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CHOICE CHOICES The magazine of food, farm, and resource issues 2nd Quarter 2005 • 20(2) CHOICES 103 A publication of the American Agricultural Economics Association 2nd Quarter 2005 • 20(2) ©1999–2005 CHOICES. All rights reserved. Articles may be reproduced or electronically distributed as long as attribution to Choices and the American Agricultural Economics Association is maintained. Choices subscriptions are free and can be obtained through http://www.choicesmagazine.org. The Response to BSE in the United States By John Fox, Brian Coffey, James Mintert, Ted Schroeder, and Luc Valentin Since the emergence of bovine spongiform encephalopathy (BSE) in the United Kingdom in the late 1980s, the United States has implemented various measures to prevent the disease from entering the country, to prevent its spread if discovered here, and to safeguard human health. Regulatory actions included import restrictions, a ban on certain ruminant tissues in ruminant feed, and a surveillance program. Additional measures, aimed at reassuring domestic and foreign consumers about the safety of US beef, were implemented following the December 23, 2003 announcement that a dairy cow in Washington State had tested positive for BSE. In the sections that follow, we discuss the US response to BSE under three broad categories —trade policy, food and feed restrictions, and surveillance. Our analysis focuses on the costs associated with various regulatory actions and less so on potential benefits that are more difficult to quantify. Trade Policy Following the announcement of the first US case, 53 countries, including major markets such as Japan, Mexico, South Korea, and Canada, banned imports of US cattle and beef products. This came as no surprise—automatic border closure following such announcements had become standard procedure. The United States itself blocked imports of Canadian beef and cattle following the announcement of the first Canadian case in May 2003. Border closure in response to a very low BSE incidence in an exporting country is not endorsed by the World Organization for Animal Health (OIE), particularly when control measures are in place. Moreover, although the United States itself had not adhered to OIE guidance on trade, the United States Department of Agriculture (USDA) did initiate regulations to allow imports from countries, specifically Canada, that presented a "minimal risk" of introducing BSE. This minimal risk region (MRR) rule that would reopen the border to imports of Canadian cattle less than 30 months old was to become effective March 7, 2005. However, in response to a motion filed by the Ranchers-Cattlemen Action Legal Fund (R-CALF), a federal court in Montana granted a preliminary injunction blocking the measure. A hearing to determine whether a permanent injunction should be granted is scheduled for July 27, 2005. The controversy surrounding the reopening of the Canadian border illustrates the potential gains and losses from any change in trade policy. Although R-CALF may indeed be concerned about the human health risk from Canadian cattle (though some might doubt it), it is clear that US cattle producers, particularly those in the northwestern US, would lose from import competition in the short run. Marsh, Brester, and Smith (2005) estimate that Canadian imports would reduce US feeder cattle prices by $4.57/cwt. However, in the long run, if adequate cattle supplies are not available locally to keep US packing plants in the region open, producers in the Northwest will lose local cattle markets. Similarly, US producers are losing from the current restrictions on US exports. In 2003, beef exports were valued at $3.95 billion and accounted for 9.6% of US commercial production. Although some important markets, including Mexico and Canada, did partially reopen during 2004, exports for the year were 82% below 2003. Coffey, Mintert, Fox, Schroeder, and Valentin (2005), in an analysis performed for the Kansas Department of Agriculture, suggest that US beef industry losses from export restrictions during 2004 ranged from $3.2 billion to $4.7 billion. The question we might ask here is whether these trade disruptions and associated welfare losses could have been avoided. Caswell and Sparling (in press) emphasize the importance of an internationally coordinated response to managing risks from diseases such as BSE, and Caswell (in press) argues that the potential trade impacts of BSE discovery were not sufficiently weighted in the BSE risk management process. Thus, if MRR legislation had been enacted prior to the recent discoveries of BSE outside of 104 CHOICES 2nd Quarter 2005 • 20(2) Europe, we may never have banned imports of Japanese beef when they discovered their first case in September 2001, nor vice versa. Of course, with the benefit of hindsight, it is easy to point out what might have been. Nevertheless, both Canada and the United States had been warned by the European Union in July 2000 that they were at risk for discovering the disease (Scientific Steering Committee, 2000). Surveillance In 2003, the USDA tested approximately 20,000 cattle for BSE. Countries in which the disease is established have more intensive surveillance —for example, the EU has tested around 8 million head per year since 2001 (Fox & Peterson, 2004). Following the Washington State case, the USDA announced a one-year enhanced surveillance program. The objective was to test as many cattle as possible from high-risk categories— those exhibiting signs of central nervous system