By Madeline Drexler (wrote the book: Secret Agents)
Madeline Drexler argues that farm animals in this country live in unmatched squalor. "The site of modern meat production," she writes in her book Secret Agents, "is akin to a walled medieval city, where waste is tossed out the window, sewage runs down the street, and feed and drinking water are routinely contaminated by fecal material." And these kinds of conditions lead to problems. One USDA study found that 50 percent of feedlot cattle carried the E. coli O157:H7 bacterium in their intestines during the summer months; another study found that 7 percent of chickens sampled at slaughterhouses had salmonella and 30 percent had campylobacter. Drexler is a former medical columnist for The Boston Globe and was a Knight Science Journalism Fellow at the Massachusetts Institute of Technology from 1996 to 1997. Here is her account of how contamination is pervasive in the meat industry.
An excerpt from Secret Agents: The Menace of Emerging Infections by Madeline Drexler, published by the Joseph Henry Press (2002). Reprinted by permission. To read the full text online, go to http://www.nap.edu/.
The E. coli O157:H7 saga shows how the denizens of an animal's GI tract find their way to our own digestive systems. This brings up a delicate point, rarely discussed in polite company, but one central to the rest of this chapter. Put simply, animal and human waste is the source of most foodborne illness. And what we eat usually becomes contaminated long before it reaches us -- during processing, at the slaughterhouse, or right on the farm.
Of course, that's a resonant theme in public health. The sanitary revolution of the nineteenth century -- the discovery that the diseases of squalor and overcrowding could be prevented with sewage removal and clean water -- was occasioned by fear of cholera, typhoid fever, and other pestilential diseases. Before this transformative event, daily life was unimaginably filthy. "Thousands of tons of midden filth filled the receptacles, scores of tons lay strewn about where the receptacles would receive no more," observed an English medical officer in Leeds in 1866. "Hundreds of people, long unable to use the privy because of the rising heap, were depositing on the floors."
Which is precisely how the animals that become our food live today. And why, at the CDC, officials in the foodborne and diarrheal disease branch long for a sanitary revolution: clean piped water and sewage disposal and treatment -- for animals. Like the nineteenth century innovations that controlled typhoid fever, animal sewage would be separated from the human food and water supply, and also from the animal food and water supply. "It's a paradigm shift," says the CDC's Fred Angulo. "Farmers don't consider themselves food handlers."
The site of modern meat production is akin to a walled medieval city, where waste is tossed out the window, sewage runs down the street, and feed and drinking water are routinely contaminated by fecal material. Each day, a feedlot steer deposits 50 pounds of manure, as the animals crowd atop dark mountains composed of their own feces. "Animals are living in medieval conditions and we're living in the twenty-first century," says Robert Tauxe, chief of the CDC's foodborne and diarrheal diseases branch. "Consumers have to be aware that even though they bought their food from a lovely modern deli bar or salad bar, it started out in the sixteen hundreds."
The feedlot is just the start of their fetid journey. At the head of the slaughterhouse line, a "knocker" wields a pistol-like device to drive a metal bolt into a steer's head. Other workers cut the animal's throat to drain blood, and use machines to sever the animal's limbs, tear off its hide, pull out its organs. More than 300 animals may pass through the line in an hour, each carcass weighing 650 to 800 pounds. At the slaughterhouse, writes journalist Eric Schlosser, "The hides are now removed by machine; but if a hide has not been adequately cleaned first, pieces of dirt and manure may fall from it onto the meat. Stomachs and intestines are still pulled out of cattle by hand; if the job is not performed carefully, the contents of the digestive system" -- i.e., waste -- "may spill everywhere."
A United States Department of Agriculture study published in 2000 found that 50 percent of feedlot cattle being fattened for slaughter during the summer months carried the E. coli O157:H7 bacterium in their intestines -- a far higher figure than previous government estimates. Another study found that about 43 percent of the skinned carcasses tested positive before being eviscerated, suggesting that microbes were being spewed within the plant.
