Guest guest Posted November 27, 2007 Report Share Posted November 27, 2007 Food for Chickens, Poison for Man _http://scienceline.org/2006/09/20/env-wenner-arsenic/_ (http://scienceline.org/2006/09/20/env-wenner-arsenic/) A widespread farming practice is adding arsenic to the food chain. By Melinda Wenner, posted September 20th, 2006. When Gwen Cox raised broiler chickens for Pilgrim’s Pride from 2001 to 2004, she had to use poultry feed provided by the company. After a few incidents when she felt physically ill working with it—“I would start coughing and could hardly stop, or I’d get lightheaded or nauseous,†she remembers—she checked the feed labels and noticed that they listed roxarsone, an organic arsenic compound, as an ingredient. Concerned about her chickens as well as her own health, she asked Pilgrim’s Pride why she was being forced to use feed containing arsenic. “I was told to mind my own business,†she says. “[They told me] ‘it’s a microbe inhibitor and is proven to be safe in the quantity used in the feed.’ But you know some of this stuff is bad when the tickets instruct you not to feed it to any other animals due to it being proven fatal if ingested.†Pilgrim’s Pride, the second largest chicken company in the country, wasn’t doing anything uncommon: over 70 percent of all broiler chickens grown in the U.S. are fed roxarsone, according to a 2000 article published in the journal Poultry Science. Roxarsone prevents the growth of microscopic intestinal parasites called coccidia that frequently infect livestock, and it provides the added bonus of better growth—i.e., bigger chickens. (Despite repeated requests, Pilgrim’s Pride would not confirm whether it still uses roxarsone.) Roxarsone doesn’t disappear once chickens eat it. Some is distributed throughout the animal’s tissues, including the breasts, thighs and legs—meat that is later eaten by consumers. The rest is excreted unchanged in poultry waste. Ninety percent of this manure is later converted into fertilizer that can contaminate crops, lakes, rivers, and eventually drinking water. Little research, however, has investigated the public health consequences of this practice, which was banned in the European Union in 1999. Although several studies have looked at the levels of arsenic present in chicken muscle meat, and some have looked at crop soil contamination, the results have been inconsistent. None have determined how extensively this practice contaminates drinking water. “There’s been such a huge degree of regulatory attention paid to arsenic in drinking water, and yet here’s this very widespread practice that has a real potential of adding to drinking water contamination and yet nobody’s looking at it,†says Dr. David Wallinga, director of the Food and Health Program at the Institute for Agriculture and Trade Policy (IATP), a non-profit research and advocacy organization based in Minneapolis. Any increase in Americans’ levels of arsenic exposure is of great concern: The Environmental Protection Agency, which regulates drinking water, considers arsenic a class A carcinogen, meaning that data have definitively shown it to cause cancer. Other health effects from chronic low-level exposure include partial paralysis, blindness and diabetes. Although the EPA tightened its regulations for arsenic levels in drinking water this past January, lowering it from a maximum of 50 parts per billion (ppb) to 10 ppb, this new level still exceeds the agency’s recommendations for exposure to a carcinogen by a factor of 50. The EPA typically recommends that the amount of a carcinogen in drinking water should not cause more than one person in 100,000 to develop cancer as a result of drinking that water daily. But Americans who are regularly drinking water containing 10 ppb of arsenic are at a 50-fold higher cancer risk than this: in other words, one out of every 2,000 of those Americans is likely to develop cancer because of the arsenic in their tap water. And the EPA estimates that 12 million Americans are currently drinking water containing more than 10 ppb of arsenic—making their cancer risk even higher. The EPA isn’t meeting its own safety standard for arsenic because the recommended amounts “are set at a level which water systems cannot meet,†according to agency press officer Dale Kemery. After preparing a cost / benefit analysis, the EPA set its arsenic limits at a level that maximized risk reduction while minimizing cost to the consumer, he says. Where is all of this arsenic coming from? Most arsenic contamination arises from natural sources or from its former use in pesticides and wood preservatives. Though these uses have since been banned, the arsenic remains in the environment and is extremely difficult to remove. The poultry industry’s use of roxarsone, however, is one of the few easily preventable ways in which arsenic enters the food chain. Given that arsenic is already a significant health risk, many think that its use in poultry feed should be investigated and, if found to be a significant source of contamination, banned. This debate isn’t so cut and dried, however, because arsenic exists in both organic and inorganic forms, and experts disagree about the relative toxicity of the two. According to the FDA, which monitors the use of drugs in animal feed, organic forms of arsenic like roxarsone, which are bound to carbon and hydrogen, are “not considered to be carcinogens and are considerably less toxic than inorganic forms of arsenic,†writes agency spokesperson Michael Herndon in an e-mail. But the Agency for Toxic Substances and Disease Registry, part of the U.S. Department of Health and Human Services, states that “almost no information is available on the effects of organic arsenic compounds in humans.