Growing so large that they are now called factory farms, livestock feedlots are poorly regulated, pose health and ecological dangers and are responsible for deteriorating quality of life in America's and Europe's farm regions, according to a series of scientific studies published this week.
Feedlots are contaminating water supplies with pathogens and chemicals, and polluting the air with foul-smelling compounds that can cause respiratory problems, but the health of their neighbors goes largely unmonitored, the reports concluded.
The international teams of environmental scientists also warned that the livestock operations were contributing to the rise of antibiotic-resistant germs, and that the proximity of poultry to hogs could hasten the spread of avian flu to humans.
Feedlots are operations in which hundreds -- often thousands -- of cattle, hogs or poultry are confined, often in very close quarters. About 15,500 medium to large livestock feedlots operate in the United States in what is an approximately $80-billion-a-year industry.
Although the reports focused largely on Iowa and North Carolina hog and poultry operations, California has more than 2,000 facilities with at least 300 livestock animals each, half of them with more than 1,000, according to a 2002 estimate by the U.S. Environmental Protection Agency. Dairies, most of them in the San Joaquin Valley, dominate the industry in California.
Led by Peter Thorne, director of the University of Iowa's Environmental Health Sciences Research Center, the researchers outlined the need for more stringent regulations and surveillance of water and air near feedlots.
"There was general agreement among all [the scientists] that the industrialization of livestock production over the past three decades has not been accompanied by commensurate modernization of regulations to protect the health of the public or natural, public-trust resources, particularly in the U.S.," wrote Thorne, a professor of toxicology and environmental engineering.
The findings were from a consensus of experts from the United States, Canada and northern Europe who convened in Iowa two years ago for a workshop funded by the federal government to address environmental and health issues related to large livestock operations. Six reports, written by three dozen scientists mostly from the American Midwest and Scandinavia, were published this week in the online version of the scientific journal Environmental Health Perspectives.
Among their recommendations are limits on the population density of animals and mandatory extensive environmental reviews for new feedlots. They also recommended a ban on the use of antibiotics to promote animal growth, and that the drugs be available to farmers only through prescriptions.
In a new area of concern, the scientists said they were worried about the danger of a flu pandemic spread by feedlots with both hogs and poultry, and recommended new regulations to set minimum distances between the two.
Farm industry representatives said they were not familiar with the new reports and could not address specific findings or recommendations. But they said that many environmental improvements had already been made, and that some experts at universities had said the health risks were minor.
"The livestock industry has been under very intense scrutiny over the past 10 years, and as a result, has gone to great lengths and very high expense to try to improve their environmental record, across the board," said Don Parrish, the American Farm Bureau Federation's senior director of regulatory relations.
"We've definitely improved our game over the past 10 years," Parrish said, and most livestock owners "are being very sensitive to their neighbors and doing the best job they can."
Many of the risks come from the sheer volume of manure. Livestock excrete 13 times more waste than humans -- 133 million tons per year in the United States -- and some individual feedlots produce as much waste as entire cities.
The American Farm Bureau Federation maintains that almost every state regulates the amount of manure applied to the land to protect water supplies.
But the new reports criticized the current techniques.
"Generally accepted livestock waste management practices do not adequately or effectively protect water resources from contamination with excessive nutrients, microbial pathogens and pharmaceuticals present in the waste," the scientists reported.
The number of large livestock operations has surged in the last two decades, and farms with more than 500 hogs now account for three-quarters of the U.S. inventory. In Iowa, the average number of hogs per farm increased from 250 to 1,430 between 1980 and 2000.
California has more than 2,000 dairies, mostly in Tulare and Merced counties, and many have thousands of cows each. But the health risks to the dairy workers and their neighbors have gone unstudied, said Frank Mitloehner, director of the UC Davis Agricultural Air Emissions Center, who was not involved in the new reports.
UC Davis is launching a five-year study, led by Mitloehner, at dairies in Tulare and Merced counties, to examine the threat from air pollutants. Among the air pollutants from feedlots are ammonia; fine particles of manure, feed, soil and bacteria that can lodge in lungs; and endotoxin, which can inflame respiratory tissues and trigger asthma, bronchitis and allergies.
"There is potential for health effects, but in order to find out the intensity of them, we need to conduct these studies," Mitloehner said.
One of the new reports says a serious impact of feedlots "is their disruption of quality of life for neighboring residents," mostly in low-income and nonwhite communities.
"More than an unpleasant odor, the smell can have dramatic consequences for rural communities whose lives are rooted in enjoying the outdoors," says the report, compiled by researchers in Iowa, Illinois and North Carolina. "The highly cherished values of freedom and independence associated with life oriented toward the outdoors gives way to feelings of violation and infringement.... Homes become a barrier against the outdoors that must be escaped."
In water supplies, the biggest problems are nitrates and fecal bacteria, although experts have also recently discovered animal antibiotics and other drugs in waterways. The scientists recommended that private wells, which largely are unregulated, be monitored carefully near the factory farms.
The EPA was sued in 1989 by an environmental group, the Natural Resources Defense Council, for failing to regulate feedlots under the Clean Water Act. Fewer than 40% have permits for discharging pollutants because of EPA exemptions and lax federal and state enforcement, according to a 2003 report by what was then the General Accounting Office.
In June, the Bush administration proposed new regulations that would require feedlots to develop plans for controlling manure and obtain Clean Water Act permits.