Environmental impact of pig farming

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Farms often pump their animal waste directly into a large lagoon, which has environmental consequences.
Pigs in a CAFO

The environmental impact of pig farming refers to the threats posed to the natural environment by large-scale intensive pig farming. Industrial pig farming, a subset of concentrated animal feeding operations (CAFOs), poses numerous threats to the environment. CAFOs house thousands of swine and other farm animals in confined areas, where feces and waste often spread to surrounding neighborhoods, polluting air and water with toxic waste particles.[1] Waste from these farms have the potential to carry pathogens, bacteria (often antibiotic resistant), and heavy metals that can be toxic when ingested.[1] Pig waste also contributes to groundwater pollution in the forms of groundwater seepage and waste spray, which is essentially the usage of a sprinkler to spray vats of pig waste into neighboring areas. The contents in the spray and waste drift have been shown to cause mucosal irritation,[2] respiratory ailment,[3] increased stress,[4] decreased quality of life,[5] and higher blood pressure.[6] This improper way to get rid of waste is an attempt for CAFOs to be cost efficient. This presents an environmental injustice problem, since the communities do not receive any benefit from the operations, and instead, suffer negative externalities, such as pollution and health problems.[7] The Agriculture and Consumer Health Department has stated explicitly that the "main direct environmental impact of pig production is related to the manure produced.[8]

North Carolina[edit]

In 2014, National Geographic wrote a piece on the extent of the contamination in North Carolina. Swine sales in the state (second largest pork producer in the nation) were nearly $3 billion in 2012, and the state received attention in 1999 when Hurricane Floyd caused waste pods on the swine ponds to overflow, polluting the water supply. National Geographic suggested that despite the execution of a $17 million research project on waste in the area, no one in the state seemed to know what to do with the pig waste, which was a huge issue considering that there are nearly as many pigs as people.[9] Nearly two decades later when Hurricane Florence hit the coast of North Carolina in 2018, hog waste remained a major concern. According to the NC Pork Council, 98% of hog lagoons experienced minimal impact.[10] The NC Department of Environmental Quality identified six hog farms with anaerobic lagoons that suffered structural damage and 28 farms that had lagoons overflow due to the floodwater.[10]

Effects on water quality[edit]

A typical waste lagoon in North Carolina.

Many of these CAFOS store the swine waste in giant vats often referred to as lagoons. These lagoons often contain pathogens such as salmonella, pharmaceuticals like antibiotics and antimicrobials, as well as nitrogen and phosphorus. This can lead to widespread pollution within the watershed that the CAFO is located within, if the water from these lagoons leaches out into the soil and trickles down into the water table beneath.[11] Unlike human sewage, which is always treated with chemical and mechanical filtration, the waste from these lagoons is untreated when it is released back to the environment. Spills are the most common contributor to pollution, but regardless of spills, toxic nutrients like nitrates and ammonia can seep into the water table located just below the surface, infecting the groundwater that nearby communities drink.[12] It has been estimated that 35,000 miles of river across over 20 states has been contaminated by manure leakage.[13] Some of the causes for the environmental problems are inadequate sewage treatment and lack of developing technologies. Many farms lack adequate wastewater treatment systems, which release untreated wastewater to release into the environment in the form of contamination.[14]

Some spills and leakage of contaminated waste are not accidental. In 2014, Mark Devries used spy drones to expose pig farms in North Carolina that were spraying untreated fecal waste into the surrounding areas, allowing the waste to dissipate into far-off communities.[15] Smithfield Foods, the company responsible for one such factory, claimed this was a tactic used to fertilize its fields. It is true that historically hog feces have been used as fertilizer and can be done safely and without runoff, but the magnitude was described by Dan Whittle, a former senior policy associate at the North Carolina Department of Environment and Natural Resources, as a "mass imbalance", with far too great a magnitude of fecal matter being sprayed for the crops being generated to not have significant spill off into neighboring plots of land.[15] Many residents of the surrounding areas of such farms complain that the industrially concentrated fecal matter creates an unbearable odor of a different magnitude than typical farm manure. Charlotte Savage, a resident who lives on a property separated from the Smithfield farm by an 80-foot path of forest, reported seeing her husband Julian faint at one point due to the smell, and that their house was also once surrounded by a three foot deep puddle of fecal matter. This was described as a common occurrence in this community and many others.[16]

Effects on air quality[edit]

Communities located near CAFOs experience negative health and environmental effects due to several factors associated with industrial pig farming. One main issue that arises out of intensive animal agriculture is the waste that the huge number of animals in a small space produce. In the pig farming industry, there are huge amounts[clarification needed] of waste and farmers are pressed to find somewhere to put it and dispose of it. Pig waste is similar to human waste; filled with bacteria and high amounts of ammonia. At most CAFOs, hog waste is kept in large open-air pits called lagoons where waste is broken down by anaerobic bacteria and then sprayed onto crops as fertilizer. This is called the lagoon and sprayfield system and remains legal in the United States, including in states like North Carolina[17] where there have been on-going efforts in the NC legislature to ban open-air lagoon and sprayfield system practices in the state and replace these with more environmentally-sound waste management practices.[18][19]

The waste then reaches neighboring towns, resulting in civilians not being able to even leave their house in order to avoid pig waste filled air. People living in nearby towns have suffered a variety of adverse health effects including respiratory diseases, infections, increased risk of cancer, and other health risks.[20]