In early July 2000, the Excel Corporation -- the nation's second largest beef processor -- allowed an Associated Press reporter to visit its huge Fort Morgan, Colorado, meat packing plant. Asked about the dangers of tainted meat reaching consumers, Excel's food safety director replied: "It's like a roll of the dice or a game of Russian roulette." Two weeks later, the face of three-year-old Brianna Kriefall, of South Milwaukee, appeared on front pages across the country. She had died from eating a slice of watermelon at a Sizzler restaurant. The watermelon had been sliced in the restaurant kitchen, on the same countertop where a meat grinder was used to convert steak trimmings -- E. coli-contaminated steak trimmings -- into hamburger. The trimmings came from sirloin meat packed in heavy vacuum-sealed bags. The bags had been shipped just a few days earlier from Excel's Fort Morgan plant.
Chicken farming is just as noxious. But before delving into that, a word about chickens: they're not all created equal. In the agribusiness world, there are two kinds of chickens -- the broilers that give us meat, and the layers that give us eggs -- and they are totally separate industries governed by different practices, riddled with different problems, and even centered in different parts of the country (the top broiler states are Georgia and Arkansas, while the top egg-producing locales are Ohio and California).
First, a look at broilers. In her book Spoiled, journalist Nicols Fox writes that "If chicken were tap water, the supply would be cut off." Oddly enough, the government doesn't have hard numbers on Salmonella and Campylobacter contamination rates, and what they do have is hardly appealing. A 1999 study from the USDA's Agricultural Research Service, for instance, found that 7 percent of chickens sampled at slaughterhouses had Salmonella and 30 percent had Campylobacter -- but, as one scientist there admitted, those numbers are probably low. For many years, researchers assumed that clearing feces, rodents, and insects from the broiler houses where the birds live out their five to nine weeks would solve the problem. But new studies suggest that the source of chicken contamination may be more deep-rooted. The 9.5 billion young broilers that Americans eat each year are actually the fourth generation in a carefully husbanded line. Scientists now believe it's the three previous generations -- the "breeders" -- that regularly pass down infection. When he tested birds at the top of the pyramid -- the great-grandparent breeder flocks -- microbiologist Nelson Cox at the USDA's Russell Research Center found that 36 percent were positive for Salmonella. Cox suspects that these birds transmit pathogens to subsequent generations by contaminating their own eggs with feces that carry high levels of Salmonella, Campylobacter, Listeria, and Clostridium perfringens. Because the hen's body temperature is quite warm -- between 104 and 107 degrees Fahrenheit -- she usually lays her egg on a day in which the air is cooler than her body. That temperature gap forces bacteria on the porous surface of the egg to get sucked into the membrane underneath, where most organisms live contentedly while the fertile egg is incubating. When the chick pecks its way out, it eats the pathogens. "The largest contributor to contamination of a broiler flock," says Cox, "is the mother hen -- the feces of the parent bird." That means the human disease on our end of the food chain won't end until farmers either clean up the three generations above, or scientists figure out how to snap the links of contamination. Vaccines may not be the answer, since they are only effective against diseases that make chickens sick -- and both Salmonella and Campylobacter are benign commensals, living happily in the birds' intestinal tracts without causing harm. Another possibility, slaughtering the priceless great-grandparent breeder birds, would drastically raise chicken prices.
Now on to layers. Modern houses for egg production are avian megalopolises. In 1945 the typical henhouse sheltered 500 birds; today it can contain 80,000 to 175,000, with up to 20 houses in a single operation. (As in the livestock industry, this huge scale is a result of industry consolidation; in 1996 there were approximately 900 egg operations in the United States, compared to 10,000 in 1975.) Laying flocks stay in the same house for up to a year and a half, which means that detritus builds up. "You have a lot of everything," says Richard Gast, a microbiologist at the USDA's Southeast Poultry Research Laboratory. "A lot of birds, a lot of manure, a lot of moisture, a lot of dust. Everything that walked into that house -- every two- and four- and six-legged creature -- is a potential vector for moving it around."