disorders, nonambulatory cattle, and those that die on farms—in addition to a random sample of healthy older animals. In various news releases, the USDA stated that a sample size of 268,000 animals would allow for the detection of BSE at a rate of one positive in 10 million adult cattle with a 99% confidence level. That claim, however, is based on the assumption that all cases occur in the targeted high-risk group and that the incidence in nontargeted categories is zero. As of April 2005, 314,000 cattle had been tested under the new protocol with no positive cases identified. Table 1 provides an excerpt from the test results. The surveillance program has been a source of controversy in areas related to testing protocol, announcement of inconclusive results, and an incident in Texas in May 2004 in which an animal exhibiting central nervous system symptoms was not tested for the disease. Inconclusive (or false positive) test results are expected with the Bio-Rad rapid screening test used by USDA. The false positive rate is variously estimated at between one in 50,000 to as little as one in 300,000 tests. Thus far, the USDA has announced three inconclusive results—two in June 2004 and one in November 2004— all of which, upon confirmatory testing using immunohistochemistry (IHC), were found to be negative. The initial announcements of inconclusive cases were controversial and led the Animal and Plant Health Inspection Service (APHIS) to revise their announcement procedure— delaying announcement until a sample produced two inconclusive results with the rapid test. Concern about potential market disruption due to false positives is one reason cited by opponents of wider scale or voluntary testing. For example, following the announcement of the third inconclusive test result on the morning of November 18, 2004, most live cattle futures contracts opened around $2/ cwt lower than the previous day’s close, and many moved limit down that day. Very light sales in the cash market in the following days were likely the short-run cash market reaction to the news. At the same time, there has been speculation that the USDA deliberately chose a test with a relatively high rate of inconclusive results as a means of desensitizing markets to the possible discovery of true positive cases (Mitchell, 2004). Also controversial is the USDA’s choice of IHC as their "gold standard" test. In February 2005, Consumers Union called on the USDA to retest inconclusive samples using the Western Blot test, which, they argued, was more sensitive and more objective. According to the Consumers Union, the Western Blot test is used as the confirmatory test in Japan and Europe and had been used previously by the USDA to confirm the December 2003 Washington State case. (See Pruisner, 2004, for more information on BSE testing.) The future of the surveillance program has not yet been decided. Industry officials have called for it to be scaled back. Not surprisingly, some consumer advocacy groups favor wider scale testing. For example, a March 16, 2005 editorial in The New York Times proposed that "the only responsible way to resume international trade in beef is to ensure the health of the cattle. And the only way to do that is to test the cattle—all of them, if need be." In what turned out to be a particularly thorny issue for the USDA, in July 2004 the agency denied an application by a small Kansas beef processor, Creekstone Farms, for permission to voluntarily test slaughter cattle in an attempt to regain access to the Japanese export market. The beef industry is sharply divided on the issue of voluntary testing. Proponents tend to view it in terms of a marketing decision with expected benefits outweighing costs, at least in the short run. Indeed, our analysis for the Kansas Department of Agriculture (Coffey et al., 2005) suggests a potential net benefit ranging from $27.50 to $48.50 per head (before fixed costs) if voluntary testing restored full access to the Japanese and South Korean markets. Opponents argue that BSE testing is unnecessary and costly, that it sets a dangerous precedent in terms of acquiescing to an unreasonable customer demand, and that it is not scientifically valid and provides no risk- 2nd Quarter 2005 • 20(2) CHOICES 105 reduction benefit to consumers. Large US meat processor stances regarding BSE testing suggest that the investments and logistics of largescale testing, in addition to the potential impact on demand of a positive case, are such that it is a losing proposition for bigger firms—perhaps in particular for those diversified either internationally or across meat products. For a single small firm, on the other hand—especially one more heavily reliant on export sales to high-quality foreign markets than the major packers—the situation is different. If voluntary testing provided export market access, it could produce substantial monopolytype benefits in the short run. Creekstone officials have stated that their increased revenue from regaining access to the Japanese market would far exceed the testing cost of $20 or less per head. Thus, for Creekstone, the private incentive to pursue testing was fairly clear. It is worth noting however, that this scenario would produce no benefit for producers, because increased demand from a single small firm would have a negligible impact on cattle prices. However, if testing did provide market access, more firms would be attracted to testing, and domestic cattle prices would increase. Finally, regarding the current surveillance effort, it is not yet clear how successful the USDA has been