food Program

Public Health

Public Health

Factory farms make awful neighbors. Ask anyone who’s endured the nauseating stench of a manure lagoon constructed right beside her home. When a factory farm  G moves in, the surrounding community deteriorates, the local economy stagnates, property values plummet, and the oppressive odor permeates everything: furniture, carpets, clothes, drapes, blankets, beds... 

Obviously, this dramatically reduces the quality of life in rural communities.  Perhaps less apparent is the fact that factory farms also jeopardize the health and safety of neighbors, employees, and the general public.  They do so by contaminating ground and surface water, releasing harmful pollutants into the air, promoting the development of antibiotic-resistant bacteria, incubating infectious diseases, and facilitating the continued overuse of chemical pesticides.

So great is the public health threat posed by factory farms that the world’s largest association of public health professionals, the American Public Health Association (APHA), issued a resolution urging state and local officials to impose a precautionary moratorium on the construction of new factory farms.  F

Antibiotic Resistance

As a result of the confined, crowded, and unsanitary conditions found on factory farms, animals are stressed and prone to sickness. Rather than improving these squalid conditions, factory farm owners routinely add low doses of antibiotics  G to animal feed. In addition to preventing widespread disease, the use of antibiotics benefits factory farms by artificially boosting animals' growth rates. As a result, huge quantities of antibiotics are currently fed to animals on factory farms; according to the FDA, approximately 80% of all antibiotics used in the United States are fed to farm animals for nontherapeutic purposes.  F

Unfortunately, routine administration of antibiotics has the harmful effect of promoting the development of antibiotic-resistant bacteria. Although the low dosage of antibiotics kills many bacteria, the stronger bacteria that survive can reproduce and pass their resistance to future generations. Since bacteria are able to reproduce in as little as 20 minutes, routine administration of antibiotics can induce the rapid development of antibiotic-resistant bacteria, which can spread directly to humans and animals.  FWhen manure is spread onto fields or stored in manure lagoons, these bacteria can also contaminate waterways and groundwater.  In fact, scientists have detected antibiotic-resistant bacteria in groundwater as far as 250 meters away from manure lagoons.  F

As antibiotic-resistant bacteria spread, medicines used to treat human diseases can become less effective, which poses a significant threat to public health.  The Institute of Medicine estimates that antibiotic-resistant bacteria cause US health care costs to increase by four to five billion dollars each year.  F

Water Pollution

Factory farms are responsible for polluting surface water and groundwater.  In addition to degrading fragile aquatic ecosystems, this poses a substantial threat to human health.

As described in the Water Pollution issue page, factory farms produce a tremendous amount of excess animal waste, which is stored in lagoons and often over-applied to surrounding land.

As a result of manure spills, leaky lagoons, and runoff from over-saturated land, pollutants in animal waste are carried into surface water and groundwater.  These pollutants can contaminate public and private water sources, jeopardizing the health and safety of communities that rely upon these supplies for drinking water.  

Harmful water pollutants from factory farms:

Manure contains high levels of nitrogen, a nutrient which, when combined with oxygen, forms nitrate. Since factory farms produce huge quantities of manure, they can cause nitrate to rapidly accumulate in ground and surface water.

High levels of nitrate in drinking water can cause infants to develop methemoglobinemia, or “blue baby syndrome.”  This condition reduces the oxygen-carrying capacity of the infant’s blood, and can be fatal if left untreated.  FAccording to the EPA, long-term exposure to high levels of nitrate may cause adults to suffer from diuresis, increased starchy deposits, and hemorrhaging of the spleen.  F

In US counties with factory farms, approximately 1.3 million households rely on water wells in which nitrate levels exceed the Maximum Contaminant Level set by the EPA.  F

Animal manure can carry a variety of harmful pathogens (living microorganisms that cause disease), including Campylobacter, Cryptosporidium parvum, E. coli, and Salmonella.  These pathogens cause a wide range of human health disorders of varying severity; while certain pathogens might induce mild ailments such as cramps, stomach pain, nausea, diarrhea, or vomiting, pathogens can also cause fever, kidney failure, and even death.  F F F

Vulnerable populations such as children, the elderly, and those with weakened immune systems are particularly susceptible to developing serious medical conditions or life-threatening infections after exposure to pathogens.  F F F FSince pathogens can remain in manure, soil, and water for weeks (or in some cases, months), they pose an ongoing threat to public health.  F 

Other Pollutants
When animals are pumped full of drugs and growth enhancers on factory farms, their waste contains residues of these substances; as a result, factory farms can contaminate ground and surface water with pollutants such as hormones, antibiotic-resistant bacteria, salts and heavy metals.  F F F F

Hormones: Growth hormones administered to livestock can pass into their manure.  FResearch suggests that exposure to hormones may be linked to breast and testicular cancers in humans.  F

Antibiotic-Resistant Bacteria: As described above, antibiotics can pass into manure, spawning the development of antibiotic-resistant pathogens, which can cause infections that are resistant to treatment with conventional antibiotics.

