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Other Meat Concerns: Antibiotics, Hormones and Toxins
Antibiotics
In the unsanitary conditions typical of confined feedlots used to fatten livestock, animals are routinely given continual low doses of antibiotics in feed to prevent sickness, promote faster growth and boost profits. The sheer volume of antibiotics being used may pose serious risks to public and environmental health, primarily because it may contribute to antibiotic resistance in pathogens that cause illness in people (Chee-Sanford 2009, Shea 2004).
Antibiotics used this way get into the environment via soil and water, often from animal waste that is either stored or spread on fields. Once in the water, these drugs can get into people (Chee-Sanford 2009). A 2007 study by scientists at the University of Illinois found that genes that conferred resistance to the widely used antibiotic tetracycline had transferred from bacteria in waste pools of hog manure into the bacteria in nearby water wells (Koike 2007). Groundwater is an important source of public drinking water. Lead researcher Dr. Roderick Mackie commented, “At this stage, we’re not really concerned about who’s got these genes. If the genes are there, potentially they can get into the right organism at the right time and confer resistance to an antibiotic that’s being used to treat disease” (University of Illinois 2007).
According to an analysis of U.S. Food and Drug Administration data by the Johns Hopkins University’s Center for a Livable Future, 80 percent of the antibiotics sold in 2009 were for use on livestock and poultry, and only 20 percent was for human medical use (Center for a Livable Future 2010). In 2010, the FDA said in a non-enforceable “guidance” that because “antimicrobial drug use contributes to the emergence of drug-resistant organisms, these important drugs must be used judiciously in both animal and human medicine.” It urged strict limits on antibiotic use in livestock (FDA 2010).
The FDA has tried for decades to restrict the use of antibiotics for non-therapeutic uses but has been stymied repeatedly by Congress (Harris 2010). At a 2010 press conference, former Principal Deputy Commissioner Joshua M. Sharfstein said the FDA believes “this is a public health issue of some urgency” (Harris 2010).
Hormones
Residues of artificial hormones that are widely used to promote growth in beef cattle, dairy cows and sheep may also increase the risk of cancer in humans and lead to higher rates of infection in animals. Many studies have found increased risk of breast, prostate and colorectal cancer associated with higher levels of insulin-like growth factor-1 (IGF-1) in blood and serum (Yu 2000, Hansen 1997). Recombinant bovine somatotropin (rBST), also known as rBGH, causes a significant increase in IGF-1 levels in milk from treated cows (Hansen 1997). Further, rBST-treated cows suffer higher rates and more severe cases of udder tissue inflammation and infection (mastitis), which requires increased use of antibiotics (Craven 1991, Pell 1992, FDA 1993, Monsanto 1993, Kronfeld 1997).
Using hormones this way is banned in most European countries and in Australia, Japan, and New Zealand and is not permitted in U.S. pork or poultry products, but it is common in U.S. beef cattle, dairy cows and sheep (Clancey 2006, USDA 2011).
More than a decade ago, scientists in Europe raised serious concerns about a wide range of potential health effects related to hormone use in livestock, particularly in the U.S. In 1999, the European Union’s Scientific Committee for Veterinary Measures Relating to Public Health said in a press release that six commonly used growth hormones had the potential to cause “endocrine, developmental, immunological, neurobiological, immunotoxic, genotoxic and carcinogenic effects,” adding that “even exposure to small levels of residues in meat and meat products carries risks, and no threshold levels can be established for any of the six substances” (EU 1999). The EU subsequently banned imports of U.S. beef because of scientific concerns about hormones, but the U.S government successfully challenged the ban in the World Trade Organization.
Toxins
- U.S. Food and Drug Administration
A number of widespread environmental toxins build up in animal tissues and are found in meat, sometimes at high levels. According to the FDA, “studies suggest that exposure to dioxin-like compounds (DLCs) may lead to a variety of adverse health effects, including reproductive and developmental problems, cardiovascular disease, increased diabetes and increased cancer. Because DLCs tend to accumulate in the fat of food-producing animals, consumption of animal-derived foods (e.g., meat, poultry, eggs, fish and dairy products) is considered to be the major route of human exposure to low levels of DLCs.” (FDA 2004a) According to the FDA, most human exposure to dioxins comes from food, with 95 percent of that coming from animal fats (FDA 2004a).
Among fish, tuna and farmed salmon are of particular concern. A 2004 analysis of two metric tons of farmed and wild salmon purchased from stores around the world showed consistently and significantly higher concentrations of PCBs, dioxins, and the widely banned insecticides toxaphene and dieldrin in farmed salmon (Hites 2004). EWG’s tests of farmed salmon from U.S. stores support this finding. On average, the farmed salmon had 16 times the dioxin-like PCBs found in wild salmon, four times the levels of beef, and 3.4 times the levels found in other seafood (EWG 2000). Mercury contamination of seafood is also a well-documented problem. According to the FDA, “Nearly all fish and shellfish contain traces of methyl mercury. However, larger fish that have lived longer have the highest levels of methyl mercury because they’ve had more time to accumulate it. These large fish (swordfish, shark, king mackerel and tilefish) pose the greatest risk” (FDA 2004b).
