yellow and orange background pattern

Down on the Farm

By Jackie Powder

Agriculture, as it is practiced today in the United States, constitutes one of the biggest threats to the nation's water quality and quantity.

Over the past two decades, Concentrated Animal Feeding Operations (CAFOs), or "factory farms," have replaced the traditional family farm as the dominant agricultural model in the U.S. This industrialized brand of farming sends excessive amounts of animal waste, pesticides and bacteria into ground and surface waters. According to the Environmental Protection Agency, agricultural operations have polluted more than 170,000 miles of rivers across the country.

In addition to animal production on a massive scale, the operations also grow vast quantities of corn and soybean for feed, overpumping aquifers in the process.

Last year members of Kellogg Schwab's lab spent time at a swine CAFO in central Maryland to examine the operation's potential effects on nearby surface water and groundwater. Together, the two swine houses there hold 5,000 hogs, whose waste is stored in 12-foot-deep concrete manure pits beneath each structure. When the pits are filled to capacity, the untreated waste is siphoned off and spread on crop fields.

According to the U.S. Department of Agriculture, factory farms that house more than 55,000 pigs accounted for more than half of the total U.S. swine inventory. "[U.S.] regulations are not in place for the tremendous amount of waste generated in these very localized environments," says Schwab.

At the Maryland CAFO, he and his colleagues were specifically interested in analyzing levels of antibiotic-resistant bacteria that may have entered nearby surface and groundwater. CAFO-raised animals are typically given antibiotics intended for human use to speed their growth, a practice that fuels the development of drug-resistant bacteria. An estimated 10.3 million pounds of antibiotics are used annually in the U.S. to promote the growth of pigs.

Schwab recalled the conditions at the swine houses as deplorable. The animals live on slatted wood floors, surrounded by their own waste, until they're taken to slaughter.

Between 2002 and 2004, researchers, including students Amy Sapkota and Kristen Gibson, collected surface water and groundwater samples, both uphill and downhill from the swine facility. They found elevated levels of bacteria resistant to the antibiotics erythromycin, tetracycline and clindamycin in both the surface and groundwater down-gradient samples. In addition, the water collected downhill from the swine facility contained fecal indicators that were 4 to 33 times higher than the uphill water samples and well in excess of federal standards. The study appeared in the July 2007 issue of Environmental Health Perspectives.

The findings did not surprise Schwab. "You put that many pigs together with no waste treatment, and it's not unexpected that pollutants are going to saturate into the environment," he says.

His hope is that the mounting data on the health effects of industrialized farming will lead to stronger regulatory oversight of such operations and to increased enforcement of existing standards. "Many people don't know where our food comes from or how it's produced," Schwab said. "And one of the consequences is the amount of untreated waste that can leak into our groundwater."