The Meat Myth: Free-Range Isn't Always Safer

Factory-farmed pork is hardly an ideal food—but pigs from small farms might be more likely to make you sick

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In previous Atlantic posts I've worked hard to explain the underlying reasons for my disdain of animal agriculture. Those who've engaged my arguments will know my position well enough: I fundamentally oppose raising animals for food that humans don't need. This claim holds true regardless of how the meat is produced or consumed.

I mention this point because the study I'm about to highlight could easily be distorted. The report, published in the February 2011 issue of Foodborne Pathogens and Disease, challenges the perception that intensive animal farming is more likely to spread foodborne pathogens than free-range systems. My choice in drawing attention to this counterintuitive article is decidedly not to argue that factory farms are okay and that we should all go out and support Tyson's. To the contrary, I want to advance the more radical notion that animal farming in general—whether confined or free-range—is fraught with unique problems that we could easily avoid by not eating meat.

These claims will surely strike food purists as heresy. But Davies's evidence is compelling.

Two other caveats before I summarize the article. First, although this study took place without corporate funding, the author—Dr. Peter Davies—has accepted support from the pork industry in the past. Whether or not past support skews future research remains an open question, but it's important to note that the study was published in a peer-reviewed, world-class journal and is based on scores of other studies that found similar results. And second, I'm well aware that the main concern that jumps to mind when it comes to factory farming is often how low-grade antibiotics use leads to potentially deadly, antibiotic-resistant pathogens. This is undoubtedly a huge problem. But this study addresses only foodborne diseases, and thus so does my analysis. This focus is not meant to dismiss or downplay the pressing problem of antibiotic resistance.

The study in question is an exhaustive analysis of existing evidence on the connection between intensively managed pig farming and foodborne parasites. The article caught my eye because Davies, of the University of Minnesota, attempts something uncharacteristic for an article published in a professional scientific journal. He begins by chiding the mainstream media for its selective reporting on this controversial topic. And not very gently.

"Misinformation in public discourse," Davies writes, "has achieved pandemic potential with the rise of blogging and other social networking tools." Discussions of food and agriculture, he continues "are mostly ideological and heavily value laden." Scientists, he argues, must do more than practice sound science. They must exhort the "scientific community . . . to be more visibly engaged in refuting misinformation as well as presenting new information." What's needed is something sorely lacking in so much popular writing about animal agriculture. In essence, "factual accountability."

Lecture delivered, Davies drops his bomb: "Available evidence does not support the hypothesis that intensive pork production has increased risk for the major bacterial foodborne pathogens." Nor does it support the opinion "that pigs produced in alternative systems are at reduced risk of colonization with these organisms." In fact, Davies explains, "pigs raised in outdoor systems inherently confront higher risks of exposure to foodborne parasites."

These claims will surely strike food purists as heresy. But Davies's evidence is compelling. Take Trichinella spiralis. This is a nematode parasite that killed thousands of consumers a year in the late 19th century but is extremely rare today. Davies attributes this impressive multi-decade reduction to the improved management practices of modern swine production. Rodent control and regulated feeding practices, he explains, have "practically eliminated the risk of infection." If a comparison to the 19th century seems disingenuous, note that the 138 cases recorded by the Center for Disease Control between 1997 and 2006 represent a 95 percent decrease in annual infections since the 1940s, and a 76 percent decrease since the 1980s.

During this 10-year span (1997-2006), there were only 15 recorded cases of T. spiralis, nine of which came from commercial pork operations. The other six were linked to "home-raised or direct-from-farm swine." Given that commercial swine facilities produce 100 times more pigs than free-range systems, these numbers suggest that, on a pig-by-pig basis, there's "an 80-fold greater risk (per pig produced) of trichina infections resulting from eating niche market versus commercial pork products." I suppose there are a million ways to quibble with these numbers, but they nonetheless seem consistent with Davies's larger claim that "it is inevitable that pigs with outdoor access will be at greater risk of Trichinella infection due to exposure to wildlife reservoirs."

A far more common parasite that Davies addresses is Toxoplasma gondii. It's likely that a third of us have been laid low by this nasty protozoan, one that accounts for about 75 percent of all foodborne illnesses in the United States. Pork presents the greatest risk of exposure among commercial meats. A 1983-84 national assessment "found that 23% of market hogs and 42% of sows were seropositive for Toxoplasma." As for the actual presence of Toxoplasma in pork, a 1960s study found a 32 percent rate of infection in pork loins. These are bad numbers by any measure.

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James McWilliams is an associate professor of history at Texas State University, San Marcos, and author of Just Food: Where Locavores Get It Wrong and How We Can Truly Eat Responsibly.

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