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From: TSS ()
WHO REGULATES CARCASS COMPOSTING IN ILLINOIS? The Illinois Department of Agriculture Bureau of Animal Welfare is the regulatory authority for composting carcasses, and for the Dead Animal Disposal Act in general. Illinois EPA and Illinois Department of Public Health may become involved in investigating complaints about composters. DO I HAVE TO REGISTER MY COMPOSTING SITE WITH THE DEPARTMENT? Composter site registration is not required at this time. WHERE CAN I SET UP MY COMPOSTING SITE? The site must be located at least ¼ mile from your nearest neighbor’s residence and it must be placed on a suitable location with adequate diversions to prevent surface water from draining to the compost pile. Avoiding water from entering the pile is important in order to give the producer the control over the moisture content of the compost pile. Also, it is essential to keep composter contents from leaching to groundwater or running off to surface water. WHAT TYPE OF A COMPOST FACILITY CAN I CONSTRUCT? MUST IT BE A ROOFED CLOSED-IN FACILITY? A concrete slab with treated lumber bin walls and a roof is preferable. Roofing provides the producer with more control to regulate the amount of moisture during both wet and dry weather, which is important for proper composting. Also the solid flooring and surrounding area allows for easy access to turn the pile or for adding materials to the pile during wet, muddy conditions. The facility could also be as simple as setting large round hay bales end to end on a solid limestone or geotextile base making three-sided rectangular bins. The bale compost setup is not recommended as a permanent installation. You need at least two composting bins, one primary and one secondary. The best way to get the carcass compost to reheat and finish composting is to move the pile over into another bin. HOW BIG SHOULD MY COMPOSTER BE? The size depends entirely on the amount of mortality you expect per year. The minimum bin size for a single cow carcass is about 10 feet square and walls five feet high (double it because you need two bins). WHAT TYPE OF ORGANIC MATTER CAN I USE TO SUPPLY THE CARBON SOURCE NEEDED? Sawmill sawdust is best because of the fine particles that can fill-in around the carcass. Mixture of finely chipped wood, chopped corn cobs, straw, and/or chopped corn stalks will work. The material must be absorbent, maintain its structure to allow the pile to “breathe”, and be a good carbon source for the composting organisms. Wheat straw by itself is not good, as it packs down too tightly. Whole corncobs have too little surface area and need to be chopped or ground. Up to 50 percent of the finished compost can be recycled back to the primary bin. Experience with composting other animal species shows that you will need a ratio of about 3.7 cubic yards of sawdust per 1000 pounds of carcass composted. You should keep a good supply of carbon source on hand, and you may need to keep it covered so you can control the moisture content. WHAT OTHER ITEMS DO I NEED? A compost thermometer with a 36 inch stem is vital for monitoring temperatures and is required by the regulation. You will need a method to get water to the composter to maintain the right moisture. A bucket loader for turning the compost after the first “heat” cycle and for loading out the finished compost is also essential for managing the operation. WHAT IS THE COMPOSTING PROCEDURE FOR PROPER DECOMPOSITION OF ANIMAL CARCASSES? Two composting cycles are needed to complete the decomposition. The carcass may need to be prepared or “processed” to allow for maximum exposure to air, moisture, nutrients and carbon. Animals weighing more than 300 pounds compost faster with some processing including slicing the large muscle areas and opening the thoracic and abdominal cavity. Lancing the rumen will reduce tendency of the carcass to bloat, may reduce odor problems, and it will make it easier to keep the carcass covered with carbon source. The carcass provides the nitrogen source and some moisture, while you will add the carbon source. The moisture content of the compost is important and should be maintained at 40 to 60 percent. Prepare the pile with at least 12 inches of sawdust or other carbon source on the base followed by placing the animal on the sawdust. Large animals should be laid with the backbone down. The animal carcass must be covered totally with at least 12 inches of sawdust or other adequate carbon source (more is better). You will need to add carbon source material to the pile periodically as the carcass breaks down (check the composter as part of your daily routine). Monitor the temperature of the pile using the 36” thermometer, and record the temperatures and date. Composting temperature in the center of the pile should reach 130-150 degrees F. for an extended period. Three or four months after the initial loading, use a bucket loader to move the pile into the secondary bin. Add water if necessary. Check the temperature in the secondary bin to make sure it re-heats. Following the second heat cycle (another 2 to 4 months) the compost is ready