The confirmation of bovine spongiform encephalopathy (BSE), commonly called “mad cow disease,” in the United Kingdom (UK) in 1986 validated the theory that the genesis or random outbreaks of diseases are most often unanticipated and unforeseen, and that the emergence and spread of new infectious diseases will likely continue to threaten both animal and human health in the future. That is a logical assumption based on the his-torical record of infectious diseases.
The evidence in this particular initial BSE outbreak indicates that while we may want to believe that the disease happened only to “them,” and that we are outside the realm of medical history rather than enmeshed within it, the reality appears that we are all in it together, regardless of the risk differentials of countries. I have stated repeatedly over the years that in the era of globalization, a disease incident anywhere, becomes a disease incident everywhere. This is especially relevant for the complex group of diseases we collectively term the transmissible spongiform encephalopathies (TSEs) because of the affirmed public health pertinence of two members of the group, BSE in cattle and the diagnosis of variant Creutzfeldt-Jakob disease (v-CJD) in 1996 in an unusual cohort/cluster in the UK linked to BSE, and the subsequent emergence of the existing epidemic in the UK today.
BSE and the Rendering Inference
Until the advent of BSE in the UK, the rendering industry globally operated on the premise of relative safety assurance based on a historical record of producing feed ingredients that are safe. This all changed in 1988 based on the epidemiological hypothesis that meat and bone meal of ruminant origin was the most likely cause of transmitting the disease. This linkage of an animal protein that has been used as a nutritional supplement in livestock rations for at least a century to a hitherto new disease syndrome created initial alarm and anxiety within the UK with concurrent reverberations throughout the agricultural and livestock communities internationally that exist to this day, approximately 16 years since the confirmatory diagnosis of the first two reported cases at the Central Veterinary Laboratory, Weybridge, UK.
The rendering industry, therefore, became an inherent part of a disease equation and was faced with the greatest challenge in the history of the industry because of BSE and the human health analogy. This forced the industry into a defensive posture with a mandate to assess all aspects of risk while examining the options for future market accommodation of rendered products linked to the disease.
While there were myriads of theories, suppositional anecdotes, and other contributing postulates associated with the transmission of BSE in the UK through the vehicle of feed ingredients of ruminant origin, especially implicating sheep affected with scrapie, a validated finite causal linkage remains hypothetical. In essence, also, from a practical disease control perspective, it made no difference what really contributed to the initial outbreak because the primary pressing demands of preventive controls were more important than retrospection and an examination of the whys of an outbreak.
The prion theory concept is still debated in scientific fora in spite of the compelling research evidence that it is the most likely infectious agent associated with TSEs. In the interim, hypotheses could prevail, but risk analysis and prevention and control strategies have become the predominant objectives throughout Europe and in many other countries with no evidence of the disease.
Risk Analysis
Risk is nothing more than the probability of an adverse outcome. Risk analysis is the structure for making rational decisions in the face of uncertainty and has four distinct elements: hazard identification – what can go wrong and how would it happen; risk assessment – how likely will things go wrong and what are the consequences; risk management – how can we reduce the likelihood or minimize the impact; and risk communication – how can we involve and prepare all those potentially affected.
In the analysis of risk of BSE occurring in a given country, an evaluation must be made of why did the disease occur at a specified period in time, in a distinct geographic region of the globe, and as an entirely new disease entity. These inferences are challenging and provide an insightful introduction to the complex issues faced by the disease investigators and the decision makers in the UK from the onset. Most likely, we may never fully agree on the genesis of BSE, except that it originated in the UK.
Every logical theory and potential contributing cause was thoroughly examined and the resultant hypothesis that appeared most consistent was the feeding of meat and bone meal, most likely consisting of sheep raw material that was infected with scrapie and subsequently not inactivated by the rendering process, thus permitting the infectious agent, presumably a prion, to cross the species barrier and infect cattle through feed in the UK.
This compelling epidemiological evidence, however, only affirms the pertinence of relative risk and the concurrent significance of the regionalization of diseases, because 99.4 percent of all reported cases are in the UK and the other 0.6 percent had suppositional origination in the UK.
Risk, Policy, and Global Inferences
Specified risk material and the use of “dead stock”
Product safety must be based on sound and verified science and there is no valid reason for countries free of BSE that have been processing “dead stock” for over a century should in any way modify policy to terminate the practice of rendering “dead stock,” nor should same countries take the additional precautions for specified risk material, if indeed epidemiological evaluations/risk assessments conducted by the regulatory authorities indicate freedom of disease. In essence, risk of BSE transmission lacks equivalence based on current knowledge and does not necessitate a unified or uniform global policy for all to conform.
Companies may elect to pursue their own policies for trading and commercial advantages, but government instituted directives must be based on scientific affirmation and the analysis of risk.
The World Health Organization (WHO) heightened the interest of global public health and v-CJD prevention by recommending that all countries should ban the use of ruminant tissue in ruminant feed to ultimately minimize the risk of exposure to BSE, and likely v-CJD. Most industrialized countries of the world have accepted this recommendation by instituting appropriate regulatory controls through feeding prohibitions.
Genetically modified organisms
All foods are genetically modified through breeding. Genetically modified organisms (GMOs) are only different because they are produced by using molecular biology techniques. Before a GMO is released into the environment, the product must pass a bio-safety assessment, and are generally only given a release if they are safe and beneficial.
The benefits can be summarized as both environmental and food and farming and include: enhanced environmental quality through less use of chemicals; enhanced natural resources; healthy, cheaper foods; economic development of emerging and small-scale farmers; and easier, safer, and cost-effective farming.