in its efforts to sample the targeted highrisk groups. The APHIS website provides no breakdown of samples by animal categories (Table 1), in contrast to the UK, where detailed breakdowns for various risk categories in the active surveillance programs are provided (Table 2). Clearly, no one associated with the US beef industry wants to find this disease. However, the perception that officials may have latitude in terms of sample selection, rumors about animals not sampled, and allegations by at least one former USDA employee about the mishandling of potentially positive test samples, does not help engender confidence among foreign buyers or policy decision makers. Critics have commented that Germany did not begin to find BSE until it allowed private testing. If the disease is truly not present in the US herd, then the industry has little to fear from allowing expanded private testing. However, what are the odds that the surveillance program in place during 2003 managed to detect the only BSE-infected cow in a herd of 100 million? Food and Feed Restrictions In January 2004, the Food Safety Inspection Service (FSIS) banned nonambulatory animals and certain tissues designated as specified risk material (SRM) from the human food supply. The new regulations require firms to age animals using postmortem dentition, to deal with nonambulatory animals, and to segregate SRM material. Using data from a survey of meat processors, Coffey et al. (2005) estimated the Table 1. Excerpts from the USDA’s BSE test results report. Date Negative Inconclusive Inconclusive result Positive Total Week 45 (4/4/05–4/10/05) 9,138 0 — 0 9,138 Week 44 (3/28/05–4/3/05) 10,663 0 — 0 10,663 Week 25 (11/15/04–11/21/04) 7,900 1 Negative 0 7,901 Note. Data from USDA Animal and Plant Health Inspection Service (2005). Table 2. Excerpts from the UK BSE test results report—2005. Ongoing surveys (cattle) Tested Results pending BSE not confirmed BSE confirmed Fallen stock 18,574 3 18,558 13 Casualties on farm 30,825 11 30,788 26 Casualties at OTMS abattoirs 3,165 0 3,164 1 24–30 month casualty cattle at fresh meat abattoirs 211 0 211 0 Over thirty months (OTM) scheme— random animals (born before August 1996) (before feed ban) 2420 0 2417 3 OTM scheme—animals born after July 1997 28,613 0 28,613 0 Animals sampled as 96/97 cohort (excluding fallen stock, casualties, etc.) 26,726 0 26,726 0 Birth cohorts of BSE cases 380 0 380 0 BSE offspring 43 0 43 0 Animals slaughtered for human consumption: OTM (beef assurance scheme) 22 0 22 0 Note. Data from Defra UK (2005). 106 CHOICES 2nd Quarter 2005 • 20(2) additional labor costs of these tasks at approximately $0.45 per head of plant capacity. As currently defined, SRM includes the brain, skull, eyes, trigeminal ganglia, dorsal root ganglia, spinal cord, and vertebral column from cattle 30 months of age and older, and the tonsils and the distal ileum of all cattle. In order to ensure complete removal of the distal ileum, the rules required that the entire small intestine be disposed of as inedible. The small intestine rule has been the most controversial aspect of the SRM regulation because for some firms it was a valuable byproduct, particularly in some export markets. Coffey et al. (2005) estimated that on average, firms that previously sold small intestines were losing from $3.23 to $4.13 per head because of the rule. Other products condemned as a result of BSE regulations include bone-in cuts from overthirty- month (OTM) animals that contain vertebral column (i.e., Tbone steaks) and product obtained from advanced meat recovery (AMR) using OTM vertebral columns. Coffey et al. (2005) estimated that restrictions on bone-in cuts and AMR reduce per-head revenues by approximately $8.50 and $9.36, respectively, on affected OTM animals, while the ban on nonambulatory (downer) cattle resulted in an aggregate loss of approximately $63 million. On February 2, 2004, a panel of experts (the International Review Team or IRT) commissioned by the USDA provided recommendations for future actions for managing BSE risk. With regard to feed regulations, the IRT recommended that (a) unless aggressive surveillance showed BSE risk to be minimal, SRM should include the brains and spinal cords of all animals over 12 months and the entire intestine of all animals; (b) SRM should be excluded from all animal feed including pet food; and (c) all meat and bone meal (MBM), including avian, be excluded from ruminant feed. Earlier, on January 26, the Food and Drug Administration (FDA) announced plans to strengthen the ruminant feed ban that had been in place since 1997. In particular, the FDA said it would eliminate exemptions for bovine blood and plate waste and ban the feeding of poultry litter. In July 2004, the FDA published an Advance Notice of Proposed Rulemaking (ANPR) with an invitation to comment on several aspects of the ruminant feed ban, including the recommendations of the IRT. The comment period for this notice ended on September 13, 2004, but as of April 2005, the FDA had not implemented any of its proposed actions, and the exemptions for plate waste and bovine blood products in the 1997 feed ban remained in place. Additional restrictions on SRM or ruminant feed would hurt the cattle sector by eliminating markets for certain products or increasing feed costs. Ruminant blood meal, for example, is widely used in cattle feed, particularly for dairy cows and in milk replacement rations for calves. When FDA announced plans to eliminate the blood exemption, the values of ruminant and porcine blood meal, which had been