Arsenic, chicken feed and the FDA are three terms not normally seen together in health articles. Here’s how such an alignment can happen… An arsenic-containing drug used in chicken feed will no longer be sold in the U.S. after FDA researchers detected a more dangerous form of arsenic in chickens fed the chemical.

The agency announced Wednesday that Pfizer subsidiary Alpharma will discontinue U.S. sales of 3-Nitro, a drug fed to chickens to help them gain weight and to prevent an intestinal disease called coccidiosis. Chickens that had been given the drug, which contains organic arsenic, had higher levels of what’s known as inorganic arsenic in their livers, compared with chickens not given the drug.

First, the key point of the announcement: “FDA officials stress that the levels of inorganic arsenic detected were very low and that continuing to eat chicken as 3-Nitro is suspended from the market does not pose a health risk.”

Second, the Associated Press article on the matter points out that many poultry producers no longer give their birds the drug.


In a Q&A on the drug, the agency says this about the difference between inorganic arsenic and organic arsenic:

“The inorganic form is more harmful than the organic form, and has been found to be a human carcinogen. Organic arsenic is not known to be carcinogenic. Organic arsenic is the form of arsenic that is the active ingredient in approved arsenic-based animal drugs, including 3-Nitro.”

The fact sheet then goes on to say that, at the time of the drug’s approval, researchers thought the organic arsenic in the drug was eliminated from birds’ body in the same form, as organic arsenic.

Researchers’ ability to detect inorganic arsenic in edible tissue – and thus their understanding of the matter – has since changed.


Pfizer will stop selling the drug after 30 days to allow time for animal producers to find new medications. 3-Nitro, a.k.a. roxarsone, is the most common arsenic-based animal drug, but similar drugs have been approved for poultry and pig feed. Of those, only nitarsone is marketed.

healthkey@tribune.com

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