There are certain interest groups that are taking an anti-GM stance to protect their markets, for example the organic farmers. Also, environmental groups who believe, devoid of proof, that this technology is a threat to nature, even though these processes take place in nature all the time, including the fact that traditional plant breeding has been moving genes around in crops for centuries.
Europe, in its quest to be protective, questions GMOs mainly to insure that the food produced within its borders is not under threat by cheaper, better, and more diversified quality foods. To accomplish this, the European Union (EU) has imposed legislation for labeling GM foods and products derived from GM raw materials, regardless of the historical safety of GMOs.
Major concerns of the opponents of GMOs are: the possibility of introducing allergenic proteins into foods; possible increased resistance to antibiotics due to the use of antibiotic gene markers to gauge the success of a gene transfer; “gene-jumping” or the transfer of altered material to humans or other species; and the possible evolution of weeds and pests that are ultra-resistant to herbicides and pesticides.
Dissolved air flotation/sludge/skimmings/biosolids/secondary protein nutrients
This is material skimmed off following pH adjustments and the use of flocculants such as aluminum sulfate to reduce the biological oxygen demand, nitrogen, and phosphorus, and is a common chemical and physical alternative to pre-treating wastewater. Unfortunately, the use and/or disposal of this material remains controversial in spite of its high fat content of about 15 percent and protein (fat free dry matter basis) varying from 40 percent from cattle processing to as much as 70 percent for poultry slaughter/processing.
An EU policy statement says, “the recovery of animal feed materials from process waters in slaughterhouses and other food or feed industry plants is made subject to detailed hygiene measures.” This should be clearly differentiated from sewage sludge that will include wastes from urban, domestic, and industrial wastewater treatment plants which is prohibited in feedstuffs.
The challenge for the rendering industry remains what measures should be taken to ensure hygiene and compliance for inclusion in feed rations of a by-product of the industry that appears to have nutritional value and applicability.
Dioxin
Dioxin remains an active part of the risk policy debate in the United States and obviously has global implications. The inference of the chemical’s carcinogenicity and thus a public health control consideration has been an ongoing discussion within the U.S. Environmental Protection Agency for over a decade.
Dioxin is nonetheless a natural by-product of combustion, generated by the elements of life and living – motor vehicles, wood stoves, medical waste incinerators, garbage burning, and even cigarettes.
Since combustion is an inherent part of the global ecosystem, dioxins, therefore, are found everywhere, and just about everyone carries minute amounts of dioxin in their body fat. Dioxin, then, is just another toxic component of natural origin that must be considered in context. Public emotions must be addressed, but should not rule reason or the science of risk analysis.
The finite law of toxicology is “the dose is the poison,” which basically means that the toxic potential of any substance is proportional to the amount of the substance to which an “organism” is exposed.
The stringent emission laws in most of the industrialized world would indicate that dioxin has been on the decline as a public health threat.
Antibiotic resistance
The intensive animal industry has been blamed for years for increased antibiotic resistance in humans. The subject, however, remains contentious and complex, without ready answers or solutions.
Historically, the use of sub-therapeutic levels of antibiotics in swine and poultry rations as growth promoters has come under scrutiny as potentially contributing to the resistance factors in humans. The debate is not simple. In reality, it has been ongoing for many years with no clear indication that the use of antibiotics in animals is definitely associated with antibiotic resistance in humans.
The National Research Council indicated in a report that, “it is difficult to determine the relative contributions made by sub-therapeutic and therapeutic levels of anti-microbials in animals or in humans to the pool of resistant bacteria that may affect human health.”
The emergence of foodborne diseases as a major global problem continues, nonetheless, to raise the specter of antibiotic use in animals and subsequent resistance in humans, and the suggestion that there must be an inter-relationship, albeit, yet to be fully validated scientifically.
Microbial agents
The rendering processes (time – temperature) are known to inactivate bacteria, viruses, and other pathogens. It is also possible that even though there are apparent limits to what impact rendering processes have on prions, it must be assumed that there are varying levels of inactivation or degrees of decreased infectivity. In essence, the entire subject of prion inactivation is in need of extensive research under plant processing conditions to assess different rendering systems instead of laboratory simulations and extrapolations.
Some of the existing anecdotes about prion resistance only confuse the issue and create “myths” that are not relevant, and only damage the image of the industry. Thus, the need for further inactivation research to modify the current uncertainty.
The rendering industry globally must consider and agree on an indicator organism that can be used as a uniform standard for assessing sanitation and hygiene that can be used as an international code for feed ingredients. I recommend Salmonella as the most considerate option.
In Closing
The advent and subsequent spread of BSE throughout most of Europe focused “microscopic” attention to the rendering industry globally and concerns about the safety of animal proteins as feed ingredients. The issues circumvented the science, for the most part, and became a segment of fear, uncertainty, and anxiety, emotionalized by the media and highlighted by misinformation. In essence, true and relative risk was taken out of context and the concerted efforts of prevention and control were ignored or not heightened in the reporting of the news. Additionally, the human health inferences of v-CJD amplified the entire subject, and livestock agriculture and related ancillaries, including the rendering industry, became “risk factors,” putting meat safety and rendered animal proteins on a revolving stage of negatives.
The challenges to the industry could result in opportunities to pursue a new approach for safety assurance by instituting globally the principles of Hazard Analysis and Critical Control Points as the uniform model for compliance. This initiative would put the industry in a leadership role in the food safety cycle internationally, and could establish and introduce the guidelines needed to unify all sectors to work collectively and with resolve as a “community” to put rendered products back into full usage, based on risk analysis, science, and preventive controls that are germane.
The aforementioned can be accomplished if the industry’s commitment is focused and dedicated to the production of animal protein and fats as an integral part of animal agriculture, environmental health, the food chain, and, indeed, the public health.
Tech Topics - October 2001 Render