similar, diverged. During 2004, ruminant blood meal traded at an average discount of $250 per ton compared to the porcine product. Coffey et al. (2005) estimated that if the blood exemption were eliminated, the value of ruminant blood meal would fall by an additional $225 per ton, resulting in a combined loss of approximately $1.43 for an average steer. Similarly, the cost of banning currently defined SRM from all animal feed was estimated at $2.16 per head, and if the SRM definition were extended (as recommended by the IRT), the cost would be $6.77 per head. If additional cases of BSE are found in the United States, it seems likely that some of the changes proposed by the FDA will become law. The benefits of implementing those measures are more difficult to quantify than their costs. The Harvard/ Tuskegee risk analysis (Cohen et al., 2001) estimated that a ban on SRM in both human and animal feed would reduce the predicted number of BSE cases (in the event it is present) by 80% and the potential human exposure by 95%. However, the baseline level of exposure is so low that further reductions appear to have minimal value. As testing technologies develop and testing costs fall, it may be more efficient to test animals for the disease instead of condemning their products. Testing, even at current prices, appears preferable to a total ban on feeding any ruminant derived proteins to animals —a measure currently in place in the EU and Japan. Coffey et al. (2005) estimated the cost of such a ban at $14.00 per head in lost revenue plus $4.50 per head in additional feed costs. However, for reasons that are not clear to us, the testing option is not currently applied to nonambulatory animals—even in cases in which an animal sustains an injury in transport. Conclusions Although the US response to BSE can be critiqued in some areas, the overall response appears to be far more efficient than, for example, that of Japan, which removed all cattle over 30 months from the food chain, instituted universal BSE testing, and banned meat and bone meal for all 2nd Quarter 2005 • 20(2) CHOICES 107 uses. US policy makers appear to have considered the costs and benefits of various approaches and recognized that the risk to human health is extremely low. How low is the risk? In the United Kingdom, the human version of BSE has claimed around 150 victims. However, they have had more than 180,000 BSE infected cows, most of which were found before the connection to human disease was recognized. Estimates of the total number of animals infected in the United Kingdom run to as high as two million. Had Canadian and US authorities taken no precautions to eliminate SRM tissues from food, four Canadian BSE cases might have led to 0.004 human cases in the next 10–15 years. The human health risk from BSE is probably far lower than the risk of choking on a toothbrush. Thus, to suggest, as did Judge Richard Cebull in granting the injunction blocking imports of Canadian cattle, that BSE poses a "genuine risk of death for US customers" is a complete distortion of the concept of what is really risky. Beef, like any other food, is not and never can be 100% risk free. However, today’s salient risk is not mad cow disease. Instead, it is the more familiar bacterial pathogens like Salmonella and E. coli, the incidences of which have dropped significantly in recent years. By refusing to implement drastic measures in response to a virtually nonexistent threat, policy makers may foster a more rational perception of the risk associated with the disease. Not permitting voluntary testing of young animals, because it provides no useful information for consumers, could well be viewed as part of that strategy. The wider impact of such a measured response may be one of enhancing the overall stability of food demand and making it less responsive to food scares that occur from time to time. For More Information Caswell, J. (in press). A food scare a day: Why aren’t we better at managing dietary risk? Human and Ecological Risk Assessment. Caswell, J., & Sparling, D. (in press). Risk management in the integrated NAFTA market: Lessons from the case of BSE. In Karen Huff (Ed.), Proceedings of the First Annual North American Agrifood Market Integration Workshop. Guelph, Ontario: University of Guelph. Coffey, B., Mintert, J., Fox, J., Schroeder, T., & Valentin, L. (2005). The economic impact of BSE on the US beef industry: Product value losses, regulatory costs, and consumer reactions. (Extension Bulletin MF-2678). Manhattan, KS: Kansas State University Agricultural Experiment Station and Cooperative Extension Service. Cohen, J., Duggar, K., Gray, G., Kreindel, S., Abdelrahman, H., Habtemariam, T., et al. (2001). Evaluation of the potential for bovine spongiform encephalopathy in the United States. Boston, MA: Harvard Center for Risk Analysis. Available on the World Wide Web: http://www.hcra.harvard. edu/pdf/madcow.pdf. Defra UK. (2005). BSE: Statistics - BSE - GB weekly cumulative statistics. London: Defra. Available on the World Wide Web: http:// www.defra.gov.uk/animalh/bse/ statistics/weeklystats.html#act. Fox, J., & Peterson, H. (2004). Risks and implications of bovine spongiform encephalopathy for the United States: Insights from other countries. Food Policy, 29(1), 45-60. Marsh, J., Brester, G., & Smith, V. (2005). The impacts on US cattle prices of re-establishing beef trade relations (Briefing No. 74). Bozeman, MT: Montana State University Agricultural Marketing Policy Center. Mitchell, S. (2004). USDA advised against mad cow test in 2002. United Press International. Available