Salts: This component of animal waste can increase salt levels in drinking water, potentially raising the blood pressure of salt-sensitive individuals.  FHigh salt concentrations can cause groundwater to become undrinkable.  F

Heavy Metals: Included in animal feed to promote growth, trace amounts of heavy metals such as arsenic and copper are excreted in animal waste; these pollutants can contaminate water, and may damage human health.  F 

Outside the community
The health impacts of water pollution from factory farms extend far beyond the communities immediately surrounding these operations; pollutants from factory farms contaminate lakes, rivers, and streams, making them unsafe for swimming, fishing, and other recreational uses.  
Almost 40 percent of the nation’s surveyed waters are so polluted they're unsafe for swimming or fishing.  FAccording to the EPA’s 2000 National Water Quality Inventory, agricultural sources were responsible for polluting 128,859 miles of surveyed rivers and streams, 3,158,393 acres of surveyed lakes, and 2,811 square miles of surveyed estuaries.  F

Toxic Algal Blooms

Pollution from factory farms also contributes to nutrient overloading in coastal waters, which is thought to cause outbreaks of Pfiesteria piscicida and other toxic algal blooms.  FExposure to Pfiesteria can cause a variety of human health problems including neurological damage, memory loss, confusion, respiratory ailments, skin problems, and gastro-intestinal illness.  F FNumerous Pfiesteria outbreaks have occurred in coastal waters from Delaware to North Carolina.  F 

For more information about water pollution caused by factory farms, visit the Water Pollution page.

Air Pollution
Factory farms also threaten human health by releasing a host of harmful air pollutants.  Emitted from confinement buildings, waste stored in manure lagoons, and from the land on which manure is spread or sprayed, the most significant air pollutants are the hazardous gases derived from urine, manure, and the decomposition of these animal wastes, as well as the particulates from feed, animals, and animal waste.  F

Major Air Pollutants:

Hydrogen Sulfide (H2S)
This colorless, highly toxic gas is among the most dangerous pollutants emitted by factory farms. Exposure to high levels of hydrogen sulfide causes rapid loss of consciousness, shock, pulmonary edema, coma and death.  FExposure to levels of 500 ppm (parts per million) or greater are likely to be lethal;  Flevels above 600 ppm can kill a person after only one or two breaths.  F

Exposure to very low concentrations of hydrogen sulfide – even levels well below the thresholds for irritation or toxicity – can also cause health problems;  Fstudies have linked low levels of exposure to cough, throat irritation, eye symptoms, nasal symptoms, and headache.  FOther symptoms include nausea, stomach distress, coughing, headache, dizziness, and blistering of the lips.  F

Long-term exposure to low levels of hydrogen sulfide is associated with anosmia, the loss of ability to detect odors.  FResearch indicates that low-level exposure can also cause neuropsychologic abnormalities such as impaired balance, visual field performance, color discrimination, hearing, memory, mood, and intellectual function.  F

Hydrogen sulfide is particularly dangerous because the intensity of its characteristic rotten-egg-like odor increases only slightly at levels above 6 ppm. At concentrations of 150 ppm or higher, the gas can actually reduce humans' sense of smell, rendering individuals vulnerable to harmful levels of exposure.  FFurthermore, when manure pits are agitated, the concentration of hydrogen sulfide can rise to deadly levels within seconds.  F 

Ammonia (NH3)
Emitted by animal waste and during the waste treatment process, this pungent toxin is readily absorbed in the upper airways.  FExposure can cause wheezing, shortness of breath, and irritation of the eyes, throat, respiratory system, sinuses, and skin.  F F 

Research suggests that exposure to moderate concentrations of ammonia (50-150 ppm) can cause humans to develop severe cough and mucous production; higher concentrations (above 150 ppm) can cause scarring of the upper and lower airways, reactive airways dysfunction syndrome (RADS), persistent airway hypersensitiveness, lower lung inflammation, and pulmonary edema.  FExposure to extremely high concentrations of ammonia may be fatal.  F  

Particulate Matter
Particulate matter is composed of large and small particles of various solids or liquids suspended in the air.  Particulate matter emitted by factory farms may include fecal matter, feed materials, skin cells, and bioaerosols such as bacteria, fungi, spores, viruses, pollens, endotoxins, exotoxins, and products of microorganisms.  F

Research indicates that long-term exposure to dust particles from factory farms can lead to persistent respiratory symptoms and a decline in lung function.  FExposure to bioaerosols may induce asthma, cough, chest tightness, and hypersensitivity pneumonitis (“farmer’s lung”).  F

Dust particles may also absorb harmful gases such as ammonia or hydrogen sulfide, allowing these substances to be drawn deep into the lungs, thereby intensifying their harmful effects.  F 

The most obvious air pollutant emitted by factory farms is odor; indeed, the awful stench of a factory farm can be readily observed for miles.

