Another Something Foul in the Air above Hog Farms

Story by Cory Hatch, Photos by Rick Dove

Researchers find antibiotic resistant bugs floating in dust particles above hog farms

Outside Karen Priest’s home, tucked away in the North Carolina countryside, the Dominos delivery boy always looks a little green. Thirteen thousand hogs live nearby. When Priest pays for the pizza, she feels compelled to apologize. “It’s just awful,” she says about the constant odor. “Some days it’s like a burning inside your nose.” Priest hasn’t opened her windows since 1994, when the hog farms moved in next door. Her son rarely plays sports in the yard.

In hog towns across the country, Priest’s story is common. These controversial large-scale factory farms (called concentrated animal feeding operations or CAFOs) keep anywhere from 5,000 to 600,000 hogs confined in tiny pens and pumped full of antibiotics. Their urine and feces fall through slots in the floor to waste lagoons below. There, the waste sits untreated or gets sprayed out onto fields, ostensibly as fertilizer. As the swine sewage dries, it breaks down into a witch’s brew of chemicals–hydrogen sulfides, ammonia, organic acids, phenols, and alcohols–that form dust clouds above the factories. This cocktail of airborne chemicals leaves an indelible stench on the breath of factory farm employees and the drapes of nearby homes.

While the odor of these farms has already mobilized dozens of communities to fight for cleaner air, recently, researchers have found a new reason for hog farm neighbors to hold their breath: the airborne dust above these farms harbors antibiotic-resistant bacteria. Although no researchers have successfully linked these airborne bacteria and human disease, they suspect the breathable bugs cause hundreds of respiratory illnesses each year; and doctors might have few options to treat them.

Farmers started the widespread use of antibiotics in animal feed in 1948. Since then, factory farms have increased their use of antibiotics to 50 million pounds a year, accounting for 40 percent of all the antibiotic use in the United States, according to Johns Hopkins researchers. Hog farm operations alone use 10.3 million pounds of antibiotics annually. In addition to the large doses that farmers give to animals to prevent infections, continuous low doses of the drugs promote faster growth in the animals.

Antibiotics don’t disappear when a hog digests its meal, but pour out in the 110 million tons of swine waste that US hog farms produce each year. Somewhere from the trough to waste lagoon, a few bacteria survive the antibiotic onslaught and reproduce to form a resistant strain.

For years, researches have suspected that this waste, and the antibiotic resistant bacteria that live there, contribute to the high frequency of respiratory illnesses in the factory farm workers and their neighbors. It wasn’t until 2002 that researchers glimpsed the first scientific evidence that antibiotic resistant bacteria can become airborne when USDA scientist named James Zahn found bacteria attached to dust particles at the farms. He attempted to publish the findings several times, but USDA officials refused to let him release the information. Zahn eventually quit USDA and still refuses to speak about the topic. But one of his colleagues, Alan Dispirito, an associate professor at Iowa State University who collaborated with Zahn on the research, says that 90 percent of the organisms attached to the dust particles they studied displayed antibiotic resistance. “We, initially, were working on ways to deal with the odor issue,” says Dispirito. “But when were looking at dust particles, we started to see that we could detect what antibiotics they were using.”

USDA officials maintain
that Zahn wasn’t qualified to talk about the bacteria. “ The ARS (Agricultural Research Service) instructed him not to discuss the public health ramifications of this because it wasn’t his field of expertise,” says Sean Adams, public affairs spokesperson for ARS-USDA.

New research from Johns Hopkins University corroborates Zahn’s discovery. The team, led by Amy Chapin of the Johns Hopkins Bloomberg School of Public Health, sampled the air in these factories. The device they used, called an “all glass impinger,” uses suction to draw air in through a glass tube that curves downward to mimic the nasal passages of a human. Researchers culture whatever microbes they collect. Chapin and her colleagues found antibiotic resistance in 98 percent of the bacteria isolated from the air of one factory hog farm, according to their paper in the February 2005 issue of Environmental Health Perspectives..

