Environmental Health Impacts of CAFOs

Environ Health Perspect 115:2-8 (2007). doi:10.1289/ehp.10124 available via http://dx.doi.org [Online 19 June 2007]

Referencing: Monitoring and Modeling of Emissions from Concentrated Animal Feeding Operations: Overview of Methods

I am concerned about the development and content of the Mini-Monograph on Environmental Health Impacts of Concentrated Animal Feeding Operations (CAFOs) (Bunton et al. 2007; Burkholder et al. 2007; Donham et al. 2007; Gilchrist et al. 2007; Heederik et al. 2007; Thorne et al. 2007). Although I believe that the process of developing these reports was flawed, I will limit my comments to the content of the reports. It is difficult to comment on six separate articles within the word limitations of a letter; therefore, I will make some general comments followed by a few specific examples.

Overall, there was a wide variation between the six articles (Bunton et al. 2007; Burkholder et al. 2007; Donham et al. 2007; Gilchrist et al. 2007; Heederik et al. 2007; Thorne et al. 2007) in both tone and scientific rigor. However, generally the authors did not differentiate between potential risks associated with general animal production—regardless of facility type—and risks associated with CAFOs. Their default was to assign any potential risk to the attribute "CAFO" rather than the attribute "animal." For example, Burkholder et al. (2007) gave the impression that pathogens in manure would not exist in manure from animals raised in facilities that do not meet the definition of a CAFO. The authors of these articles generally referred to risk as the presence of potential pathogens or toxic substances. A true assessment of potential risk requires an assessment of exposure as well as volume or presence (National Research Council 1994), something that was not addressed to any extent in these reports.

Additionally, Burkholder et al. (2007) did not in any way differentiate between the normal operation of a CAFO and potential impacts on water quality versus the results of a single catastrophic event, such as failure of a lagoon wall. Repeated reference to a single catastrophic event involving a single lagoon does not aid scientists or the public in understanding how CAFOs are operated on a daily basis, or how the typical handling of manure under daily operation may impact water quality. The authors did not attempt to document regulatory oversight or best management practices that have been implemented to minimize potential negative impacts on the environment (U.S. Environmental Protection Agency 2002). Indeed, there was no mention of the relative rarity of lagoon failure, leaving the impression that this is a common event.

In some cases, where the authors attempted to assign risk to CAFOs rather than to animals, they presented biased opinion rather than fact. For example, Gilchrist et al. (2007) stated that

Pathogens tend to be amplified in animals raised in CAFOs and, thus, are more difficult to eliminate in meat packing processes.

This blanket statement does not specify a type of pathogen, but studies indicate that—among the more important pathogens—this is an inaccurate statement. For example, pathogens such as Trichinella spiralis, formerly one of the most prominent pork-associated pathogens, have largely disappeared with the movement of pigs to indoor production (Roy 2003). Furthermore, pork carcass contamination with bacterial pathogens such as Salmonella is consistently lowest in the large packing plants, which because of the large volume of production are most likely to acquire animals from large producers (U.S. Department of Agriculture, Food Safety and Inspection Service 2006). This clearly invalidates the argument that these pathogens are more difficult to eliminate in the packing process.

Gilchrist et al. (2007) also referred to Denmark as a country that has experienced a successful transition to antibiotic-free production. This is incorrect, and indeed the latest DANMAP report (Danish Integrated Antimicrobial Resistance Monitoring and Research Program 2006) indicates that therapeutic antibiotic use in agriculture now exceeds the amount of antibiotics that were used to promote feed conversion before a ban on antibiotic growth promotion. Additionally, pig mortality in Denmark has risen 25% in the last 10 years (Agence France-Presse 2005).

