Public Health Impacts of CAFOs

The manure output of a single large CAFO can rival the amount of waste produced by the entire human population of some cities. It is costly to transport massive amounts of manure, so it is usually applied within a few miles of the CAFO. Repeated applications, especially in CAFO-dense areas, can result in pollution hotspots. Like human waste, livestock manure can contain significant numbers of pathogens (microbes capable of causing disease). Unlike human sewage, livestock manure does not require treatment to reduce pathogen levels before land application. Leaching and runoff of excess nutrients, pathogens, and other harmful substances can contaminate groundwater and surface waters, poisoning rural drinking water supplies, risking infectious diseases, and causing harmful algal blooms.

The agricultural industry touts nutrient management plans (NMPs) and other conservation practices as the answer to nearly all objections to CAFOs. However, NMPs are primarily designed to optimize crop growth and dispose of manure containing excess nutrients (potential pollutants). They do not adequately protect the environment and safeguard human health. Numerous other regulatory deficiencies, such as the exemption of CAFOs from toxic air emissions monitoring and reporting requirements and the lack of transparency regarding on-farm antibiotic usage, contribute to their public health harms.

Regulatory loopholes allow many large CAFOs to skirt existing rules. State CAFO immunity laws (“right-to-farm” statutes) often preempt local zoning ordinances. Generally, there are no CAFO size or density restrictions, even in watersheds impacted by agricultural pollution and declared impaired under the Clean Water Act. Unchecked CAFO expansions and new constructions amplify the associated harms. Oversight by public health and medical professionals is woefully inadequate.  

Table 1 summarizes the adverse public health and environmental effects of CAFOs. A four-part series of Fact Sheets focus on the public health risks.

I. INFECTIOUS DISEASES
  • Pathogens (bacteria, parasites, & viruses): Recreational water illnesses, foodborne illnesses (“food poisoning”), zoonoses (infections transmitted to humans from animals)
  • Antibiotic resistance: Emergence and spread
  • Pandemic potential: Influenza A and coronaviruses
II. CONTAMINATION OF DRINKING WATER SOURCES (surface waters and groundwater)
  • Nitrate-nitrogen: Methemoglobinemia (“blue baby syndrome”), pregnancy complications, cancer
  • Pathogens and other contaminants: (growth hormones, antibiotics, chemicals, heavy metals)
III. NUTRIENT WATER POLLUTION (nitrogen and phosphorus)
  • Harmful algal blooms (HAB): Cyanotoxin production (toxic to the liver, kidney, and nervous tissue)
  • Eutrophication: Detrimental to aquatic plant and animal life (dead zones, fish kills)
IV. BEYOND ODOR: HARMFUL AIR EMISSIONS
  • Directly harmful to humans (workers and neighbors/residents): Toxic emissions, respiratory tract irritants, particulate matter (PM) pollution, and bioaerosols (including airborne pathogens and endotoxin)
  • Harmful to the planet/detrimental to humans: Greenhouse gases (methane, nitrous oxide, carbon dioxide), ozone depletion (nitrous oxide), and water pollution (deposition of nitrogen emissions)

Table 1: Adverse public health and environmental effects of CAFOs

Public Health Impacts of CAFOs - Part I - Infectious Diseases.pdf248.34 KB