The danger to people, Chapin says, is that hog farmers use many antibiotics that are closely related to human drugs such as erythromycin, bacitracin, and tetracycline. If people who inhale the dust from these farms get a lung infection from these antibiotic resistant bacteria, conventional hospital antibiotics might not cure the disease. In some instances, such as erythromycin, hog farms and hospitals use the same drug, increasing the chance that hospital drugs won’t effectively treat a human infection. Furthermore, one hog farm drug, virginiamycin, is a close analogue to quinupristin-dalfopristin (QD), a combination of drugs that doctors use as a last resort to fight antibiotic resistant illnesses. If virginiamycin confers QD resistance to bacteria infecting a human patient as researchers suspect, doctors might not have another option.

While no current studies directly link these airborne antibiotic resistant bacteria to illness in humans, the circumstantial evidence is hard to ignore. In March 2000, University of North Carolina School of Public Health researcher Steve Wing authored a paper in which he outlined respiratory disease rates in rural neighborhoods within two miles of hog farms. He found the number of people who, over six months, reported 12 or more incidents of upper respiratory problems (runny nose, coughing, headaches, mucous membrane irritation, and sore throat) almost doubled near hog farms when compared to the control group. “It’s really bad,” says Wing. “Thirty to forty thousand head of livestock is like a city of 50,000 people without a waste treatment plant.” In another review, conducted in 2002, University of Iowa found very high rates of illness, especially respiratory illness, in factory hog farm hands. Nearly 70 percent of these farm employees complain of acute bronchitis and 25 percent complain of chronic (lasting two or more years) bronchitis. These diseases are just a small sample of ailments that also include asthma, depression, and fatigue. Wing says a complex mixture of pollutants such as hydrogen sulfide gas, dust, and live airborne viruses and bacteria cause these symptoms. “They [hog farmers] have lung problems,” says Paul Willis, a hog farmer who avoids the over-use of antibiotics at The Niman Farm, a free-range farm he runs in Iowa. “[Some] have had to stop, on their doctors orders, from raising pigs that way.”

Most farmers and pork officials say the use of antibiotics is necessary to prevent disease and keep the animals growing quickly. They claim that periodic high doses of antibiotics prevent disease in the herd, while continuous low doses knock out gut flora leading to better absorption of nutrients and fatter pigs. “I think they (antibiotics) are a very important management tool in all hog farm operations,” says Liz Wagstrom, a veterinarian and science and technology spokesperson for the National Pork Board. “In most cases, they need to be a part of that tool belt to make sure the animals are healthy, growing well and helping produce safe, quality pork.” Eliminating growth promoter antibiotics, Wagstrom says, would lower a hog farmer’s profit margin by four dollars and fifty cents a pig, a stiff price to pay when the average profit per pig only reached four dollars in the US over the last 10 years.

But in reality, continuous low doses of antibiotics and the resulting antibiotic resistant bacteria probably isn’t necessary or worth the potential repercussions. “It’s the chronic exposure [to antibiotics] that allows resistance to develop,” said Ewen Todd, a Michigan State University microbiologist. “I don’t think the benefit outweighs the cost.” Further, many operations such as the Niman Farm manage to make money without growth promoter antibiotics.

Though hog farm advocates say antibiotics help farmers survive, industry officials don’t necessarily oppose research that could address potential community health problems. In March of 2005, The National Pork Producers Council voiced its support of an EPA plan that limits liability for factory pork farmers in exchange for research access to the farms to study air quality issues. While the agreement may provide essential scientific information about the hazards these farms pose, they could also provide a loophole for farms that consistently break air quality standards. According to Rick Dove, an environmental activist in North Carolina, many hog farms already break the rules. He says that some farmers spray the waste directly into the wind to volatilize the waste before it hits the lagoons, a violation of air quality standards. “(Spraying waste as fertilizer) for growing crops is a pretext for getting rid of these wastes,” he says.

One more loophole, even if it means more research, is hardly consolation to people like Karen Priest who live with these hog farms. Her neighbors complain of respiratory and gastrointestinal disorders. Priest herself developed sinus infections, the latest of which her doctor treated with three different antibiotics before she got healthy. But until scientists prove that her noxious neighbors actually cause illness, Priest can only hunker down behind a bunker of potpourri, scented candles and air freshener… or move to a new home.

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