Odor is comprised of a complex mixture of chemicals produced by bacteria as they break down food in animals' digestive systems, and as they decompose manure that has been excreted.  FIn one study, researchers identified 331 fixed gases and volatile organic compounds (VOCs) in samples of air emitted from factory farms in North Carolina.  F

In addition to drastically diminishing the quality of life of those living in the surrounding communities, odor from factory farms can adversely affect human health.  FResearchers at North Carolina State University’s field laboratory determined that when exposed to simulated CAFO  G emissions for one hour, subjects were 4.1 times more likely to develop headaches, 6.1 times more likely to report eye-irritation, and 7.8 times more likely to report nausea than those who breathed clean air.  F

Exposure to odor from factory farms has also been linked to nasal irritation, diarrhea, hoarseness, sore throat, cough, chest tightness, nasal congestion, palpitations, shortness of breath, stress, drowsiness, and alteration in mood.  F 

Factory Farm Workers
Those who work in factory farms are routinely exposed to a range of hazards known to cause a variety of well-documented health problems, some of which may be irreversible.  F 

As a result of repeated inhalation of harmful air pollutants, respiratory ailments are particularly common among factory farm workers.  According to a study published by Iowa State University, as many as 70 percent of CAFO workers experience acute bronchitis; 25 percent suffer from chronic bronchitis, which causes chronic phlegm for two or more years.  F

Up to 20 percent of current factory farm workers suffer from non-allergic occupational asthma, asthma-like syndrome, and/or reactive airways disease, which can lead to a progressive decline in lung function and chronic obstructive pulmonary disease, an irreversible condition.  F

Research also indicates that factory farm workers often suffer from health disorders such as sinusitis, rhinitis, cold symptoms, headache, chest tightness, wheezing, cough, and chronic declines in lung functions.  F

Additional risks
Workers also risk severe health problems due to potential exposure to hydrogen sulfide.  While acute or chronic exposure to the toxic gas can cause acute respiratory distress syndrome (ARDS) or pulmonary edema, high concentrations can be deadly, and are known to have caused fatalities at numerous CAFOs.  F Hydrogen sulfide is especially dangerous since concentrations can quickly rise to deadly levels when a manure lagoon is agitated (which commonly occurs before lagoons are pumped out).

Factory farm workers are also exposed to diseases contracted by animals within the facilities.  FAs a result of the routine overuse of antibiotics, they may be exposed to antibiotic-resistant bacteria as well – these bacteria can cause infections that are resistant to the antibiotics used to treat humans.

Air pollutants from factory farms damage the health of those who live in surrounding communities as well.  Although hazardous gas and particulate levels are generally lower in these areas than within factory farms, community residents endure constant exposure to the pollutants; unlike factory farm employees, neighbors can’t discontinue their exposure at the end of each workday.

Furthermore, surrounding communities include vulnerable populations such as children, the elderly, asthmatics, and people with weakened immune systems, all of whom may be harmed by lower levels of air pollutants.  F

Additional research is required to fully understand the complex impacts of industrial livestock operations on the health of those living in surrounding communities.  However, several studies have demonstrated that factory farms adversely affect the health of those living nearby.

A University of Iowa study revealed that those living within two miles of a factory farm reported higher rates of respiratory problems, nausea and weakness, headaches and plugged ears, and irritation of eyes, nose and throat than other rural residents.  F

A study conducted by researchers from the University of North Carolina determined that individuals living near a factory farm experienced increased occurrences of headaches, runny noses, sore throats, excessive coughing, diarrhea, and burning eyes than those living in areas without industrial agriculture operations.  F

It should also be noted that factory farms diminish the quality of life in surrounding communities, and undoubtedly affect the mental wellbeing of neighbors.  FA study conducted in North Carolina revealed that those living near swine factory farms experienced more tension, anger, fatigue, confusion, and total mood disturbance than those not living near such facilities.  F

Public Health Threats

Factory farms indirectly threaten public health by utilizing huge quantities of feed grown with chemical pesticides.  Many of these substances are known to cause cancer, suppress the immune system, and interfere with the nervous, endocrine and reproductive systems.  FFurthermore, scientists note that few pesticides have been adequately tested for safety; the long-term health effects of pesticides and the impact of exposure to multiple pesticides (the "cocktail effect") are especially uncertain.  FNonetheless, according to the EPA, over five billion tons of pesticides are used in the US every year.  F

Mad Cow Disease
Irresponsible factory farming practices have also increased the risk of spreading mad cow disease (bovine spongiform encephalopathy).  In order to boost the protein content of their animals' feed as cheaply as possible, factory farms routinely add animal byproducts.  This practice dramatically increases the risk of spreading mad cow disease, which is contracted by cattle when they eat the blood or meat of infected cows.