on the World Wide Web: http://www.organicconsumers. org/madcow/test71304.cfm. Pruisner, S. (2004, July). Detecting mad cow disease. Scientific American, 291(1), 86-93. Scientific Steering Committee of the European Union. (2000). Report on the assessment of the geographical BSE-risk (GBR) of the United States of America. Brussels: European Commission. Available on the World Wide Web: http:// europa.eu.int/comm/food/fs/sc/ ssc/outcome_en.html. United States Department of Agriculture Animal and Plant Health Inspection Service. (2005). USDA’s BSE testing: Protecting America’s herd. Washington, DC: United States Department of Agriculture. Available on the World Wide Web: http:// www.aphis.usda.gov/lpa/issues/ bse_testing/test_results.html. Vina, S. (2004). The private testing of mad cow disease: Legal issues (report RL32414). Washington, DC: Congressional Research Service. Available on the World Wide Web: http://www.ncseonline. org/NLE/CRSreports/ 04Jun/RL32414.pdf. John Fox, James Mintert, and Ted Schroeder are professors and Brian Coffey and Luc Valentin are research assistants in the Department of Agricultural Economics at Kansas State University, Manhattan, Kansas. 108 CHOICES 2nd Quarter 2005 • 20(2) http://www.choicesmagazine.org/2005-2/safety/2005-2-03.pdf SEAC Draft Minutes of the 74th meeting held on 13th June 2002 at DEFRA snip... Blood 7.19 The Committee were informed that the inclusion of blood and blood products is banned from animal feed. Under current Animal By-Products Regulations it can be spread on land or incorporated into fertilisers as well as being used in veterinary products. Thus, there was scope for intra-species recycling through these routes. 7.20 The Committee were informed that the new EU Animal By-Products Regulations, which are expected to come into force in early 2003, would place many additional restrictions on the manner in which blood can be disposed. For example, for inclusion in fertilisers, mammalian blood would first have to pass an anti-mortem inspection, then rendered to a pressure cooking standard. Similarly mammalian blood which had passed both ante and post mortem inspections before rendering (although not to pressure cooking standards), could also be used in pet food. However fertilisers containing blood or blood products would not be allowed to be applied on pastureland on which animals graze. Furthermore the mammalian blood would be from animals that were going into the human food chain and as such would be classified as low risk. 7.21 The Committee were content with the position although some concern was expressed over the potential recycling link of sheep blood, which could be distributed on fields containing sugar beet where sheep may graze. snip... http://www.seac.gov.uk/minutes/mins13-06-02.pdf PROPOSED CONSOLIDATION OF THE TRANSMISSIBLE Room 358 scottishTSEregs@scotland.gsi.gov.uk 27 June 2005 Dear Consultee This letter seeks your comments on our proposals to The new A draft Separate consultations on proposals to make similar The Food Standards Agency has been fully involved in the Key Proposals Many of the existing provisions of the We invite your views on a number of issues which have Partial Regulatory Impact Assessment ( The partial We invite your comments on the proposed changes plus any Please send your comments on this paper and attached Your response cannot be made public until the respondee If you have any queries contact Andrew Taylor 0131 244 Martin Morgan signature Yours faithfully http://www.scotland.gov.uk/Publications/2005/06/27105159/52044 SEAC Chair 4 10:45 Early phase of vCJD infection in recipients of blood transfusions Dr Marc Turner (NBS) 87/3 (54 KB) 1 7 First probable case of blood transfusion associated transmission of vCJD 17. In February, SEAC was updated about the Transfusion Medicine Epidemiology Review (TMER) funded by the Department of Health (DH) to examine possible links between vCJD and blood transfusion. In the course of the study, a case of possible transmission of vCJD by blood transfusion had been identified. The recipient received blood in 1996 from a donor who, at the time of donation, was free of clinical signs of vCJD, although went on to develop vCJD in 1999. The blood recipient died of vCJD in 2003. Although the possibility could not be ruled out that the blood recipient was infected as a consequence of consuming meat products contaminated with the BSE agent, statistical analysis suggested that it was unlikely that the association between the blood recipient and the blood donor was due to chance. 18. SEAC agreed that the case raised the possibility that the infection may have been transmitted by the blood transfusion. However, it was SEAC Annual Report 2004 noted that this was a single case. The recipient had received blood before leucodepletion of blood donations had been adopted in the UK in 1998, as a precautionary measure. The measure was introduced as it was considered that leucodepletion of blood would significantly reduce the risk of blood transfusion associated transmission of vCJD. SEAC noted the importance of the TMER in identifying potential transfusion associated vCJD cases. SNIP... 10 Second probable case of blood transfusion associated transmission of the vCJD agent 27. In June, DH asked the committee to advise on the public health implications of a second probable case of blood transfusion associated transmission of the vCJD agent. The patient who died in 2004, from a cause unrelated to vCJD, showing no clinical signs of vCJD, had received a single unit of blood in 1999. This blood was donated by an individual who subsequently developed vCJD in 2000 and died in 2001. Post mortem findings in the blood transfusion recipient suggested a possible preclinical case of iatrogenic vCJD associated with blood transfusion. However, the patient resided in the UK, and oral exposure to the BSE infectious agent could not be excluded as a possible cause of infection. 