What spreads in this tenement is Salmonella enteritidis, or SE, the villain behind most egg-related outbreaks. SE is a versatile bug, capable of infecting birds through two different routes. One is orally, since chickens eat feces. Another route -- more troubling, because scientists haven't figured out how to interfere with it -- ascends through the cloaca, the cavity in birds into which empties the products of both the intestinal and reproductive organs. SE is sucked up into the bird's reproductive tract and eventually into the ovaries. From there, it gets inside eggs even before the shell is laid down -- indeed, most eggs become systemically contaminated with Salmonella enteritidis in this way. Just where SE came from, or why it spread so suddenly in the 1980s, remains a mystery. Found in 1 of every 20,000 eggs, SE makes French toast, Hollandaise sauce, and raw cookie dough risky culinary excursions.
Animal waste and its dangerous microbes aren't confined to the farm, of course. Manure -- spread through fertilizer, irrigation water, insecticide solutions, dust, even wild birds and amphibians -- gets on produce too. Typical is an outbreak that took place in 1998, when patrons of a Kentucky Fried Chicken restaurant in Indianapolis became ill with E. coli O157:H7. Zeroing in on KFC's cole slaw, investigators discovered that some of the cabbage came from fields supplying a Texas vegetable company -- and that, during a severe drought, the fields were flooded with untreated water from the Rio Grande, where cattle had waded and relieved themselves in the irrigation canals. Similarly, at Disney World in Orlando, Florida, thousands of visitors from all over the country were believed to have been infected with Salmonella in 1995 after drinking unpasteurized orange juice at special "character breakfasts" at the park, in which costumed Disney characters mingle with the guests. The orange juice came from a small processing plant nearby -- a plant where the walls and ceiling of the processing room had cracks and holes, and where frogs congregated near the equipment. Outside the plant, investigators found Salmonella in a toad, in tree frogs, in soil, and on unwashed oranges. E. coli O157:H7 contaminates unpasteurized cider when fallen apples touch cattle or deer waste and are then mixed with other pieces of fruit. Numerous lettuce outbreaks have occurred after the heads were exposed to cattle manure. Organic foods are hardly immune to these pitfalls. In fact, microbiologists have found more bacterial contamination on organic than on conventionally grown produce, and no one is quite sure how much composting it takes to knock off pathogens in manure. That gap in knowledge has real-life consequences. In rural Maine in 1992, a woman who abided by a lacto-vegetarian diet, consisting almost exclusively of vegetables fertilized with manure from her cow and calf, developed E. coli O157:H7 when she failed to wash the vegetables well enough. Through improper handwashing, she passed the infection on to three neighborhood children, one of whom, a three-year-old boy, died of kidney failure.
Farm conditions create a wide-open channel down which emerging pathogens travel from food animals and produce to people, and the modern food industry has converted a two-lane country road into a 12-lane interstate. "Salmonellosis is rare in developing countries, where sanitation is poor and diarrheal diseases are endemic, but where food production and consumption are local," writes Martin Blaser, chairman of the department of medicine at New York University, in the New England Journal of Medicine. Blaser's dispiriting conclusion? "Salmonellosis -- with the notable exception of typhoid fever -- is a disease of civilization. "
And outbreaks are not so much "point source" as pointillist. Changes in agriculture and food manufacture -- vaster and fewer farms, slaughter plants, and processing facilities -- have given pathogens a larger stage on which to strut. In this miraculous food economy of scale, when things go wrong, they go wrong in a big way. Mass-distributed items with spotty or low-level contamination are consumed by people living far from the source. This leads to a new, insidious kind of epidemic: one with low attack rates (less than 5 percent of the people who eat the contaminated food) but huge numbers of dispersed victims. Take the massive 1994 outbreak of Salmonella enteritidis. Usually, SE is linked to undercooked eggs or egg products. But Schwan's ice cream, made in Minnesota and delivered to homes in all 48 contiguous states, was made from premix that had been transported to the plant in tanker trailers -- trailers that had previously carried unpasteurized liquid eggs. Though the insides of the tankers were supposed to be washed and sanitized after hauling eggs, drivers sometimes skipped that laborious step. Across the country, an estimated 224,000 ice cream aficionados -- mostly kids -- paid the price in the largest outbreak of salrnonellosis ever recorded from a single food source.