Gilchrist et al. (2007) suggest that industry leaders should take a leadership role in antibiotic use, but they apparently were unaware or intentionally overlooked the fact that the American Veterinary Medical Association, the American Association of Swine Veterinarians (2004), and the National Pork Board (2000) have had prudent use guidelines for 7 years, and that in 2005 the pork industry launched the Take Care — Use Antibiotics Responsibly program (National Pork Board 2005). More than 50 million pigs are marketed each year by producers who recognize the importance of protecting public health and animal health and welfare through the responsible use of antibiotics by pledging their support for the Take Care program.

The topics covered by EHP are important and worthy of public discussion and scientific investigation. However, we do the public, producers, and the research community a disservice when that discussion is driven by misinformation and subjective opinion.

The author is employed by the National Pork Board, which is funded by the Pork Checkoff.

References

Agence France-Presse. 2005. World-leading Pork Exporter Denmark Sees Sharp Increase in Pig Mortality. Available: http://archive.wn.com/2005/09/06/1400/copenhagenbusiness/ [accessed 1 November 2006].

American Association of Swine Veterinarians. 2004. American Association of Swine Veterinarians' Basic Guidelines of Judicious Therapeutic Use of Antimicrobials in Pork Production. Available: http://www.avma.org/reference/jtua/swine/swine99.asp [accessed 10 June 2007].

Bunton B, O'Shaughnessy P, Fitzsimmons S, Gering J Hoff S, Lyngbye M, et al. 2007. Monitoring and modeling of emissions from concentrated animal feeding operations: overview of methods. Environ Health Perspect 115: 303–307; doi:10.1289/ehp.8838 [Online 14 November 2006].

Burkholder J, Libra B, Weyer P, Heathcote S, Koplin D, Thorne P, et al. 2007. Impacts of waste from concentrated animal feeding operations on water quality. Environ Health Perspect 115:308–312; doi:10.1289/ehp.8839 [Online 14 November 2006].

Danish Integrated Antimicrobial Resistance Monitoring and Research Program. 2006. DANMAP 2005 - Use of Antimicrobial Agents and Occurrence of Antimicrobial Resistance in Bacteria from Food Animals, Foods and Humans in Denmark. http://www.danmap.org/pdfFiles/Danmap_2005.pdf [accessed 22 November 2006].

Donham KJ, Wing S, Osterberg D, Flora JL, Hodne C, Thu KM, et al. 2007. Community health and socioeconomic issues surrounding concentrated animal feeding operations. Environ Health Perspect 115:317–320; doi: 10.1289/ehp.8836 [Online 14 November 2006].

Gilchrist MJ, Greko C, Wallinga DB, Beran GW, Riley DG, Thorne PS. 2007. The potential role of concentrated animal feeding operations on infectious disease epidemics and antibiotic resistance. Environ Health Perspect 115:313–316; doi:10.1289/ehp.8837 [Online 14 November 2006].

Heederik D, Sigsgaard T, Thorne PS, Kline JN, Avery R, Bønløkke JH, et al. 2007. Health effects of airborne exposures from concentrated animal feeding operations. Environ Health Perspect 115:298–302; doi: 10.1289/ehp.8835 [Online 14 November 2006].

National Pork Board. 2000. Basic Guidelines of Judicious Therapeutic Use of Antimicrobials in Pork Production for Pork Producers. Available: http://www.pork.org/PorkScience/Documents/psantibicprod.pdf [accessed 10 June 2007].

National Pork Board. 2005. Take Care – Use Antibiotics Responsibly. A Producer's Guide to Using Antibiotics Responsibly. Available: http://www.pork.org/PorkScience/Documents/TC%20Manual%20Page%20by%20Page.pdf [accessed 10 June 2007].

National Research Council. 1994. Science and Judgment in Risk Assessment. Washington, DC:National Academy Press.

Roy SL, Lopez AS, Schantz PM. 2003. Trichinellosis surveillance—United States, 1997-2001. MMWR Surveill Summ 52(6):1–8. Available: http://www.cdc.gov/mmwr/preview/mmwrhtml/ss5206a1.htm [accessed 7 June 2007].