28. On the basis of a statistical analysis of the possible causes of infection, the committee agreed that the case was much more likely to be attributable to blood transfusion, than food borne infection. The report strengthened the evidence for the transmission of vCJD via blood. However, the committee noted that in this instance, although vCJD infection appeared to have been transmitted, it was not known if clinical vCJD would have developed if the patient had lived longer. SEAC Annual Report 2004 29. The committee agreed that the new case strengthened its opinion, first stated in October 1997, that human blood from persons incubating vCJD may be infective. Additionally, it was a public health priority for all recipients of blood transfusions from donors incubating vCJD to be subject to post mortem investigation, to help quantify the nature and magnitude of the risks of transmission of vCJD via blood. A statement summarising the committee’s consideration of the case is given at Annex 7. snip... Atypical BSE cases 55. In February, SEAC considered the findings of a research paper (Casalone et al. 2004)6 suggesting that a second bovine amyloidotic spongiform encephalopathy had been identified with a molecular signature similar to that of a subtype of sCJD. The committee agreed that the results were very interesting, but without information on the transmissibility of the disease in bioassays, it was premature at this stage to conclude it was a new strain of BSE. SEAC agreed it would follow further research on these samples with interest. http://www.seac.gov.uk/publicats/annualreport2004.pdf - - 16 ITEM 3 – USE OF CATEGORY 3 ANIMAL BY-PRODUCTS IN FERTILISER (SEAC 87/4) - - 17 54. Mr Steve Wyllie (Defra) provided the background to the issue. In 1996 the use of MMBM in fertiliser for agricultural land was banned to cut off potential routes of TSE exposure to livestock. In 2002, EU legislation was introduced that classified animal by-products (ABP) into Category 1 (high risk material from animals with suspected or confirmed TSE), Category 2 (condemned meat from diseased animals) and Category 3 material (fit for human consumption). Category 2 and 3 material was permitted to be used as fertiliser, but in the case of all Category 2 material, and Category 3 material of mammalian origin, only if reduced to a particle size <50 mm and pressure cooked (>133ºC and 3 bar for 20 minutes). In addition, category 3 material could be used in compost if reduced to <12 mm and heated to 70ºC for at least one hour. Appropriately-treated Category 2 and 3 ABP could be applied to non-pasture land. Non-pasture land included a period when farmed animals cannot graze. A three week non-grazing period is currently being proposed by the Commission, based on an EFSA opinion. 55. Mr Wyllie explained that, in contrast to the EU regulations, no rendered MMBM is allowed in fertiliser spread on any agricultural land under current UK regulations. An anomaly also exists within UK legislation as category 3 ABP can be treated in a biogas or composting plant and applied to land. However, if it is treated in a rendering plant it is designated as MMBM and cannot be applied to agricultural land even though it is treated under more severe conditions than it would in a composting/biogas plant. Defra is considering amending the UK legislation to address the anomalies and align UK with EU regulations. As an initial step, Defra commissioned VLA to conduct a release assessment (RA) to estimate the TSE-related risks associated with the use of rendered Category 3 ABP as fertiliser on non-pastureland. 56. Dr Amie Adkin (VLA) presented the methods, inputs and assumptions made in the RA together with the results. The RA considered scenarios of scrapie in sheep, theoretical BSE in sheep, and BSE in cattle, under current conditions, and assessed the impact of removal of the OTM Rule. The RA consisted of four successive modules: Farm Module 57. The farm module estimated the numbers of cattle and sheep within the last 12 months of incubation of scrapie or BSE, that are slaughtered for human consumption per year. It was assumed that BSE is present in the national sheep flock and the prevalence of - - 18 BSE or scrapie is not stratified by age, a lamb having the same probability of being infected in the national flock as an adult sheep. Slaughter Module 58. Using data from the farm module, the slaughter module estimated the quantity of infectious material (expressed as oral ID50), passed as fit for human consumption, leaving slaughterhouses per year. For BSE in cattle it was assumed there was no risk associated with liver, kidney, lung, stomach, blood and trimmings. It was also assumed that animals are fully infected and that carcass contamination of the food chain could occur via four routes: insufficient removal of spinal cord, spinal cord contamination from splitting the carcass, brain tissue from the captive bolt used in slaughter, and the presence of DRG. 59. For the scrapie and BSE in sheep models it was assumed that positive animals were fully infected, the infectivity for BSE in sheep is the same as scrapie, and that carcass contamination of the food chain could occur via two routes: insufficient removal of