to spread on a field. You may have some large bones remaining, but they can be put back into the primary bin for further breakdown. WHAT PROBLEMS CAN I ANTICIPATE WITH COMPOSTING? Odors: As long as you add sufficient carbon source to the pile and keep the carcass covered, odors should not be a problem. You may have odors emitted briefly when you turn the primary bin and move its contents to the secondary bin. Scavengers: You may have to fence the poster, but usually keeping the carcass well covered with carbon source is sufficient to keep odors down so that digging scavengers are not attracted. Leaching and runoff: Grade around the composter to keep clean storm water away from the bins. Don’t overwater the compost. Use proper type and sufficient amounts of carbon source materials. Insufficient composting rate or low temperatures: Adjust moisture as needed. In winter it is difficult to “jump-start” decomposition of a cold carcass. HOW DO I DISPOSE OF THE FINISHED COMPOST PRODUCT? Applying it to the field with a box type manure spreader is recommended because animal carcass compost is a very good source of fertilizer for the crops. It should not be given or sold as compost for off-farm use. The compost N, P, and K should be considered part of the nutrient management plan for the field. WHERE CAN I GET MORE INFORMATION ON COMPOSTING? NRCS Ag Waste Management Field Handbook (see http://www.wcc.nrcs.usda.gov/awm/awmfh.html). Illinois Department of Agriculture, Illinois Dead Animal Disposal Act and Code. (see http://www.legis.state.il.us/commission/jcar/admincode/008/008000900001100R.html). There are also several web sites at state land grant universities. WHERE CAN I BUY A COMPOST THERMOMETER? You can expect to spend about $90-100. Look for 36 inch long, 5/16 inch diameter stem. Two choices (about the same price) are listed: http://www.google.com/url?sa=t&ct=res&cd=3&url=http%3A//www.traill.uiuc.edu/dairynet/paperDisplay.cfm%3FContentID%3D7651&ei=HhwTQ6CAIMjy4QGo7-G8Cg Whole Animal Composting of Dairy Cattle Michael Looper, Ph.D., NMSU Extension Dairy Specialist Even the most well managed dairy operations experience animal loss due to weather, natural causes, and/or illness each year. Rendering services currently pick up most on-farm mortalities. However, with the concern of Bovine Spongiform Encephalopathy (BSE; commonly know as Mad Cow Disease), the feeding of animal-derived protein to cattle is prohibited. This has decreased the need for animal rendering and increased the cost of removing mortalities from the farm. The abundance of stockpiled manure and old feedstuffs on dairy operations make whole animal composting a feasible alternative to carcass disposal. Objectives of this publication are to outline factors that affect proper composting procedures and discuss how to compost cow mortalities on the farm. carbon and nitrogen ratios (C:N ratio) How To Compost Whole Cow Carcasses Bovine Composting Experiment in New Mexico Summary References: Field Guide to On-Farm Composting. 1999. NRAES-114. Ohio’s Livestock and Poultry Mortality Composting Manual. 1999. Ohio State University Extension Publication. On-Farm Composting Handbook. 1992. NRAES-54. Trinca, L. A., B. Miller, and F. R. Beard. 1999. Bovine Mortality Composting in Northern Utah. Presented at the ASAE/CSAE-SCGR Annual International Meeting, Toronto, Ontario. Department for Environment, Food and Rural Affairs Up to index 212/04 Livestock farmers are being urged to dispose of poultry litter and carcases properly following a marked increase in cases of suspected cattle botulism in England and Wales. From 1997 to 2002, the Veterinary Laboratories Agency investigated an average of four botulism incidents each year but 20 potential botulism outbreaks were investigated last year. The VLA said there was evidence that litter from deep-litter broiler houses was the cause of disease in many of the recent outbreaks. Investigations have revealed that affected cattle had direct or indirect contact with poultry litter when it was used as bedding for housed animals, as a fertiliser on grazing land and when it was stored in or adjacent to fields where cattle were grazing. Cases have also occurred when cattle were fed silage from fields fertilised with poultry litter. Losses have varied from a death of a single animal to the loss of up to 80 per cent of the herd. Botulism in cattle causes a progressive paralysis, beginning with stock becoming unsteady on their feet and ending several hours later in death. When botulism is suspected in food animals, the Food Standards Agency require that meat and milk are withheld from entering the food chain for two weeks after diagnosis of the last clinical case within the herd. Alick Simmons, head of Defra's veterinary epidemiology and zoonosis division, said that while there were benefits from recycling of poultry litter as fertiliser on farmland, farmers had to ensure that they were complying with the law. Spreading poultry litter on land which contained carcases or parts of carcases was illegal and put at risk the health of their cattle and possibly that of their neighbours, he added. Defra/VLA recommend that the following actions are taken to reduce the risk of disease and economic loss. Poultry carcases and carcase material must be collected and disposed of in accordance with the Animal By-Products Regulations 2003, ie by rendering or incineration. Notes for editors 1 Botulism is caused by either ingestion or preformed toxins produced by the bacterium "Clostridium botulinum" in decaying crops, vegetation or carcase material. Poultry litter may be a source of "Clostridium botulinum" organisms, spores or toxins. Botulism is not a notifiable disease. 