Arsenic's use in chicken feed troubles health advocates

By Tom Pelton
Baltimore Sun
Mar. 10, 2007

POCOMOKE CITY - Carole Morison steps into a vast metal building where 27,200 chicks cluster in darkness around feeding machines. Pipes pump a gray, gravelly mush into round steel bowls.

Along with the corn, fat and protein being snapped up by the young birds is Roxarsone - a feed additive made from arsenic. Perdue Farms requires Morison to feed it to her chickens to fatten them and fight parasites.

"It's very disturbing to me that people are being exposed to this arsenic, but we don't have a choice - we have to feed the chickens what the company gives us," says Morison, a contract grower who has been raising chickens on her Eastern Shore farm for more than 20 years. "Farmers spread manure with arsenic in it all over their land as fertilizer, and we don't know what the risks are."

Morison, director of a farm workers rights group called the Delmarva Community Alliance, is joining public health advocates in calling on the poultry industry to stop its practice of adding arsenic products to chicken feed. They say the toxic element gets into chicken meat in trace quantities and can seep into farm fields and drinking water, although the evidence for this is inconclusive.

The U.S. Food and Drug Administration has approved the feed additive since 1944, saying there is no evidence it threatens the public's health. But the European Union has refused to allow the use of Roxarsone, saying there is no proof that even trace amounts of arsenic in food are safe.

The largest poultry producer in the U.S., Tyson Foods, announced last spring that it is no longer adding arsenic compounds to chicken feed, joining at least two other chicken producers that don't use it.

Now a new study has raised further questions about the practice. A Duquesne University biologist has found that most of the arsenic passes right through the chickens and becomes more toxic than previously assumed when combined with bacteria in manure.

To fight diseases

Maryland-based Perdue Farms, the largest poultry company in the East, says its use of Roxarsone helps protect chickens from parasitic diseases. The company has argued that consumers shouldn't worry, because the form of arsenic often found in chicken feed - organic arsenic - is harmless, unlike the poisonous form known as inorganic arsenic.

Julie DeYoung, vice president of corporate communications for Perdue, said yesterday that the company has been reducing the amount of Roxarsone used in its feed. Less than half the flocks receive it today, she said, though the company continues to believe it is harmless.

"The FDA has said this product is safe and effective," DeYoung said. "There have been numerous studies that show, over 20 years of application of poultry litter, that there is no impact on the environment."

But the study by Duquesne University biologist John F. Stolz found that bacteria in chicken manure quickly transforms the safer variety of arsenic found in Roxarsone into the dangerous, inorganic variety.

Because of these health risks, Stolz said, poultry companies should reconsider their use of Roxarsone as a feed additive. About 70 percent of the 8.2 billion broiler chickens produced in the U.S. in 2000 were fed Roxarsone, according to the journal Environmental Science & Technology.

"Do we care if farmers are getting exposed to arsenic? I do," said Stolz, whose study was published in the journal in January. "If it were essential in raising chickens, that would be one thing. But it's not. There are a number of poultry companies that are successfully raising chickens without it."

The FDA is examining Stolz's study but continues to believe that Roxarsone is safe. "FDA has no data to suggest that there have been any adverse health effects in humans due to the use of Roxarsone in chicken feed," the agency said in a written statement.

Arsenic is a naturally occurring element, but, like mercury, its origin in Earth's crust doesn't make it healthy to eat. The U.S. Department of Health and Human Services describes inorganic arsenic as a deadly poison at high doses, and in lower concentrations as a cancer-causing agent.

At least one study suggests that arsenic in small amounts makes it into the food people eat. The Institute for Agriculture and Trade Policy, a Minneapolis-based nonprofit, released a report in April showing that trace levels of arsenic remain in the meat of chickens fed Roxarsone. The group said 55 percent of 155 samples of chicken it bought from supermarkets contained arsenic, although not at levels that the federal government would classify as hazardous.

"It's totally unnecessary, so why eat chicken with arsenic?" said David Wallinga, the author of the report.

Whether arsenic from chicken feed is seeping into drinking water is a matter of debate.

A 2004 report by the U.S. Geological Survey found arsenic in about half of 29 wells tested in the Delmarva Peninsula, but in only one case at levels exceeding drinking water standards.

The researchers concluded that most of this arsenic came from natural sources, including an aquifer with the toxic element that stretches underground from Southern Maryland to St. Michaels and beyond.

But beyond this aquifer, the scientists also found elevated arsenic levels in surface water and shallow ground water in the Pocomoke River area of the Eastern Shore. This arsenic probably came from manure produced by the large number of poultry farms in this area, said Judith M. Denver, a supervisory hydrologist for the U.S. Geological Survey.

Denver said it's unlikely that people in the area are drinking the arsenic, because their wells are usually fairly deep and protected by layers of clay. "It's not likely that there's a lot of arsenic from poultry in drinking water because we don't drink surface water," Denver said.

Another study, by the Maryland Geological Survey, found arsenic levels violating federal health standards in 11 percent of 250 drinking wells sampled on the Eastern Shore and elsewhere in the state. But most of the arsenic was not in shallow wells where fertilizer was likely to seep in, said David W. Bolton, chief of the hydrology program at the state agency. This suggests that the arsenic was probably not from chicken manure but from the fossilized waste of ancient marine animals, he said. "It's definitely naturally occurring," Bolton said.

Exceeding standards

But toxicologist Ellen K. Silbergeld of the Johns Hopkins Bloomberg School of Public Health said a study that she and colleagues performed on hundreds of drinking wells in Maryland found higher arsenic levels near fields that had been spread with poultry manure. "We found that the practice of land-use chicken waste disposal is associated with elevated arsenic levels," Silbergeld said. The amounts found in the study were often in excess of federal health standards, she said.

Carole Morison, whose husband's family has been raising chickens near Pocomoke City for generations, sees the use of arsenic products as an example of the unhealthy industrialization of farming.

She said she earns about $4,000 a year from the chickens she raises in two 500-foot-long yellow metal buildings, but she doesn't own the birds.

Morison and her husband own the buildings and raise the chickens under contract with Perdue. The company dictates the diet and growing conditions, including the black-out curtains over the windows, she said. This induces the birds to sleep more and avoid wasting any energy they could use to get fatter.

Outside the chicken houses are two shiny cone-shaped bins, which she said the company fills every few days. She shows a "feed order shipment form" from Perdue for 51,900 pounds of feed that lists Roxarsone as an ingredient.

"They've bred the perfect chickens," Morison said, tiptoeing through mobs of eight-day old chicks on peanut-shell bedding. "They're bred to have larger breasts, because that's the desirable meat."

Behind the chicken houses is a shed, about 110 feet long and filled with hills of manure and the corpses of diseased birds. About twice a year, the waste is hauled away by a company that sells it for fertilizer.

"The question is, where does all the arsenic go, after it passes through the chickens?" she asked. "Is it washing off the fields into the water? Is it in the dust we breathe? We don't know."