Playing Chicken with Arsenic

by Deborah Blum

If I were to pick an element that just about everyone recognizes as a poison, it would be arsenic (As). As a crumbly compound called “white” arsenic or arsensic trioxide (AsO3) it became so popular as a 19th century homicidal weapon – think Mary Ann Cotton and her 20 or so victims - that it eventually earned the nickname “inheritance powder.”

Its murderous qualities have given it a starring role in successful plays or movies (Arsenic and Old Lace), in best-selling stories of murder and betrayal, such as Dorothy Sayer’s 1930 crime classic, Strong Poison, or the more recent best seller, A Reliable Wife, with its wonderfully clinical descriptions of chronic poisoning symptoms.

In fact, a person can survive low-level arsenic poisoning for quite some time. But because of the way it damages cells – breaking apart the structures that allow cellular respiration - it turns out to be a quite dangerous carcinogen.* This has been demonstrated, especially, in countries where elemental arsenic permeates rocks at high levels and seeps into ground water. In Bangladesh, for instance, a program of well-drilling begun in the 1970s, literally created an epidemic of arsenic-related cancers.

And yet, for more than 60 years, the federal regulators have approved arsenic additives to poultry feed in the United States, partly to control parasites and partly because they chemically improve the appearance of packaged chicken and turkey parts, pinking them up for consumer approval. Those of us who prefer less obviously toxic material in our chicken buckets – and this includes me – have been advocating that we rethink this policy.

At the time, I wasn’t really expecting much to change. But as it turns out, the pharmaceutical company Pfizer, which makes the arsenic-laced additive roxarsone, has decided to suspend its sales. Why, you wonder, after all this time? It turns out that the industry argument for keeping the compound into chicken feed was that it was a better form of arsenic, not the ever-evil inorganic white arsenic, but a less toxic material rather tidily bound up with carbon (so, in this version, an organic compound) and hydrogen.

In fact, organic arsenic is definitely less hazardous than its inorganic (carbon-free) cousin. But tests now indicate that it may convert to the more lethal inorganic form as chickens and other fowl metabolize the compound. We know this because the U.S. Food and Drug Administration stepped up and ran some very nicely controlled tests showing that the bodies of birds that ate roxarsone-loaded food were consistently higher in white arsenic than those that ate feed without the additive.

As a result, Pfizer–or more specifically, its subsidiary, Alpharma, will suspend sales of roxarsone in 30 days while further tests are conducted. You’ll notice that no one is acting as if this is a major health emergency–which it isn’t. These are tiny levels of arsenic. Still–there’s a common sense health issue here–it’s always better with a metallic poison like arsenic to keep exposure to a minimum because it tends to stay in the body and could eventually add up to something more troubling.

Also, as it turns out, due to such additives poultry farms have been leaching out arsenic-contaminated wastes. The advocacy position has not been panicky, but it has been–rightly, I think–that this represents the unnecessary addition of a famed poison to the food supply.

So it’s gratifying to see the system work–or at least start to work–toward eliminating this particular additive. The FDA ran the appropriate tests; the pharmaceutical company responded as it should. The New York Times, however, pointed out that it could well be a rare triumph given our current political direction: The roxarsone study is a triumph for agency scientists but one unlikely to be repeated very often. The agency asked for $183 million in additional funds for food safety efforts next year, but House Republicans have instead proposed cutting $87 million.

Not that the House Republicans have ever listened to me, but my vote is for restoring those funds. Not to sound radical here but we need more research to help us navigate the world of industrial chemicals. Not less. And my vote is also that roxarsone stays off the market. Again, not to sound radical, but we need less arsenic in our diets. Not more.

Arsenic is so destructive that, in fact, researchers are considering several different mechanisms for the way it might cause cancer. It may create further destruction by generating reactive oxygen molecules. There’s some suggestion that it inhibits DNA repair enzymes. There may be other damaging pathways. All of which reminds us to approach with caution.

Poultry Farm photo credit  

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