Since consumption of infected meat can cause humans to contract a fatal illness called variant Creutzfeldt-Jakob Disease, or vCJD (the human form of mad cow disease),  Fan epidemic of mad cow disease would pose a substantial threat to public health.

Although the 1997 Feed Ban was supposed to minimize this risk by prohibiting ruminant protein from being fed to other ruminants, it included several gaping loopholes.  For instance, cattle feed can still contain “plate waste” from restaurants, which can include beef.  FCows can also be fed poultry, despite the fact that poultry feed can include cow remains.  FFurthermore, cows can be fed poultry litter, a mix of feces, feathers, and uneaten poultry feed, which can also include cow remains.  F

Despite the discovery of a case of mad cow disease in the US in December 2003 and a second case in June 2005, the FDA has yet to eliminate the loopholes in the Feed Ban. 

Infectious Disease Transmission
Factory farms also threaten human health by incubating infectious diseases that can spread to the human population.  Diseases can be transferred directly from animals to humans, or from an animal serving as a “mixing vessel” for a new strain of a disease.  FIn cases of direct transmission, a worker who comes in contact with a diseased animal or its manure can contract the disease and pass it on to family and the surrounding community.  F

In other cases, an animal infected with one disease can contract a second disease from another animal, causing the diseases to mix and form a new type of illness.  FFor instance, scientists suggest that a virus passed from hogs to humans may have caused the 1918 “Spanish Influenza” pandemic which eventually killed 40 million people worldwide.  F FThe Centers for Disease Control has expressed concern that another similar epidemic will occur in the future.  F 

The Alternative!
Fortunately, it’s possible to produce food without damaging human health – sustainable farms do so every day!  Unlike their industrial counterparts, sustainable farms operate without jeopardizing the health and safety of workers, neighbors, or the general public.

In fact, these farms typically enhance surrounding communities by preserving greenspace, providing habitat for wildlife, and stimulating the local economy. (For more information, see the Farms & Communities page.)

Since sustainable farms raise animals on adequately-sized plots of land, animal waste can be used to fertilize the surrounding farmland rather than being collected and stored in huge manure lagoons.  As a result, sustainable farms are able to raise animals without polluting ground and surface water, contaminating wells, or fouling the air with harmful pollutants.

Sustainable farms also refrain from utilizing hormones, nontherapeutic antibiotics, and harmful feed additives.  This keeps animals healthy, eliminates potential sources of water contamination, and helps prevent the proliferation of antibiotic-resistant bacteria.
In addition to protecting the health and safety of workers and neighbors, sustainable farms produce nutritious foods that improve the health of consumers.  For more information about the health benefits of sustainable foods, visit the Personal Heath & Nutrition page.


  • A study conducted by Iowa State University found that nearly 70% of all swine confinement workers suffer from some form of respiratory illness or irritation.  F  Researchers determined that 10% of swine confinement workers experience toxic organic dust syndrome (TODS) and 58% suffer from chronic bronchitis.  F 
  • Animal agricultural operations produce nearly 73% of all ammonia air pollution in the US.  F 
  • A study in California revealed that dairy operations generated 88% of the agricultural salt load within the dairy area.  F 
  • Researchers have found antibiotics at concentrations as high as 12.5 mg/kg dust within dust collected within hog confinement houses.  F 
  • In the US, an estimated 700,000 persons work in animal confinement operations where they risk exposure to a variety of well-documented human health hazards.  F 
  • According to the US Geological Survey, in the US, groundwater provides drinking water for more than 97% of the rural population who lack access to public water-supply systems.  FGroundwater is also the source of approximately 40% of all water used for public water supply systems.  F 
  • Although the government monitors public water supplies, private water wells aren’t required to undergo routine safety testing.  FAs a result, families that rely upon private wells are particularly vulnerable to the harmful effects of factory farm pollutants.
  • About half of the gaseous ammonia emitted by factory farms is deposited by rain or fog within 50 miles; the remaining ammonia is turned into dry particles, which can travel as far as 250 miles!  F 
  • The average adult male inhales as much as 33 pounds of air per day.  F