spinal cord and via infectious tissues not designated as SRM. Rendering module 60. Using the information from the slaughter module, the rendering module estimated the concentration of infectivity in fertiliser (oral ID50 per kg). It was assumed that all TSE infectivity remaining on the carcass after SRM controls subsequently enters category 3 waste. This was a pessimistic assumption as other routes such as landfill, composting or ingestion which would reduce infectivity levels were not included. It was assumed that 50-75% of Category 3 MMBM would be used in fertiliser production. Land module 61. The land module estimated the infectivity of TSE on non-pasture land three weeks post application (oral ID50 per m3) on the basis of the estimates from the rendering module. It was assumed there was no decay of TSE in soil, no leaching of TSE beyond 1 cm of topsoil, and that the yearly input of fertiliser to land is applied in one dose. 62. Dr Adkin explained that the final results of the study related to infectivity in soil available per year, not the probability that a cow becomes infected. The exposure of cattle to that infectivity was outside the scope of the RA. Information on the frequency of cattle - - 19 on non-pasture land, the length of stay and consumption of soil and vegetation would be required for an exposure assessment. The final results from the land module were (with 5th and 95 percentiles): • The average TSE infectivity on non-pasture land per year from cattle with BSE would be 2.0 x 10-11 bovine oral ID50 per m3 (1.7 x 10-12, 6.1 x 10-11) • The average TSE infectivity on non-pasture land per year from sheep with BSE would be 5.0 x 10-9 ovine oral ID50 per m3 (1.3 x 10-10, 1.8 x 10-8) • The average TSE infectivity on non-pasture land per year from sheep with scrapie would be 2.4 x 10-6 ovine oral ID50 per m3 (3.9 x 10-7, 5.8 x 10-6), 500-fold greater than for BSE in sheep. 63. Dr Adkin indicated that the model was sensitive to the amount of MMBM fertiliser applied annually, the effect of rendering on TSE infectivity, the titre of TSE infectivity in tissues and, in the scrapie model, the proportion of natural scrapie that is BSE. Removal of the Over Thirty Month Scheme (OTMS) would increase BSE infectivity 60-fold but infectivity levels would still be extremely low. A worst case scenario had been modelled assuming a fully infected entire BSE carcass including SRM was rendered into one batch of fertiliser (a one in a million million occurrence). In this case, the BSE infectivity on non-pasture land would increase by 6 orders of magnitude from a mean estimate of 2.0 x 10-11 bovine oral ID50 per m3 to a mean of 5.0 x 10-5 bovine oral ID50 per m3. 64. In opening the discussion, the Chair indicated that the RA had been sent to an independent epidemiologist Professor Dirk Pfeiffer (Royal Veterinary College, London) for review. Professor Pfeiffer concluded the RA was logically structured and the data and assumptions clearly described. The results had been presented with due consideration of the assumptions. He noted that the processes used in developing the model, obtaining the data and scrutinising the model were not documented. It was unclear whether the quality of unpublished and published data was scrutinised or taken at face value. In summary, the model structure was appropriate and the conclusions plausible. Improved documentation would enhance the credibility and transparency of the model outputs. 65. A member had also reviewed the RA in detail and concurred that the RA was thoroughly carried out. It was noted that, with the OTMS, the RA had assumed an infectivity level leaving the slaughterhouse of 140 bovine oral ID50 per year whereas other risk - - 20 assessments had used lower values. Dr Adkin commented that the difference was due to inclusion of a fully infected carcase, rather than considering carcases at different points in the incubation period. In addition, the model contained different routes of contamination of the carcase post SRM controls that are not included in other assessments. It was suggested that the assumption of all infectivity remaining on a carcass entering category 3 waste and being spread as fertiliser was perhaps overly pessimistic. 66. Dr Adkin was asked why no uncertainty estimate had been included regarding the OTMS removal scenario. Dr Adkin indicated that the estimates for the number of infected cattle to slaughter were based on a peer-reviewed back-calculation model from Arnold and Wilesmith (2003)2. The model had not been set up to provide the 5th and 95th percentiles in the case of OTMS removal. This had now been explored and the overall results had not changed significantly as a result of including the uncertainty estimate. Dr Matthews added that a previous qualitative risk assessment indicated the risk was very low, and he felt the correct approach for a quantitative RA was to use pessimistic assumptions. There were many uncertainties in terms of the process once material left the abattoir, regarding rendering plant used, volumes of waste and how this material would be used subsequently, therefore estimates had been based on consultation with industry representatives, and if estimated infectivity levels remained low even with pessimistic assumptions this could be considered reassuring. 67. A member noted that the assumptions in the RA were dependent on effective enforcement. It was suggested that a 3 week nongrazing period could be difficult to enforce. In addition, it had been assumed that no imported MMBM was used in fertiliser. Enforcement should be considered in developing policy. 