 

"This paper had serious problems," Silbergeld said of the USDA report.

 

Her findings, based on data published by the USDA and other health experts, could have major implications for the Eastern Shore, where 10 percent of the nation's poultry is raised.

 

According to a spokesman for the poultry industry, concerns about arsenic in chicken feed are unfounded. Tests consistently show arsenic levels in chickens are well below standards set by the Food and Drug Administration.

 

"This study appears to be much ado about nothing," said Richard Lobb, a spokesman for the National Chicken Council.

 

But Silbergeld argued that arsenic in chicken feed creates potential problems in the meat produced and the ground water affected by the waste.

 

When chickens excrete arsenic in manure, sunlight breaks it down and it migrates to the soil where it can contaminate ground water supplies. She noted that Europe bans arsenic in chicken feed because of these health concerns.

 

"This is arsenic. We shouldn't lose sight of the sheer outrageousness of this," Silbergeld said.

 

Geologists have been closely monitoring arsenic levels in the Eastern Shore's water supply for years without finding serious hazards. Health officials in Queen Anne's, Talbot and Dorchester counties require new wells to be tested for arsenic because of concerns about contamination of the local aquifers, said David Bolton, program director of the hydrogeology section of the Maryland Geological Survey.

 

Tracy Connell Hancock, a USGS hydrologist, revealed that a recent U.S. Geological Survey study of the Pocomoke River Basin, found slightly elevated levels of arsenic in shallow layers of ground water that could be the result of tainted manure.

 

However, further studies are needed to prove any connection between the manure and the arsenic in the water.

 

Arsenic, which is a heavy metal and poison, can be naturally found in trace amounts in drinking water, dust, wood and some foods. Daily exposures to lower levels have been associated with skin, respiratory and bladder cancers.

 

In recent years, the Environmental Protection Agency has tightened standards for arsenic in drinking water, reducing permissible levels to 10 micrograms per liter.

 

On the other hand, arsenic is approved by the FDA as an ingredient in animal-feed supplements in agriculture. For decades, it has been used to promote growth and kill parasites, such as cocciodosis, which is a killer of chickens.

 

Chickens are fed arsenic in the form of an antimicrobial drug known as Roxarsone. The drug is given to them when they are young in order to stave off infections, as well as when they get older to help them grow. Most of the arsenic in Roxarsone leaves the animal as manure.

 

Researchers have known for years that some arsenic remains in the chickens. The USDA has also collected chickens from slaughterhouses to test their livers for arsenic since 1989.

 

In their study published in January, USDA researchers reported that arsenic levels in chicken were four times higher than those of other meats. Thus they concluded that not all of the arsenic they consumed was being excreted.

 

Eating 2 ounces of chicken per day - the equivalent of a third to a half of a boneless breast - exposes a consumer to 3 to 5 micrograms of inorganic arsenic, the element's most toxic form.

 

People who consume a lot of chicken might ingest 10 times that amount, according to the USDA study. The scientists assured that the levels were not high enough to raise serious alarms.

 

According to Silbergeld, the study did not go far enough. The USDA findings are based on industry assumptions about how arsenic levels in chicken livers translate into levels in the parts of the chicken that humans consume in quantity.

 

Tamar Lasky, an epidemiologist formerly with the USDA, now concedes that the estimates in her January study may have been low. Given its preliminary nature, she said, she might have erred on the side of caution.

 

"We were deliberately conservative. We didn't want to exaggerate the numbers and have people writing in the press that arsenic levels in chicken are huge," said Lasky, now with the National Institutes of Health.