†ATSDR also says that high doses of organic arsenic can produce some of the same effects as inorganic forms. And although roxarsone starts as an organic molecule, it doesn’t stay that way. When a chicken eats feed containing roxarsone, most of it—about 150 milligrams over a chicken’s lifetime—is excreted unchanged in the chicken’s waste. After 30 days, the excreted roxarsone naturally converts into other forms of arsenic, including highly toxic inorganic forms like arsenite, according to a study published this year in Environmental Science & Technology. Inorganic forms of arsenic, which are bound to oxygen, chlorine or sulfur, are therefore present in poultry manure. “This waste is then spread on fields near poultry farms,†writes Ellen Silbergeld, a professor of environmental health sciences at Johns Hopkins University, in an e-mail. “The poultry industry is processing and selling poultry waste as garden fertilizer for consumers to use in home gardens and lawns.†According to chemist John Garbarino, a co-author of the study in Environmental Science & Technology, the arsenite present in manure and fertilizer binds poorly to soil particles, making it highly mobile in the environment such that it can easily contaminate nearby lakes and streams. Arsenite “is considered to be one of the more toxic arsenic species,†he writes in an e-mail. Roxarsone meets the FDA’s criteria for approval because it has been shown to be safe for chickens. The compound also meets the guidelines of the USDA, the agency that monitors food safety, because roxarsone residues in chicken tissue don’t exceed the agency’s safety levels. However, roxarsone’s potential downstream effects are not being addressed by either agency. And the agency responsible for regulating roxarsone’s byproducts in drinking water—the EPA— has no jurisdiction over roxarsone’s use in chicken feed. Richard Lobb, director of communications for the National Chicken Council—a non-profit organization representing poultry producers and distributors— argues that toxic forms of arsenic occur naturally in the environment and that the additional levels from the use of arsenic in poultry feed “are just so small†that they are most likely not a problem. “Arsenic is just there, it is elemental, it is in the rock in many, many areas and it just occurs naturally,†he says. The amount of arsenic released into the environment via poultry manure is approximately 250 to 350 metric tons per year, according to several recent peer-reviewed studies. This can be compared to natural releases of arsenic, mostly from volcanoes, which the EPA estimates are in the range of 2,800 to 8,000 metric tons per year. There are also other ways that arsenic gets into the environment, including metal smelting and coal burning, but the exact amount released from these other sources is unclear. How much of the “extra†arsenic entering the environment via feed is contaminating drinking water? No one seems to know for sure. “We do not know enough about this,†writes Silbergeld in an e-mail. “In some parts of the U.S., naturally occurring sources of arsenic [like those found in rocks] are a very important source of arsenic in ground water. In other areas, disposal of poultry waste may be the most important.†According to Brian Fairchild, a poultry scientist at the University of Georgia, the best way to clearly determine roxarsone’s downstream effects is to improve the technology used in the research. While some studies have been published on roxarsone’s effects on soil, “there’s no consistent data,†he says. If the scientists studying it today “are using the same old techniques that have been used for the past 10 years, I don’t think we’re going to get any closer to the answer than we were five years ago.†Lobb agrees that more—and better—studies would be helpful. “I think this area really cries out for some more objective research, and I hope somebody will supply that one of these days,†he says. “But the reason that no one is doing it, I guess, is because there does not seem to be a problem here.