Adverse Health Effects Of Hog Production
A Literature Review
Ammonia emissions from hog farms pose a serious public
• Ammonia emissions from hog farms react with other gases in the air to form
fine particle pollution, a public health threat linked to decreased lung function,
cardiovascular ailments and most seriously, premature death.1
• Recent analysis by NC State University (NCSU) researchers shows that fine
particulate pollution is higher in Raleigh (and likely for all of the Triangle area)
when air masses cross the high density hog counties on the way to Raleigh.2
This analysis also found fine particulate levels in a rural
town (Kenansville) in a high density hog county were very high relative to what
would be expected.
• The 2003 National Academy of Sciences3 report identified atmospheric ammonia nitrogen emissions as the most significant public health threat from
Animal Feeding Operations4 on a regional scale.
• Reducing ammonia emissions from Animal Feeding Operations makes sense
not only for the obvious public health benefits, but also for economic reasons.
The Benefit Cost Analysis conducted by Research Triangle Institute for the
NCSU hog waste management evaluations found that a 50% reduction in
ammonia emissions from hog farms in eastern NC will provide an
estimated $190 million a year in benefits from avoided health impacts.5
Air emissions from lagoons, sprayfields and hog houses have
been linked to neurological and respiratory problems.
• Subjects in a controlled exposure chamber who were exposed to air from hog operations for one hour reported headaches, eye irritation and nausea.6
• Unpleasant odors have been found to be a nuisance and emotional stressor on
neighbors,7 and are known to contain irritants that can cause damage to mucosal
linings in the nose, throat and respiratory tract.8 • The 2003 National Academy of Sciences report identified odor as the most
significant concern for local communities among the suite of air emission
problems from Animal Feeding Operations.
• Researchers from the UNC School of Public Health and Duke University found
that neighbors exposed to odors from hog operations showed evidence of
reduced immune system function.9
• Evidence is also emerging that indicates that the health of citizens living near
hog operations is negatively affected.10 Research in Iowa and North Carolina showed that neighbors living within three miles of hog operations experience
elevated levels of respiratory complaints relative to those living near other animal
production operations or crop production.11,12 • Abhorrent odors can be exacerbated by the smell and sight of rotting flesh from
hog carcasses that are often stored in “dead boxes” close to neighbors’ property
lines. "Dead trucks" that transport hog carcasses to rendering facilities also emit
Hydrogen Sulfide Emissions
• Hydrogen sulfide (H2S) is a colorless gas with a strong odor of rotten eggs that
is detectable at concentrations as low as 0.5 ppb (0.0007 mg/m3). Acute
exposures to H2S at 2 – 10 ppm have been associated with respiratory and
cardiovascular effects, and people with asthma appear to be more sensitive to
H2S reporting headaches following 30 minute exposures to 2 ppm.13 The EPA
also reports that acute occupational exposures have been associated with a
variety of central
nervous system (CNS) transitory symptoms, such as dizziness, nausea,
headache, and at higher exposure concentrations, serious conditions such as
“abrupt physical collapse” and pulmonary edema.14 • The 2003 National Academy of Sciences report, noting hydrogen sulfide’s risks
to public health, recommended that the EPA and USDA should develop process-
based mathematical models for atmospheric emissions of hydrogen sulfide,
along with ammonia and methane, to identify management changes that
• Of particular concern is the susceptibility of children to neurological effects
associated with H2S exposure.15
• The EPA Office of Air Quality Planning and Standards is in the process of re-
evaluating H2S toxicity to determine if it requires specific regulation.16 The
neurotoxicity has been cited as one of the principle reasons for increased
• In light of these efforts by the EPA Office of Air Quality Planning and Standards,
it would seem reasonable and practical to continue to collect emissions data, and
use this information in the evaluation of potential health impacts that can be used
to inform the decision-making process by the Office of Air Quality Planning and
Standards. It is premature to cease collecting this information at a time when an
analysis of the exposure conditions is warranted.