68. It was noted that even distribution of infectivity in fertiliser, and its even distribution across land had been assumed. In reality, TSE infectivity spread would be heterogeneous. Dr Adkin explained that this scenario had been addressed to some extent by the worst case scenario in which a fully infected entire BSE carcass was rendered into one batch of fertiliser. 69. Dr Adkin added that it had been assumed that there was no degradation of prion protein during the assumed 3 week non- 2 Arnold M. and Wilesmith J.W. (2003) Modelling studies on BSE occurrence to assist in the review of the over thirty months rule in Great Britain. Proc Roy Soc Lond B 270, 2141-2145 - - 21 grazing period. Members considered that should TSE agents persist in soil, infectivity could accumulate over time. Dr Adkin indicated that the accumulation of infectivity over time was not addressed, as an exposure assessment had not been carried out. In order for such accumulation to occur TSE infectivity would have to be applied on multiple occasions to the same location, which may be unlikely. One study indicated there would be 98% decay of the agent over 3 years3. Dr Matthews observed that accumulation would be against a backdrop of decreasing TSE prevalence. Mr Wyllie added that Defra- and EU-funded research is being conducted to investigate the behaviour and degradation of TSE agents in soil. 70. A member considered that, since the TSE agent is a protein, it was likely to decay quickly due to the pH of, and bacteria present in, soil. However, a member pointed out good evidence suggesting that the Chronic Wasting Disease agent persisted in the environment. Dr Matthews informed members that a VLA project on infectivity in sheep exposed to the farm environment indicated that material on pasture is infectious for at least 2 months. Members agreed that in view of the resistance of PrPsc to degradation, evidence from CWD and the VLA studies, it was safer to assume survival of the agent in soil for a significant amount of time. 71. In response to members’ questions about the field spreading of fertiliser, Alan Brewer (Defra) informed the committee that some dust can arise from the activity, both from the fertiliser distribution process (that depends on the type of spreading mechanism) and from tractor wheels kicking up soil in arable situations. But it was not possible to indicate whether there was any likelihood of dust particles containing fertiliser drifting onto adjoining fields. He added that it was recognised as good practice for farmers not to spread fertiliser into hedges and watercourses. 72. Members asked whether cross-contamination between category 2 and category 3 material could occur on processing. Mr Wyllie indicated that Category 2 and Category 3 materials had to be rendered in separate buildings, although these could be on the same site. 73. Members asked if the final result of the RA could be an overestimate of scrapie infectivity due to the assumption that all sheep were adults. Dr Adkin indicated this may be a pessimistic 3 Brown P. and Gajdusek D.C. (1991) Survival of scrapie virus after 3 years’ interment. Lancet 337, 269-270 - - 22 assumption as adult sheep have larger tissue sizes. Dr Matthews commented that genotyping studies from the abattoir survey indicated there is a high prevalence of arginine-carrying sheep at codon 171 and that therefore infectivity was more likely to be restricted to the central nervous system rather than other tissues and the RA had assumed the worst case. 74. Members noted that infectivity in fertiliser has the potential for intraspecies recycling and poses a different risk from dead-end infections. It was recommended that surveillance was essential to detect infected animals and identify such a cycle. 75. It was noted that multiple risk assessments tended to consider single routes but often routes were cross-linked. It was suggested that consideration should be given to risk assessments that consider such links rather than specific routes in isolation. Members asked whether risk assessments could be produced in a consistent way and asked if there was a forum to discuss inputs to risk assessments. Dr Matthews indicated that a "Neuroprion Risk Assessment" group was looking to peer review data and generate a consensus for risk assessments. Dr Adkin indicated within the EU, risk analysts are reviewing parameters to enable comparison of models. 76. In summary, the committee concluded: • it was content with the approach used and assumptions made in the risk assessment. • the assessment predicted that TSE infectivity levels on land as a result of the application of fertiliser would be extremely low. However, because of the likely heterogeneous nature of infectivity in fertiliser and the uneven spread of fertiliser, TSE infectivity levels might be higher in some geographical locations than predicted. • controls to ensure that category 3 material is processed separately from Category 1 and Category 2 material be audited. • a watching brief be kept on CWD and BARB cases to assess the possible persistence of the agent in the environment. ITEM 4 – AOB snip... http://www.seac.gov.uk/minutes/final87.pdf Statement -------------------------------------------------------------------------------- Recommendations on the handling of waste material from cattle http://www.seac.gov.uk/statements/state07jun96.htm WE MUST BAN THE SPREADING OF RUMINANT/MAMMALIAN BLOOD ON LAND AND IN FEED FOR ANIMALS THAT HUMANS AND ANIMALS FEED ON...TSS
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