†In addition to potentially contaminating drinking water, some of the arsenic ingested by a chicken remains in its liver and muscle tissue—and is later eaten by consumers. A study led by Wallinga at the IATP, which was not reviewed by independent experts, found that of 155 chicken products bought from Minnesota and California supermarkets in 2004 and 2005, more than half contained detectable levels of arsenic. An earlier study by the USDA found that on average, people eat from 1.4 to 5.24 micrograms of inorganic arsenic each day from chicken alone. That amount again exceeds the EPA’s recommended daily levels for arsenic exposure. In order to have a lifetime cancer risk of less than one in 100,000, a person of average weight would need to ingest less than 0.469 micrograms of arsenic per day. Exposure to arsenic from eating chicken alone therefore is between three and 11 times the recommended safety level. The USDA, however, has set its limits much higher, and the amount of arsenic in the chicken tested by the IATP does not exceed them. The USDA’s limit for arsenic in poultry breasts is 500 ppb; the highest level of arsenic found by the IATP study was 21.2 ppb in some Purdue boneless breasts. But the USDA does not regularly test chicken breasts, thighs or legs to ensure that they conform to these standards. It only tests chicken livers because arsenic is known to concentrate there. Levels of arsenic also seem to vary consistently across chicken suppliers, so consumers can control the amount of arsenic they get from their chicken, at least to some degree. For instance, the IATP’s study found that Tyson chicken consistently tested low for arsenic, whereas Purdue was consistently at the high end. Organic chicken, which according to organic farming statutes cannot be fed roxarsone, also had low arsenic levels. Lobb, from the National Chicken Council, argues that the IATP’s study had serious flaws because it did not control for the other ways in which the chickens could have been exposed to arsenic. “The water supply for the chicken house is typically well water,†he says. “So if you happen to have arsenic-containing rock that underlies the chicken production area, then they’re going to be getting it just through their water.†Wallinga agrees that the study wasn’t designed as well as it could have been. He also wishes he could have tested more samples. But “It shouldn’t be up to Dr. David Wallinga to be monitoring the U.S. food supply for arsenic,†he says. “It should be up to the FDA. And if they’re not looking, they can’t answer these questions.†These days, Gwen Cox is no longer contract farming for Pilgrim’s Pride—and she’s much happier for it. She still raises a dozen “pet†chickens and about two dozen cattle, but she insists on doing so without roxarsone. She has had no coccidia outbreaks, though she admits that backyard flocks like her own are much less susceptible to disease than contracted poultry raised in close quarters. “When a bird can do as it wants, eat what it wants and have plenty of clean, fresh air as well as pure water and untainted feed, you’d be surprised how healthy and disease-free they remain,†she says. Cox and her friend Katherine Ecker, who owns Legacy Manor, a free-range farm in Boonsboro, Maryland, blame coccidia outbreaks partially on stress and lack of space. “Chickens in the broiler houses by nature have a tendency to pick at the ground,†Ecker explains. In contract farms, the chickens are in very close quarters, and since coccidia are spread by manure, the chickens have a much higher chance of getting sick. Ecker admits that she does occasionally have a coccidia outbreak, but when it occurs, she never uses roxarsone. She finds that amprolium, a compound that is significantly less toxic to humans, works as a comparable alternative. The pharmaceutical company Schering-Plough has also recently developed several coccidia vaccines for chicks; Embrex, another company, has a new in ovo coccidia vaccine that is injected into the egg before the chick hatches. These vaccines may prevent coccidiosis from occurring in the first place. With low-risk treatments readily available, why is roxarsone being used—and why is it still legal? Silbergeld of Johns Hopkins blames the FDA’s apparent reluctance to ban roxarsone on the influence of industry. “The major ‘ pressure’ to keep drugs in animal feeds comes from the pharmaceutical industry, since over 60 percent of antibiotic production, and 100 percent of roxarsone production, is used for nonclinical ‘growth promoting’ purposes in animals,†she writes in an e-mail. Wallinga points more of the blame directly at the regulatory agencies. They have not looked into the issue sufficiently, he says, so they have no reason to believe there is a problem. Agency spokesperson Herndon, however, contends that the FDA is “continuing to track the environmental monitoring data being generated by EPA, United States Geological Service and others.†But because farmers like Cox and Ecker—not to mention all European growers— successfully raise poultry without roxarsone, Wallinga sees no rational reason for the practice to continue until agencies can be sure that the practice is safe. “Clearly it’s possible to produce chicken with no or little arsenic,†he says. “So why are all these other people still using it?†(http://www.papercut.biz/emailStripper.htm) (http://www.papercut.biz/emailStripper.htm) Quote Link to comment Share on other sites More sharing options...
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