2 The Animal By-Products Regulations 2003 (SI 1484) provides for the administration and enforcement of Regulation (EC) No 1774/2002 which prohibits the composting of poultry which die on farm and the application to land of manure or poultry litter containing carcase material. Local authorities are responsible for enforcement. 3 A letter from the VLA is today published in the Veterinary Record, providing advice to vets on the issue. END Public Enquiries: 08459 335577 http://www.defra.gov.uk/news/2004/040604a.htm Defra Helpline: 08459 33 5577 Helpline@defra.gsi.gov.uk Name Address Address Address Address To: All livestock farmers 17 April 2003 NEW RULES ON DISPOSAL OF FALLEN STOCK FROM 1 MAY 2003 I am writing to inform you about new EU legislation, the Animal By-products Regulation, which will ban the routine on-farm burial and burning of animal carcases when it applies in Member States from 1 May 2003. From that date the only legal methods of disposal will be rendering or incineration. The only exceptions from the ban in the UK are for remote areas of the Highlands and Islands of Scotland. On-farm incinerators will be allowed provided that they conform to certain standards and are approved. Guidance on incinerators is enclosed with this letter. Alternatively, you can, as now, contact your local knackerman and arrange for the carcase to be collected. If you do not know who provides this service in your area you can ring the help line on 0845 8507070 which will be in place by 1 May. The costs will depend on those prevailing in your area and must be agreed by you with your local collector. We are aware that the ban on burial will cause difficulties for some farmers who will be faced with increased costs of disposing of fallen stock. To help keep these costs down the Government is willing to assist with the setting up of a low cost voluntary scheme to which farmers can subscribe. Details of this scheme and how it would work are attached. You will see that compared to typical charges under existing collection arrangements there are substantial savings to be made. The Scheme can only be viable if sufficient people are willing to join and it is recognised that the full benefits of economies of scale can only be made when it is fully operational. The charges being proposed do not represent the full costs of the scheme. This is being heavily subsidised by government initially to enable it to become established although in the future the government would expect industry to take increasing responsibility for funding and operating the Scheme. In the event that take up is not adequate to make the scheme viable then farmers will need to make their own arrangements for collection and disposal of fallen stock and the government’s role will be limited to enforcement of the ban on on-farm burial and burning of carcases. If you are interested in joining such a scheme please register your interest by completing the attached tear off slip below by 6 May and returning it in the enclosed SAE. If interest is sufficient to warrant it we will contact you again with joining instructions. TSE Directorate Defra ------------------------------------------------------------------------------------------------------- Please tick boxes which apply below. I wish to register an interest in joining a scheme for the collection and disposal of fallen stock. Yes No If you do not wish to join such a scheme is this because: No longer have the cost have alternative arrangements any livestock please specify………………… Name BARCODE Address Address Signed ………………………………… Address FALLEN STOCK SUBSCRIPTION SCHEME How it will work The Scheme will be open to all agricultural holdings and all species of livestock on such holdings. Members will be given a membership number on payment of the subscription fee. It is proposed that there will be a central body set up jointly by Government and industry, but run by the industry, responsible for administering membership of the Scheme, collecting subscriptions and paying contractors. Members of the Scheme will then be entitled to have their fallen stock picked up free at the point of collection once their membership details have been verified. Collection will be undertaken by approved contractors who are able to meet the strict biosecurity standards required. In most cases this will be the local knackerman who is familiar with the farm. What it will cost The proposed fee is £100 per year for the average holding. There will be discounted rate of £50 for small holdings* and a higher rate of £200 for large holdings**. If there is a high uptake of the