Sales of two drugs routinely fed to chickens for decades have been suspended in Canada after tests showed the birds contained small amounts of inorganic arsenic, a carcinogen.
Health Canada says there are no immediate risks to public health. But consumer advocates say the findings provide evidence that many of the drugs given to animals could be unsafe and that more action is needed to protect the public – particularly since similar drugs remain on the market.
The drugs, 3-Nitro-20 and Super Nitro-12, also known as roxarsone, and have been added to animal feed for years in order to combat parasites, as well as improve efficiency. The drugs are sold by Alpharma Canada, a subsidiary of Pfizer, and Dominion Veterinary Laboratories.
The drugs contain organic arsenic, which is much less toxic than inorganic arsenic. As a result, it was believed animals given the drug would pose no danger to humans.
But mounting evidence in recent years suggests organic arsenic can change into inorganic arsenic, raising fears it could remain in the tissue and cause potential harm to humans.
Sales of roxarsone in the US were suspended earlier this summer. In Canada, the suspension took effect Aug. 8.
Technical limitations meant researchers couldn’t measure the inorganic arsenic present in chicken muscle. But they measured the total presence of arsenic in the muscle and found it was lower than the total arsenic detected in the chicken livers.
The FDA noted that other arsenic-containing drugs are approved for use in animal feed, but they believe only one, nitarsone, is currently being marketed.
“This is a precautionary measure to remove any avoidable exposure to very low levels of inorganic arsenic in chickens treated with roxarsone,” Health Canada said in an advisory about the decision to suspend sales of the drugs.