Thorne PS. 2007. Environmental health impacts of concentrated animal feeding operations: anticipating hazards—searching for solutions. Environ Health Perspect 115:296–320; doi:10.1289/ehp.8831 [Online 14 November 2006].

U.S. Department of Agriculture, Food Safety and Inspection Service. 2006. Progress Report on Salmonella testing of raw meat and poultry products 1998-2005. Available: http://www.fsis.usda.gov/Science/Progress_Report_Salmonella_Testing_Tables/index.asp [accessed 22 November 2006].

U.S. Environmental Protection Agency. 2002. Supporting Statement for the Information Collection Request for the Final NPDES and ELG Regulatory Revisions for Concentrated Animal Feeding Operations. Available: http://www.epa.gov/npdes/pubs/cafo_support_for_icr.pdf [accessed 22 November 2006].

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CAFOs: Thorne Responds

Environ Health Perspect 115:2-8 (2007). doi:10.1289/ehp.10124R available via http://dx.doi.org [Online 19 June 2007]

I am pleased that the National Pork Board has read the Mini-Monograph on Environmental Health Impacts of Concentrated Animal Feeding Operations (CAFOs) (Bunton et al. 2007; Burkholder et al. 2007; Donham et al. 2007; Gilchrist et al. 2007; Heederik et al. 2007; Thorne et al. 2007); I hope the board has given consideration to the 26 recommended priority research needs and 16 recommendations for translating science to policy. These were carefully developed by the 31 authors in the five workgroups on Airborne Exposures, Monitoring and Modeling, Water Quality, Infectious Disease Epidemics and Antibiotic Resistance, and Community Health.

Wagstrom states her belief that the process of developing the reports was flawed; because she was not involved in the process, she likely does not know what the process was. In 2002, I convened a group of seven professors, each with decades of experience with this issue and representing environmental health, exposure analysis, occupational medicine, veterinary medicine, environmental policy, water quality, and infectious diseases. We considered existing environmental health problems associated with the industrialization of agriculture and developed goals and plans for the conference. In 2003 we submitted a grant proposal to the National Institutes of Health and, based on extramural peer-review, received a grant to host the conference. We conferred widely with experts in the field to identify those scientists actively engaged in research relevant to the conference topics. We then invited recognized scientists with peer-reviewed publications on the subjects of the workgroups to speak at the plenary session and participate in the ensuing workgroups. In addition, three state regulators provided expertise in exposure modeling. The workgroups considered the problems and formulated a set of research and policy needs that were presented to the full workshop. Based on feedback, these presentations were further developed by the workgroups into articles that were peer-reviewed by EHP before publication in the Mini-Monograph. Multiple levels of peer review are the cornerstone of modern science, and I believe this is the best process to develop science to support environmental health policy.

Wagstrom states that the papers fail to "differentiate between potential risks associated with general animal production—regardless of facility type—and risks associated with CAFOs." As stated in the overview to the Mini-Monograph (Thorne 2007), this conference was focused on industrialized livestock production because this is how > 85% of the pork and poultry in the United States and western Europe is produced. Of U.S. swine production, 54% occurs in 110 industrialized facilities, each housing > 50,000 hogs, and 78.5% occurs in operations with > 5,000 animals (U.S. Department of Agriculture 2007).

Wagstrom states that "a true assessment of potential risk requires an assessment of exposure" and that this "has not been addressed to any extent in these reports." This comment is particularly perplexing because each of the articles addressed exposure assessment issues, and two of the reports dealt almost exclusively with exposure assessment, monitoring and modeling of exposures, harmonization of exposure assessment methods, mixed exposures from CAFOs, and establishment of monitoring networks for characterization of exposures. Wagstrom's suggestion that we should ignore lagoon breaches or manure pipe ruptures with regard to water quality and focus on daily operations is misguided because these events occur with regularity and lead to significant surface water contamination, fish kills, and loss of recreational use of surface waters.

