Growers and Grocers

Concentrated animal feeding operations (CAFOs) are what can happen when efficiency and cost are the only considerations in food production. Cramming multitudes of animals into close quarters, they create vast amounts of waste, an oppressive stench, plumes of air pollution, inhumane conditions, and additional health hazards or nuisances. As an example, consider a 1998 report from the U.S. EPA (PDF) which said “Animal manure is much more abundant than human waste. It is estimated that in 1992, approximately 133 million dry tons of animal manure were produced, compared to 10 million dry tons of human sanitary waste (See Appendix A). Yet while the disposal of human waste is highly regulated, the disposal of animal waste has been largely unregulated.”

The CAFO is a relatively recent phenomenon, and so scientific understanding of their health impacts is still evolving. In March 2004, a group of scientists and health experts gathered in Iowa City for a conference entitled “Environmental Health Impacts of CAFOs: Anticipating Hazards – Searching for Solutions.” The conference participants produced several summary reports about the state of scientific knowledge about health impacts from CAFOs, with topics that included water quality, antibiotic resistant pathogens, and monitoring methods. The peer-reviewed journal Environmental Health Perspectives published the conference reports in the February issue of the journal. The full content of Environmental Health Perspectives is available on-line for free.
Here is the abstract of the summary article, which describes the conference:

A scientific conference and workshop was held in March 2004 that brought together environmental scientists from North America and Europe to address major environmental health issues associated with concentrated animal feeding operations (CAFOs), which are large, industrialized livestock production facilities. After one and a half days of plenary sessions, five expert workgroups convened to consider the most relevant research areas including: respiratory health effects; modeling and monitoring of air toxics; water quality issues; influenza pandemics and antibiotic resistance; and community health and socioeconomic issues. The Workgroup Reports that follow outline the state of the science and public health concerns relating to livestock production as they apply to each workgroup topic. The reports also identify areas where further research is needed and suggest opportunities to translate science to policy initiatives that would effect improvements in public and environmental health. Viable solutions to some of the current environmental health problems associated with CAFOs are outlined. In addition, these reports bring to light several major concerns, including air and water contamination, the rise of antibiotic-resistant bacteria in livestock and the specter of influenza outbreaks arising from siting industrialized poultry and swine production in close proximity to each other and to humans.

The following Workgroup Reports were produced:

• Health Effects of Airborne Exposures from Concentrated Animal Feeding Operations
• The Potential Role of CAFOs in Infectious Disease Epidemics and Antibiotic Resistance
• Monitoring and Modeling of Emissions from CAFOs: Overview of Methods
• Community Health and Socioeconomic Issues Surrounding CAFOs
• Impacts of Waste from Concentrated Animal Feeding Operations on Water Quality

Some sections of the papers can be rough going, with sentences like this: “This raises methodologic issues regarding appropriate comparison populations and confounders or effect-modifying variables that need to be included in multiple regression models to make accurate comparisons,” or “The inflammatory reactions are orchestrated by alveolar macrophages that carry specific endotoxin binding receptors [LPS binding protein, CD14, MD2, toll-like receptor (TLR) 4]” (both quotes are from Health Effects…). Nonetheless, the papers give a good overview of the current state of knowledge, as well as long reference lists for further investigation. The priority research needs sections are certainly worth reading to get a sense of what the experts want to know.

I found the section about odor in the Monitoring and Modeling… paper to be quite interesting:

The quantification of odor is more challenging because it represents a varying complex mixture of free and particle-bound compounds. An ideal approach to odor measurement would begin by characterizing the chemical constituents associated with a particular offensive odor. Odors could then be quantified objectively based on the identification and quantification of the speciated constituents. However, the correlation between human response and specific compounds identified by instrumental methods such as gas chromatography remains quite poor (Powers et al. 2000). One possible explanation is that the human nose may be sensitive to concentrations that lie below instrumental detection limits. Also, the simultaneous instrumental determination of more than 200 compounds that have been identified in livestock odors is difficult because different groups of compounds require different types of [gas chormatography] columns for efficient separation as well as different operating parameters and detectors. Currently, existing limitations of instrumental methods make the human observer a necessary part of the odor measurement methods. Livestock odor measurement techniques currently rely on trained human raters for odor quantification.

One can imagine the cocktail party conversations of an odor rater: “So, what do you do?” “I walk around feedlots and sniff, then give it a rating, sort of like in figure skating at the Olympics.”

Photo credit: Turkey photo from the UDSA ARS Photo Library.