Hog waste contains disease-causing pathogens & increases
• Hogs and humans share many of the same disease organisms. Large
quantities of antibiotics, many closely related to those used to treat humans, are
used by pork and other livestock and poultry producers.17 • Environment Defense reported in 200518 that North Carolina’s animal production industry, which is largely comprised of hog and poultry production, is
estimated to use three million pounds of antibiotics annually. This is
approximately the same amount of antibiotics that is estimated to be used
nationally to treat humans.
• The vast majority of antibiotics are administered not to treat disease but rather
to promote growth or to compensate for the crowded, stressful and often
unhygienic conditions in industrial-scale livestock operations. An expanding body
of evidence19,20 links this frequent exposure of antibiotics to the development of
antibiotic-resistant pathogens, contributing to the problem of reduced antibiotic
effectiveness in humans, a growing health concern in the United States.
• There are also concerns about the exposure of workers or neighbors to
antibiotics in the dust generated in the hog confinement facilities, which are
21,22 vented to the outdoors.
Evidence indicates adverse impacts on workers’ and children’s
• An enormous amount of research exists to document the serious negative
impacts to swine confinement house workers.23 Effects include respiratory symptoms, reductions in pulmonary function and increased bronchial
• Researchers in Iowa found a high prevalence of asthma in children living on
hog farms, especially farms that added antibiotics to feed.24,25
• A North Carolina study of 58,169 children found a 23% higher prevalence of
asthma symptoms among students attending schools where staff noticed
livestock odors indoors twice a month or more.26
Manure land application rates at hog Animal Feeding Operations
result in high levelsof pollutants in groundwater and pose risks
for drinking water wells.
• Ground water nitrate levels beneath animal waste sprayfields are typically found
to range from 10 to 50 parts per million (ppm).27 The drinking water standard for nitrate is 10 ppm. Even wells drilled to clean aquifers below surface
contaminated groundwater aquifers are at risk because well casing construction
flaws can allow leaks of highly contaminated groundwater into drinking water
• Results from a free well-testing program for people living adjacent to hog farms
in North Carolina in 1996 found more that 10% of the wells tested failed to meet
drinking water standards for nitrate. Three wells had nitrate concentrations in the
70 – 100 ppm range. The NC Department of
Health and Human Services found that the results of the well testing program
“…illustrate a potentially serious groundwater problem to the people utilizing
wells near Industrial Livestock Operations in five counties in eastern North
Community health experts are recommending safeguards to
protect the health of rural residents.
• Based on the 2003 American Public Health Association’s review of evidence of
the health and economic impacts of concentrated animal feeding operations
(CAFOs) 29 30 and “evidence, albeit less certain, indicating impacts on children
and CAFO neighbors from exposure to large concentrations of manure and their
subsequent emissions of dust, toxins, microbes, antibiotics and pollutants in the
air and water,” the Association resolved that it would: Urge federal, state, and
local governments, and public health agencies to impose a moratorium on new Concentrated Animal Feed Operations until additional scientific data on the attendant risks to public health have been collected and uncertainties resolved.
Community health experts are recommending safeguards to
protect the health of rural residents.
• The American Public Health Association's recommendations were recently
endorsed by a collection of American and European environmental scientists
brought together in a symposium and workshop organized by the University of
Iowa’s Environmental Health Science Research Center and sponsored by the
National Institutes of Environmental Health Sciences. The endorsement emerged
from an expert community health workgroup assembled at the workshop in
2004, the results of which were recently published.31 The workgroup found that “…sufficient research exists to support action to protect rural residents from the
negative community health effects of CAFOs….” Furthermore, the expert workgroup recommended that permitting of CAFOs should include: consideration of total animal density in a watershed; environmental impact statements; public meetings and local decision making; regulation with standards applied
to general industry with similar levels of emissions and type of waste handling;
and bonding for manure-storage basins for performance and remediation.
