A concentrated animal feeding operation, or CAFO, is exactly what it sounds like -- an industrial approach to livestock that concentrates hundreds, thousands, or tens of thousands of animals in pens where they are fed. In some cases, chickens, pigs, cows or other livestock can spend most of their lives in CAFOs.

While environmentalists and animal rights activists have cited numerous problems with CAFO facilities, ranchers and others maintain that CAFOs can be managed in a safe, environmentally sound manner while providing low-cost food to millions.

Regardless of who's right, the worldwide growth of CAFOs continues to be a political and legal controversy.

CAFO Facts and Figures

According to the EPA, there are over 15,000 CAFO operations in the United States; thousands more exist in other countries. The EPA definition of a CAFO is a confined area where feed is brought to the animals, rather than allowing the animals to graze in open pastureland or fields.

In addition to live animals, a CAFO can also contain the carcasses of dead animals, manure, urine and production equipment. CAFOs generally do not have any grass or other vegetation growing inside their confines.

The EPA -- which has regulatory authority over CAFOs -- has specific definitions for CAFOs that differentiate between smaller animal feeding operations, or AFOs, and large, medium and small CAFOs. The differences include what kinds of animals are being raised, how many animals there are, how manure is handled and where surface waters like creeks and ponds are located.

CAFOS are relatively new operations; before World War II, there were very few CAFO facilities anywhere.

But since the 1950s, chickens and other poultry started being raised in factory farm conditions, and cattle, swine, aquaculture and other CAFOs soon followed.

The rapid growth of CAFOs is nothing less than startling: According to researchers from the Johns Hopkins Bloomberg School of Public Health, 57 million pigs were distributed among one million American farms in 1966. But by 2001, these same 57 million pigs were raised on just 80,000 farms, and over half were raised on just 5,000 CAFO facilities.

CAFOs and the Environment

If you've ever been within a mile of a large CAFO, you probably knew it before you saw it -- the stench created by tons of raw manure is enough to knock a buzzard off a shitwagon.

Most manure and waste on CAFOs is handled by manure pits or piles (if it's handled at all). These can become very large very quickly due to the sheer volume of waste created: A pig, for example produce roughly four times the amount of waste each day that a person creates, so a CAFO with 8,000 pigs is comparable to a city of 32,000 people in terms of waste management.

Beyond the mind-boggling stench, there are significant public health and safety problems associated with manure and other wastes (feathers, hair, urine, carcasses of dead animals) on CAFOs. Ammonia, sulfur dioxide, methane, hydrogen sulfide, dust and other particulates from CAFOs harms the health of farm workers and people living downwind -- research has found that up to 30 percent of CAFO workers suffer from respiratory diseases including acute and chronic asthma.

In addition to air pollution, manure and waste on CAFO facilities has a serious impact on water quality. Though manure can sometimes be spread on nearby fields, it often exceeds the amount that can be absorbed by the fields' plants and soil, so that – plus the runoff from the CAFO itself -- can destroy water quality for miles downstream.

Surface water like lakes and streams, plus groundwater (which often forms an important drinking water supply in rural communities) can be permanently damaged when CAFOs introduce heavy metals such as arsenic, antibiotics, nitrogen, phosphorus, dust, mold, pathogenic bacteria and bacterial toxins into the water.

CAFO Management and Alternatives

The federal EPA and state authorities have regulatory jurisdiction over CAFO facilities, though the degree of oversight varies from time to time, from state to state and from one kind of CAFO to the next. And even excellent oversight isn't always enough.

In 1995, in one of the worst environmental accidents in U.S. history, over 25 million gallons of waste was spilled from a CAFO into North Carolina's New River. Not only did this kill millions of fish, amphibians and other wildlife, it also caused serious public health problems for humans including an outbreak of Pfiesteria piscicida, an organism that causes skin burning, nausea, muscle cramps and mental problems including memory loss and disorientation.

Any alternative to CAFOs requires a holistic approach to meeting the nutritional needs of over seven billion people. The fact that CAFOs bring low-cost animal protein to millions of people can't be ignored -- nor can the numerous health problems (cancer, cholesterol, diabetes, heart disease, etc.) associated with diets high in meat.

Advocates for more sustainable agriculture call for tougher regulation of CAFO facilities, ending subsidies for factory farms and production of grain and other animal feed, encouraging healthy diets higher in plant proteins with more fruits and vegetables, and internalizing the costs associated with CAFO-related air and water pollution.