Industrial animal food production heightens the risk of the spread of food-borne illnesses that afflict millions of Americans each year. Rates of heart disease, cancer, diabetes, and obesity—often related to excessive meat and dairy consumption—are at an all-time high. Respiratory diseases and outbreaks of illnesses are increasingly common among CAFO and slaughterhouse workers and spill over into neighboring communities and the public at large.

The Centers for Disease Control and Prevention (CDC) estimate that contaminated meat- and poultry-related infections make up to 3 million people sick each year, killing at least 1,000—figures that are probably underreported.1 Crammed into tight confinement areas in massive numbers, factory farm animals often become caked with their own feces. Animal waste is the primary source of infectious bacteria such as E. coli and Salmonella, which affect human populations through contaminated food and water.2 Grain-intensive diets can also increase the bacterial and viral loads in confined animal wastes. As a result, CAFOs can become breeding grounds for diseases and pathogens.

Dietary Impacts Americans consume more meat and poultry per capita today than ever before, part of a diet that is high in calories and rich in saturated fats. According to the Center for a Livable Future at Johns Hopkins University, meat and dairy foods contribute all of the cholesterol and are the primary source of saturated fat in the typical American diet.3 Approximately two-thirds of Americansare overweight or obese, increasing their chances of developing breast, colon, pancreas, kidney, and other cancers. Obesity and high blood cholesterol levels are among the leading risk factors for heart disease. Both of these conditions are associated with heavy meat consumption. More directly, researchers have linked diets that include significant amounts of animal fat to an increased incidence of cardiovascular disease.

On the other hand, studies regularly show that vegetarians exhibit the lowest incidence of heart problems.4 High intakes of fruits, vegetables, whole grains and Mediterranean dietary patterns (rich in plant-based foods and unsaturated fats) have been shown to reduce the incidence of chronic diseases and associated risk factors, including body mass index and obesity.5

Contaminated Feed Animal feeding practices also raise important health concerns. Corn and soybeans, for example, have been shown to absorb dioxins, PCBs, and other potential human carcinogens through air pollution. Once fed to animals, these persistent compounds can be stored in animal fat reserves. These harmful pollutants can later move up the food chain when animal fats left over from slaughter are rendered and used again for animal feed. As fats are recycled in the animal feeding system, the result is a higher concentration of dioxins and PCBs in the animal fats consumed by people. Animal and plant fats, both of which can store dioxins and PCBs, can compose up to 8 percent of animal feed rations.6

Worker Health CAFO workers suffer from numerous medical conditions, including repetitive motion injuries and respiratory illness associated with poor air quality. Studies indicate that at least 25 percent of CAFO workers experience respiratory diseases such as chronic bronchitis and occupational asthma.7 Slaughterhouse workers are also at risk for work-related health conditions. In early 2008, for example, an unknown neurological illness began afflicting employees at a factory run by Quality Pork Processors in Minnesota, which slaughters 1,900 pigs a day. The diseased workers suffered burning sensations and numbness as well as weakness in the arms and legs. All the victims worked at or near the “head table,” using compressed air to dislodge pigs’ brains from their skulls. Inhalation of microscopic pieces of pig brain is suspected to have caused the illness.8 After a CDC investigation, this practice was discontinued.

Community Health CAFOs can put neighboring communities at risk of exposure to dangerous air and water contaminants. More than a million Americans, for example, take drinking water from groundwater contaminated by nitrogen-containing pollutants, mostly derived from agricultural fertilizers and animal waste applications.9 Several studies have linked nitrates in the drinking water to birth defects, disruption of thyroid function, and various types of cancers.10 Further, the use of antibiotics on livestock over sustained periods is widely acknowledged to increase the prevalence of antibiotic-resistant bacteria. Infections from these new “superbugs” are difficult to treat and increase human risk of disease.11

In a study of 226 North Carolina schools, children living within three miles of factory farms had significantly higher asthma rates and more asthma-related emergency room visits than children living more than three miles away.12 A separate study found that people living close to intensive swine operations suffer more negative mood states (e.g., tension, depression, anger, reduced vigor, fatigue, and confusion) than control groups.13 Exposure to hydrogen sulfide—given off by concentrated animal feeding operations—has been linked to neuropsychiatric abnormalities.14

Food production that is safe for the environment, humane to animals, and sound for workers and communities gives us the best chance for a food system that is safe and healthy for eaters and producers alike.

1. P. Frenzen, A. Majchrowicz, B. Buzby, B. Imhoff, and the FoodNet Working Group, “Consumer Acceptance of Irradiated Meat and Poultry Products,” Agriculture Information Bulletin 757 (2000): 1–8.
2. Pew Commission on Industrial Farm Animal Production, Putting Meat on the Table: Industrial Farm Animal Production in America (Washington, DC: Pew Charitable Trusts and Johns Hopkins Bloomberg School of Public Health, 2008), 13.
3. Polly Walker, Pamela Rhubart-Berg, Shawn McKenzie, Kristin Kelling, and Robert S. Lawrence, “Public Health Implications of Meat Production and Consumption,” Public Health and Nutrition 8, no. 4 (2005): 348–56.
4. “Is Meat the Real Culprit in Heart Disease?” Doctor’s Guide, November 19, 1997.
5. Walker et al., “Public Health Implications of Meat Production and Consumption.”
6. Amy R. Sapkota, Lisa Y. Lefferts, Shawn McKenzie, and Polly Walker, “What Do We Feed to Food-Production Animals? A Review of Animal Feed Ingredients and Their Potential Impacts on Human Health,” Environmental Health Perspectives 115, no. 5 (2007): 663–70.
7. Doug Gurian-Sherman, CAFOs Uncovered: The Untold Costs of Confined Animal Feeding Operations (Cambridge, MA: Union of Concerned Scientists, April 2008), 60.
8. David Brown, “Inhaling Pig Brains May Be Cause of New Illness,” Washington Post, February 4, 2008; Centers for Disease Control and Prevention, “Investigation of Progressive Inflammatory Neuropathy Among Swine Slaughterhouse Workers: Minnesota, 2007–2008,” MMWR, January 31, 2008, 1–3.
9. Pew Commission, Putting Meat on the Table, 29.
10. Food and Water Watch, Turning Farms into Factories: How the Concentration of Animal Agriculture Threatens Human Health, the Environment, and Rural Communities (Washington, DC: Food and Water Watch, 2007), 7.
11. Gurian-Sherman, CAFOs Uncovered, 60.
12. Pew Commission, Putting Meat on the Table, 17.
13. Susan S. Schiffman and C. M. Williams, “Science of Odor as a Potential Health Issue,” Journal of Environmental Quality 34 (2005): 129–138.
14. Pew Commission, Putting Meat on the Table, 17.