Prepared by Environmental Defense Fund, Incorporated, March 2008
Joseph Rudek, Ph.D., firstname.lastname@example.org 3
References and Notes 1 Research Triangle Institute, 2003. “Benefits of Adopting Environmentally Superior Technologies in North Carolina,” available at http://www.cals.ncsu.edu/waste_mgt/smithfield_projects/phase1report04/appendix%20c- RTI.pdf. 2 Goetz, S.B. 2006. Measurement, Analysis, and Modeling of Fine Particulate Matter in Eastern North Carolina. Master Thesis. NC State University, Raleigh, NC. 3 National Academy of Sciences/National Research Council, 2003. National Air Emissions from Animal Feeding Operations: Current Knowledge, Future Needs, National Academies Press, available at http://fermat.nap.edu/catalog/10586.html. 4 Animal Feeding Operations are defined by EPA as operations where animals have been, or will be stabled and fed or maintained for a total of 45 days or more in any 12 month period and where vegetation is not sustained in the conferment area during the normal growing season. CAFOs or Concentrated Anmal Feeding Operations are essentially large AFOs exceeding a numerical threshold set by regulation. See Section 3.0 in http://www.epa.gov/npdes/pubs/cafo_permit_guidance_chapters.pdf. 5 Research Triangle Institute, 2003. “Benefits of Adopting Environmentally Superior Technologies in North Carolina,” available at http://www.cals.ncsu.edu/waste_mgt/smithfield_projects/phase1report04/appendix%20c- RTI.pdf. 6 Schiffman, S.S, Studwell, C.E., Landerman, L.R., Berman, K, Sundy, J.S., 2005. Symptomatic effects of exposure to dilute air samples from swine confinement atmosphere on healthy human subjects. Environmental. Health Perspectives, v.113:567-576. 7 Schiffman, S.S, Sattely Miller, EA, Suggs, M.S., Graham, B.G., 1995. The effect of environmental odors emanating from commercial swine operations on the mood of nearby residents. Brain Research Bulletin, v.4:369- 375. 8 McBride, A. D., 1998. The Association of Health Effects With Exposure to Odors from Hog Farm Operations. Report from the North Carolina Department of Health and Human Services, State Health Director, available at http://www.epi.state.nc.us/epi/mera/iloodoreffects.html. 9 Avery, R.C., Wing, S., Marshall, S.W., Schiffman, S.S., 2004. Odor from industrial hog farming operations and mucosal immune function in neighbors. Archives of Environmental Health,v.59: 101-108. 10 Thu, K.U., 2004. Neighbor health and large-scale swine production. National Ag Safety Database Review, available at http://www.cdc.gov/nasd/docs/d001701-d001800/d001764/d001764.html. 11 Wing, S. and S. Wolf, 2000. Intensive Livestock Operations, Health, and Quality of Life Among Eastern North Carolina Residents. Envr. Health Perspectives, v. 108(3):233-238. Hog Operations: Health Effects Summary Prepared by Environmental Defense Fund, Incorporated, March 2008 Joseph Rudek, Ph.D., email@example.com 5
12 Thu, K., K. Donham, R. Ziegenhorn, S. Reynolds, P. Thorne, P. Subramanian, P. Whitten, and J. Stookesberry, 1997. A control study of the physical and mental health of residents living near a large-scale swine operation. Journal of Agricultural Safety and Health, v. 3(1): 13-26. 13 National Research Council. 2003. Air Emissions from Animal Feeding Operations: Current Knowledge, Future Needs. Ad Hoc Committee on Air Emissions from Animal Feeding Operations, Committee on Animal Nutrition, National Research Council ISBN: 978-0-309-08705-6. Pages 66 - 68 14 US Environmental Protection Agency (EPA). 