Pfizer is voluntarily suspending US sales of its Roxarsone product, which has been used as a chicken-feed additive by poultry farmers for nearly 70 years, after a recent FDA study of 100 broiler chickens found inorganic arsenic, a known carcingoen, at higher levels in the livers of chicken that were given the med compared with untreated chickens.

Roxarsone contains organic arsenic, which is a less toxic form of arsenic, but this can transform into inorganic arsenic, according to the FDA which, by the way, maintains levels detected were very low and continuing to eat chicken does not pose a health risk. However, chronic exposure is known to cause cancer and has been linked to heart disease, diabetes and declining brain function.

Organic arsenic is added to the feed of most roasters grown in the US, and inorganic arsenic is found in poultry waste, which is used as fertilizer. This increases the risk that inorganic arsenic contaminates surface water and groundwater in farming areas where chicken litter fertilizer is spread. Farmers use Roxarsone to combat intestinal parasites, improve meat color and weight gain.

The issue is not new, though. For several years, concerns have risen about the effect inorganic arsenic can have on food; the US produced about 8.7 million broilers last year, up from nearly 8.3 million in 2000, according to the National Chicken Council, a trade group for poultry producers (not their chickens). And five years ago, a study in Environmental Science and Technology found that organic arsenic added to chicken feed is chemically transformed into inorganic arsenic faster than previously believed (see here).

More recently, scientists at the FDA’s Center for Veterinary Medicine and the Center for Food Safety and Applied Nutrition developed an analytical method to detect very low levels of inorganic arsenic in edible tissue (read the summary of the study here). And so now, Pfizer’s Alpharma unit has agreed to suspend sales in 30 days. “We are pleased to announce that the company is cooperating with us to protect the public health,” says FDA deputy food commish Mike Taylor in a statement.

As for the poultry producers, the National Chicken Council has this to say: “Chicken is safe to eat. The Food & Drug Administration says it is NOT raising any alarms about consumption of chicken. 3-Nitro (Roxarsone) has been used to maintain good health in chicken flocks for many years. It is used in many, but not all, flocks…Chicken companies will continue to safeguard chicken flocks because healthy flocks are needed to produce healthful food for people.”

chick pic thx to barryskeates on flickr