The excessive amounts[clarification needed] of nitrogen from the waste can also contribute to acid rain in the local areas; team of scientists from the US Agricultural Research Service and the US Department of the Environment has examined and noted that within wastewater lagoons in North and South Carolina, there are a host of genes involved in the process of turning ammonia into nitrogen.[21]

One case study, conducted by Environmental Health Perspectives, sought to prove that malodor and pollutant concentrations from swine operations are associated with stress, altered mood, and increased blood pressure. For two weeks, adult volunteers living near swine operations in North Carolina sat outside for ten minutes twice a day. They reported levels of hog odor, and recorded their blood pressure. The study found that like noise and other similar environmental stressors, the malodors from the swine operations were likely associated with an increase in blood pressure, which could contribute to an increase in chronic hypertension.[20]

Disease spread[edit]

There are many documented incidences of disease outbreaks occurring due to the presence of pig farms in a given community, particularly industrial pig farms. MRSA (Methicillin-resistant Staphylococcus aureus, a type of anti-biotic resistant bacteria) outbreaks have been correlated to an individual working in a pig farm, likely attributed to the strong antibiotics often used in industrialized pig farms.[22] Other diseases can also spread in pig farms such as Salmonella, Toxoplasma, and Campylobacter.[23] Granted that many of these diseases are preventable given proper safety precautions such as washing hands and clothes, wearing face masks, and covering any open wounds when coming into contact with pigs, but many improvements could be made to educate farmers on how to protect themselves. Improvements in these areas are often cited as the reason for the lack of increase in disease outbreaks in North Carolina despite an increase in pig population by a factor of four in the years leading up to 1998.[24] In order to prevent disease spread in the community as well, citizens in nearby towns as well as farmers must be educated and equipped with the proper tools and resources to protect themselves from the spread of fecal matter and associated diseases.

Policy implications[edit]

In the 1970s, a series of laws, known as "Murphy's Laws", were passed in North Carolina to eliminate the sales tax on hog farm equipment and to prevent authorities from using authority to prevent and address odor issues.[25] After the passage of Murphy’s Laws and other similar bills, there was a rapid increase in industry in North Carolina, where the population of swine was estimated around 9-10 million.[26] Each of those hogs produces eight times the feces as a human, causing a crucial need for regulation and maintenance for that waste.[27]

Regulation and laws could not keep up with the rapid explosion of the hog farming and spread of CAFOs in the early 2000s, which has caused severe harm and health impacts over time. Furthermore, agencies with jurisdiction over CAFOs are typically environmental or natural resource state-run agencies, as opposed to local health departments. This is an advantage for addressing environmental impacts but a disadvantage for human health concerns, as the majority of local health issues get overlooked by state-run agencies.[28] Additionally, although there are laws and regulations in place, such as the Swine Farm Environmental Performance Standards Act, which prohibits new waste lagoons and mandates that new CAFOs must use technology that will prevent discharge of waste, these regulations do not mandate for existing CAFOs to clean up or regulate the pollutants within their lagoons.[29] These regulations also make it more costly to clean up these wastes and prevent other consequential harms, without actually assisting farms in shouldering these costs, making it difficult for them to actually act on these regulations.

Ag-gag laws have made it even more difficult for farms to be held accountable for their actions, and for communities to have a transparent view of farm operations. These laws forbid the undercover video-taping or documenting of farms without the consent of the farm's owner. These laws are targeted at keeping animal rights and environmental activists away from the most damaging farm operations.[30] These laws emerged in the 90's and are now in effect in North Carolina, Utah, Missouri, Idaho, and Iowa, and is being considered in at least five states. These bills have the potential to exacerbate animal abuse on these large scale farms and CAFOs, as well as threaten community health, social justice, and consumer health by restricting organizations and individuals from sharing pertinent information about the food supply.[31]

The EPA does require that operations with qualified number of pigs must demonstrate that there is no runoff from their farm, in order for them to acquire a permit. But, this regulation varies from state to state and most of the time, enforcement only happens in response to citizen complaints, rather than active monitoring.[32] Further, locally developed policies often have inefficient resources and abilities to enforce regulation, and often don't address transboundary issues that arise with pig operations that exist across multiple states. And with Federal laws such as the Clean Water and Clean Air act, regulation is delegated to state agencies, but these agencies don't usually take on active regulation until the damage has been done. Further, many operations are exempt because they have been grandfathered in, meaning they have been in operation for so long that they are not subject to the new laws.[32]

See also[edit]


  1. ^ a b Nicole, Wendee (2017-03-01). "CAFOs and Environmental Justice: The Case of North Carolina". Environmental Health Perspectives. 121 (6): a182–a189. doi:10.1289/ehp.121-a182. ISSN 0091-6765. PMC 3672924. PMID 23732659.
  2. ^ Wing, S; Wolf, S (2017-03-01). "Intensive livestock operations, health, and quality of life among eastern North Carolina residents". Environmental Health Perspectives. 108 (3): 233–238. doi:10.1289/ehp.00108233. ISSN 0091-6765. PMC 1637983. PMID 10706529.
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  5. ^ Bullers, Susan (2005). "Environmental Stressors, Perceived Control, and Health: The Case of Residents Near Large-Scale Hog Farms in Eastern North Carolina". Human Ecology. 33 (1): 1–16. doi:10.1007/s10745-005-1653-3. ISSN 0300-7839.
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