Background
The U.S. rendering industry collects and safely processes approximately 52 billion pounds of animal by-products and mortalities each year. However, economic conditions brought on by feed restrictions (21 Code of Federal Regulations 589.2000, the “feed rule”) to prevent the spread of bovine spongiform encephalopathy (BSE), and escalating energy costs, have made it necessary for renderers to charge for their services. As a result, the amount of animal by-products and mortalities that are disposed without proper safeguards has increased. For example, the percentage of cattle mortalities processed by rendering decreased from 56 percent in 1995 to 45 percent in 2000.1
The rendering industry agrees that the feed rule has been an important and necessary firewall to prevent the amplification of BSE in the United States. However, with the confirmation of three BSE positive cows in the United States and five positive cows in Canada since the spring of 2003, the Food and Drug Administration (FDA) Center for Veterinary Medicine is considering a complete or partial ban on the use of SRMs and cattle mortalities in feed or food for all livestock, poultry, and pets. If such additional restrictions are enacted, the disposal of such materials must also be regulated to prevent unintended consequences. Unless regulated, control over the collection, transportation, and disposal of these materials would be lost as many farmers, packers, and meat processors seek low cost disposal alternatives. Banning SRMs and cattle mortalities from animal feed would prevent recapturing significant value from such products, making it impractical for rendering companies to collect and process these materials as they do now.
Role of Rendering
The rendering industry provides services for the safe collection of animal by-products and mortalities, transports the materials in biosecure, leak-proof trucks, and uses heat (240 to 290 degrees Fahrenheit, 115 to 145 degrees Celsius) to dehydrate and separate the fat and solid materials. Research has shown that the time and temperature used to process these materials inactivates conventional pathogens and reduces infectivity of the BSE agent by one to three logs (10- to 1,000-fold).2 The rendering process converts raw animal materials into tallow and meat and bone meal, which, unless re-contaminated, are free from pathogenic bacteria, viruses, and other conventional organisms and stable for prolonged storage.
Timely processing, processing temperatures, and the concentration of animal mortalities and other animal tissues at a finite number of locations provides the Animal and Plant Health Inspection Service (APHIS) with many of the necessary tools needed to prevent disease outbreaks, eradicate diseases, and monitor the health status of animal herds and flocks in the United States. It will be difficult for APHIS to realize their mission if the rendering industry is not utilized to its fullest potential.
Disposal Alternatives
As a general rule, the cost of disposing of animal by-products and/or animal mortalities rises in inverse proportion to the environmental impact of the disposal options chosen.3 The cheapest disposal methods, including burial, abandonment, and low-investment composting, are seldom biosecure because the disposal conditions do little to kill or contain pathogens.
Composting: Interest in using on-farm composting for the disposal of animal by-products and mortalities is growing because the practice is perceived to be simple and economical. However, properly designed and managed compost sites are complex, management intense, and require significant capital investments.4 Contrary to popular belief, simply covering mortalities in manure is not true composting. As a result, most attempts at on-farm composting fail because such sites tend to be poorly managed and are not constructed to prevent or contain runoff and protect the environment. Instead of being composted, the materials become piles of rotting tissues and carcasses that offer no more biosecurity than carcasses that have been abandoned.
Burial: Although it is one of the most widely used disposal methods, burial creates the greatest risk to human health and the environment because of the potential for ground and surface water contamination if strict guidelines are not followed.
Landfills: Space is the most apparent limitation to disposing of animal materials in landfills. While rendering and incineration dehydrate the materials to reduce volume, amendments such as sawdust must be added to animal materials before landfilling to accommodate their high water content, which increases volume. Also, some national landfill operators no longer accept unprocessed animal materials that cannot be used in feed.
Incineration: Because of the high temperatures used, incineration is a biologically safe method if done properly in an approved mortality incinerator. However, current incineration capacity is inadequate. Construction of new incinerators requires significant capital investments and is difficult to permit because of air quality issues.
Alkaline digestion: Alkaline digestion is an effective and relatively new technology that uses heat and alkaline conditions to inactivate conventional pathogens. Prolonged exposure to these conditions for six or more hours may also inactivate the BSE agent. However, alkaline digesters have limited capacity, produce large quantities of effluent that must be disposed, and are limited in number.
Rendering: The rendering process provides a means to break the disease cycle. Typical pathogens are destroyed rapidly by processing at lethal temperatures. For other disease agents, such as the prions responsible for causing BSE, the implicated animal by-products may be destroyed or disposed after they have been rendered to verify that the disease cycle has been broken.
Following their experiences with BSE and foot and mouth disease (FMD), the United Kingdom Department of Health evaluated various methods of animal mortality disposal for potential risks to public health.5 Compared with landfills and burial, disposal methods that involved heat processing, such as rendering and incineration, were more effective at controlling biological hazards, including food pathogens (such as E. coli, Listeria, Salmonella, and Campylobacter), organisms that cause diseases (such as anthrax, botulism, leptospirosis, bovine tuberculosis, plague, and tetanus), and surface and ground water pathogens (Cryptosporidium and Giardia). Only rendering minimized the potential health risks to chemical hazards such as dioxins, hydrogen sulfide, as well as emissions of sulfur oxide and nitrogen oxide.
The National Renderers Association believes that appropriate safeguards must be used for the disposal of animal by-products and mortalities in order to protect animal and human health. Regulations requiring animal by-products and mortalities to be heat or chemically processed (such as with rendering, incineration, or alkaline digestion) will certainly reduce animal and human exposure to conventional pathogens, as well as provide some reduction in BSE infectivity, if the infectious agent is present.
In the event that the FDA prohibits SRMs and/or cattle mortalities from animal feed, the rendering industry would have to restructure somewhat to provide dedicated disposal sites for the collection, processing, and disposal of the prohibited materials.3 However, without the development and enforcement of disposal standards to ensure traceability, biosecurity, and environmental protection, animal-based materials that are banned from feed would be diverted from such facilities and be disposed of by the cheapest and least appropriate method available. Even without changes in the feed rule, regulation of dead animal disposal would enhance human, animal, and environmental healths.6
References
1. Sparks Companies, Inc. March 2002. Livestock Mortalities and Their Potential Costs.
2. Taylor, D.M., S.L. Woodgate, and M. J. Atkinson. 1995. Inactivation of the Bovine Spongiform Encephalopathy Agent by Rendering Procedures. Veterinary Record 137:605-610.
3. Informa Economics Inc. (formerly Sparks Companies, Inc). August 2004. An Economic and Environmental Assessment of Eliminating Specified Risk Materials and Cattle Mortalities from Existing Markets.
4. United Kingdom Department for Environment, Food, and Rural Affairs. May 2002. Risk Assessment: Use of Composting and Biogas Treatment to Dispose of Catering Waste Containing Meat.
5. United Kingdom Department of Health. June 2001. A Rapid Qualitative Assessment of Possible Risks to Public Health from Current Foot and Mouth Disposal Options – Main Report.
6. Hamilton, C. Ross, and David Kirstein. August 2002. Animal By-products and Rendering: Biosecure Preservation of Sustainable Animal Agriculture. National Renderers Association presentation to the Food and Drug Administration and U.S. Department of Agriculture.
June 2006 Render