The report of the Workgroup on Infectious Disease Epidemics and Antibiotic Resistance was given a particularly large task, given that there are > 1,500 scientific papers indexed in PubMed (National Library of Medicine 2007) each year on avian influenza and 230/year on antibiotic resistance in livestock. It was not their task to provide a survey of livestock zoonoses.

Table 1.

Wagstrom also raises questions about the Danish experience after the antibiotic growth promotant (AGP) ban. The facts are that consumption of antibiotics for livestock production in Denmark was > 200 metric tons in 1994, 160 tons in 1997 when antibiotics were last used as growth promotants for weanling and finishing pigs, and dropped to 114 tons in 2005 when this use had ceased (Table 1) [Danish Integrated Antimicrobial Resistance Monitoring and Research Program (DANMAP) 2006]. Pig production increased over this same period from 21 to 26 million hogs (DANMAP 2006). Pig mortality during the last 10 years increased from 6% to 8.2%, with some of the increase attributable to the AGP-ban but much of the increase due to a new viral infectious disease (postweaning multisystemic wasting syndrome) that arose in 2000 (Dahl J, personal communication).

This Mini-Monograph represents current, peer-reviewed science and recommendations developed by leading independent researchers in the field. We welcome further dialog with the National Pork Board and other producer groups so that the United States can achieve needed environmental health improvements in the livestock industry.

The author declares he has no competing financial interests.

References

Bunton B, O'Shaughnessy P, Fitzsimmons S, Gering J, Hoff S, Lyngbye M, et al. 2007. Monitoring and modeling of emissions from concentrated animal feeding operations: overview of methods. Environ Health Perspect 115:303–307; doi:10.1289/ehp.8838 [Online 14 November 2006].

Burkholder J, Libra B, Weyer P, Heathcote S, Kolpin D, Thorne PS, et al. 2007. Impacts of waste from concentrated animal feeding operations on water quality. Environ Health Perspect 115:308–312; doi:10.1289/ehp.8839 [Online 14 November 2006].

Danish Integrated Antimicrobial Resistance Monitoring and Research Program. 2006. DANMAP 2005 - Use of Antimicrobial Agents and Occurrence of Antimicrobial Resistance in Bacteria from Food Animals, Foods and Humans in Denmark. Available: http://www.danmap.org/pdfFiles/Danmap_2005.pdf [accessed 12 2007].

Donham KJ, Wing S, Osterberg D, Flora JL, Hodne C, Thu KM, et al. 2007. Community health and socioeconomic issues surrounding concentrated animal feeding operations. Environ Health Perspect 115:317–320; doi: 10.1289/ehp.8836 [Online 14 November 2006].

Gilchrist MJ, Greko C, Wallinga DB, Beran GW, Riley DG, Thorne PS. 2007. The potential role of concentrated animal feeding operations in infectious disease epidemics and antibiotic resistance. Environ Health Perspect 115:313–316; doi:10.1289/ehp.8837 [Online 14 November 2006].

Heederik D, Sigsgaard T, Thorne PS, Kline JN, Avery R, Bønløkke JH, et al. 2007. Health effects of airborne exposures from concentrated animal feeding operations. Environ Health Perspect 115:298–302; doi: 10.1289/ehp.8835 [Online 14 November 2006]

National Library of Medicine. 2007. PubMed. Available: http://www.ncbi.nlm.nih.gov/sites/entrez?db= pubmed [accesses 7 June 2007].

Thorne PS. 2007. Environmental health impacts of concentrated animal feeding operations: anticipating hazards—searching for solutions. Environ Health Perspect 115:296–297; doi:10.1289/ehp.8831 [Online 14 November 2006].

U.S. Department of Agriculture. 2007. Farms, Land in Farms, and Livestock Operations 2006 Summary. Available: http://usda.mannlib.cornell.edu/usda/current/FarmLandIn/FarmLandIn-02-02-2007.pdf [accessed 12 March 2007].