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(CNN) -- In the wake of an outbreak that has left an estimated 1,300 people sick with salmonella infections, and the recall of more than half a billion eggs, a debate is brewing over whether modern farming methods pose a health risk.
According to the United Egg Producers, about 95 percent of all chickens are raised in an industrial setting. These chickens are confined in small cages, in closely monitored conditions -- many with more than 100,000 birds at a single location.
Are free-roaming chickens less prone to salmonella? Is organic safer than inorganic? Did the strain that caused the recent outbreak arise because of factory farms?
CNN sought out sources from a variety of key players in this debate. Not surprisingly, they have different perspectives on these issues. Here is a sampling:
The Food Safety and Inspection Service, part of the U.S. Department of Agriculture, is responsible for the safety of meat, poultry and eggs. On the FAQ section of its website, the agency asks: "Are chickens labeled 'Kosher,' 'free-range,' 'organic,' or 'natural' lower in Salmonella bacteria?":
The agency does not know of any valid scientific information that shows that any specific type of chicken has more or less salmonella bacteria than other poultry.
The Humane Society of the United States lobbies to ban many conventional farming methods, such as keeping many chickens together in small cages. On its website, the society lists studies showing a higher prevalence of salmonella at operations where chickens are tightly caged:
One reason millions of salmonella-infected eggs reach American supermarkets every year is the mistreatment of hens by the egg industry. Cramming 100,000 birds or more under a single roof in tiny battery cages creates an immense volume of contaminated airborne fecal dust that can rapidly spread salmonella infection between the birds.
Author Michael Pollan says he believes our health and the environment would be improved by a return to less industrial methods of food production. He is the author of several books, including "The Omnivore's Dilemma," "In Defense of Food" and "Food Rules." He told CNN's Dr. Sanjay Gupta that he doesn't know if organic eggs are safer -- but he buys them anyway:
There have not been the same sort of outbreaks with organic operations. However, organic egg operations are so tiny compared to conventional egg producers, that doesn't necessarily mean anything. I eat eggs, and I buy them whenever I can at the farmers' market. I know how those eggs are raised. They're raised on grass. The animals live outdoors, in small flocks. They're raised much the same as in the days before we had to worry about salmonella.
Eric Schlosser, author of "Fast Food Nation," is a critic of large farming operations and supports stricter government regulation:
Small farms aren't necessarily going to be perfect, but keep in mind if you have a salmonella problem at small farms, people in a relatively small area [are] going to get sick. Whereas if you have a salmonella problem like the one we have now, you can have tens of thousands of people getting sick. Salmonella was not a problem in the United States until the early 1980s, when these mega-producers formed.
Michael Lacy heads the University of Georgia Department of Poultry Science, a major center of research on agriculture:
I know of no research that shows large-scale egg farming is less safe than any other. There is no scientific evidence that free-range or organic eggs are less prone to S. Enteritidis [the strain in the current outbreak]. Most poultry scientists and poultry veterinarians would say that biosecurity on large farms would reduce the chances of birds being exposed to S. Enteritidis compared to backyard farms, where birds face exposure from multiple sources. Salmonella has been around for eons. I do think it is important to state that eggs are safe to eat if they are cooked properly.
Andy Schneider of Alpharetta, Georgia, is known as "The Chicken Whisperer." He has a radio show where he doles out advice on raising chickens, and organizes a meetup group, with more than 1,100 members, for chicken-raising fans in and around Atlanta:
You need to realize, that just because they're in the backyard, they're not exempt from getting the same illnesses as commercial birds. ... There's no scientific data at all, no studies, to make a claim that backyard birds are healthier, or eggs are better [with regard to salmonella]. There are some studies that talk about nutrition, or saying they are more nutritious: lower in cholesterol, higher omega-3s."
Dr. Christopher Braden is acting director of the Centers for Disease Control and Prevention's Division of Foodborne, Waterborne and Environmental Diseases. He says salmonella was identified more than a century ago, by Dr. Elmer Salmon, and has long been viewed as a threat by public health officials:
Surveillance for salmonella has been conducted since the early 1900s. S. Enteritidis has been a well-known serotype for a long time, but it was not until the 1980s that it was identified as a serotype that could contaminate eggs by transmission through hen ovaries.
Michelle Jay-Russell is a scientist at Western Institute for Food Safety and Security, University of California, Davis. She points out this article, laying out a theory for how S. Enteritidis may have developed in the 1970s. Like the bacteria, she says our understanding of them is still evolving:
Salmonella as a group of bacteria are probably thousands of years old, based on evolutionary studies. But there is continuous evolution that changes the makeup of the "genus," creating new emerging strains such as the egg-associated salmonella enteritidis serotype. The recognition of salmonella as a pathogen didn't occur until we developed the laboratory tests to detect it. So while people have probably been getting sick from salmonellas for a very long time, we only realized these illnesses were due to salmonella after having diagnostic tests to find salmonella in human stools, or blood cultures in severe illnesses.