2003. Toxicological Review of Hydrogen Sulfide (CAS No. 7783-06-4) In Support of Summary Information on the Integrated Risk Information System (IRIS), June 2003, U.S. Environmental Protection Agency Washington, DCEPA/635/R-03/005 www.epa.gov/iris 15 Hannah RS, Roth SH. 1991. Chronic exposure to low concentrations of hydrogen sulfide produces abnormal growth in developing Purkinje cells. Neurosci. Lett. 122: 225-228. 16 Brat I. 2007. A Gas Under Pressure: Health Concerns May Spur Hydrogen Sulfide Ruling; Move 'Costly' for Industry. Wall Street Journal, December 11, 2007; Page B1. 17 Gilchrist, M.J., Greko, C., Wallinga, D.B., Beran, G.W., Riley, D.G., Thorne, P.S., 2006. The potential of CAFOs in infectious disease epidemics and antibiotic resistance. Envr. Health Perspectives, available at http://www.ehponline.org/members/2006/8837/8837.pdf. 18 Florini, K., Denison, R., Stiffler, T., et al., 2005. Resistant Bugs and Antibiotic Drugs: State and County Estimates of Antibiotics in Animal Feed and Animal Waste, available at http://www.environmentaldefense.org/documents/4301_AgEstimates.pdf. 19 Cui, S., Ge, B., Zheng, J., Meng, J., 2005. Prevalence and antimicrobial resistance of Campylobacter spp. and Salmonella serovars in organic chickens from Maryland retail stores. Applied and Envr Microbiology, v.71: 4108- 4111. 20 Price, L.B., Johnson, E., Vailes, R. Silbergeld, E., 2005. Fluorquinolone-resistant Campylobacter isolates from conventional and antibiotic-free chicken products. 21 Hamscher, G., Pawelzick, H.T., Sczesny, S., Nau, H., Hartung, J., 2003. Antibiotics in dust originating from a hog fattening farm: a new source of health hazard for farmers? Envr. Health Perspectives, v. 111:1590-1594. 22 Chapin, A., Ruke, A., Gibson, K., Buckley, T., Schwab, K., 2005. Airborne multidrug-resistant bacteria isolated from a concentrated swine feeding operation. Envr. Health Perspectives, v. 113:137- 142. 23 Dosman, J.A., Lawson, J.A., Kirychuk, S.P., Cormier, Y., Biem, J., Koehncke, N., 2004. Occupational asthma in newly employed workers in intensive swine confinement facilities. European Respiratory Journal, v. 24:698-702, available at http://erj.ersjournals.com/cgi/content/full/24/4/698. 24 Merchant, J.A., Naleway, A.L., Svendsen, E.R., Kelly, K.M., Burmeister, L.F., Stromquist, A.M., Taylor, C.D., Thorne, P.S., Reynolds, S.J., Snaderson, W.T., Chrischilles, E.A., 2005. Asthma and Farm Exposure in a cohort of rural Iowa children. Envr Health Perspectives, v. 113:350-356, available at http://www.ehponline.org/members/2004/7240/7240.pdf. 25 Chrischilles, E., Ahrens, R., Kuehl, A., Kelly, K., Thorne, P., Burmeister, L., 2004. Journal Allergy Clin. Immunol, v. 113:66-71. 26 Mirabelli, M.C., Wing, S. Marshall, S.W., Wilcosky, T.C. 2006. Asthma symptoms among adolescents who attend public schools that are located near confined swine feeding operations. Pediatrics, v. 118:66-75. 27 Showers, Bill. Progress Report: Stable Nitrogen Isotopic Tracers of Excess Nitrogen Sources to the Neuse River Basin Estuary and Nearshore Waters, April 1, 1998. NC State University Stable Isotope Laboratory. 28 Rudo, Kenneth. Memo to Dennis McBride, State Health Director, RE: Nitrate Well Water Testing Program
Adjacent to Intensive Livestock Operations. August 14, 1998.
29 American Public Health Association. 2003. Policy Statements. http://www.apha.org/legislative/policy/2003/2003-007.pdf 30 A CAFO (concentrated animal feeding operation) is a large AFO (Animal Feeding Operation) See endnote 4. Most of North Carolina’s hogs are grown in CAFOs. 31 Donham, K.J., Wing, S., Osterberg, D., Flora, J.L., Hodne, C., Thu, K.M., Thorne, P.S. 2006. Community health and socioeconomic issues surrounding CAFOs. Environmental Health Perspectives. http://www.ehponline.org/members/2006/8836/8836.pdf.