Scheme these rates should be sufficient to keep the Scheme self-financing with the aid of an initial government subsidy, but they will need to be kept under review in the light of experience and as government subsidy is reduced in the future. * Small holdings are defined as those with less than 20 cattle or 20 horses or 100 sheep or 100 goats or 100 deer or 100 pigs or 1000 poultry or for mixed holdings the equivalent of 20 cattle where 1 bovine = 1 horse = 5 sheep/goats/deer/ pigs or 50 poultry. ** Large holdings are defined as those with more than 200 cattle or 200 horses or 1000 sheep or 1000 goats or 1000 deer or 1000 pigs or 10,000 poultry or for mixed holdings the equivalent of 200 cattle where 1 bovine = 1 horse = 5 sheep goats/deer/ pigs or 50 poultry. NB All other livestock including exotic livestock will be considered = 1 bovine for this purpose How you can save money – some examples Medium holding with 50 cows, 50 -60 sheep and 60-70 pigs Based on estimates of mortality rates and typical costs for collection and disposal of fallen stock, a holding of this size could expect to have 2 cows (one of which is assumed to be under 24 months, and the other over 24 months which will be collected free as now under BSE testing arrangements), 3 sheep and 4 pigs requiring collection over a year. Typical costs of collection and disposal are: £90 per cow, £15 per sheep and £12.50 per pig. Total cost: £185 compared with subscription fee cost £100. Small holding with 40-50 pigs and 500 poultry Expected number of fallen stock are 3 pigs and 50 poultry. Costs are £12.50 per pig and £0.65 per bird. Total cost: £70 compared with subscription fee cost £50 Large holding with 100 cows, 600 sheep Expected number of fallen stock are 4 cows (assume one under 24 months as above), 30 sheep. Costs are : £90 per cow and £15 per sheep. Total cost: £540 compared to subscription fee cost £200. Q & A ON COLLECTION AND DISPOSAL OF FALLEN STOCK Q1 Why is ban on on-farm burial or burning to be introduced? Many farmers have buried stock on their farms for years and doubt whether there is any justification for this ban. The Commission’s view has been influenced by a number of scientific opinions which take into account factors such as the potential for polluting water courses and the lack of scientific information available on how persistent the prions that cause diseases such as BSE and scrapie are in soil. Q2 Why hasn’t government acted sooner? When will the Scheme start? The Government has been in discussion with the livestock and disposal industries since April 2002. A scheme was proposed as a means of encouraging compliance and reducing costs to individual farmers. However it is not needed as a means of establishing an infrastructure to dispose of fallen stock. DEFRA has received assurances from the knacker and rendering industries that this is already in place. The delay in progressing matters rapidly was because no agreement could be reached on how such a scheme would be funded. Q3 Will there be a transitional period to allow on- farm burial until a national scheme is in place? No. A national scheme is being proposed in order to reduce the cost of collecting and disposal of fallen stock and to encourage compliance. However, an infra-structure of knackers‘ yards and renderers throughout the country which farmers can use to comply with the new rules now. Q4 Who is responsible for the disposal of fallen stock? We take the view that all industries are responsible for disposing of their own waste and farming is no exception. If the industry signs up to this government subsidised voluntary scheme it will help maintain public confidence in its ability to dispose of its waste in a safe and sustainable manner. Q5 Is there sufficient capacity within the existing collection and disposal industry? The collection and disposal industries are confident that there is sufficient capacity within the existing infrastructure to deal with the estimated additional quantities of fallen stock. Q6 What will be the permitted routes for disposal of fallen stock? Are composting and bio-digestion permitted disposal routes? From 1 May under the new Animal By-products Regulation fallen stock must be disposed of to approved rendering or incineration facilities or hunt kennels (where they exist) (see below). The composting or bio-digestion of fallen stock is currently illegal. The new EU rules will not change this position, however if the EU Scientific Steering Committee are convinced by a report they have received from UK industry on biodigestion, this system of disposal may be permitted in the future. Q7 Will hunt kennels be permitted to collect fallen stock under the Animal By-Products Regulation? Yes. The Regulation will permit hunt kennels to continue collecting fallen stock. However, they will be required to upgrade to knackers' yard standards if they wish to do so for the purposes of feeding to hounds. DEFRA will issue hunt kennels with advice about how to go about this. Q8 Would State Aid Rules permit 100% Government funding of a National Fallen Stock Collection and Disposal Scheme? New Community guidelines for State aid allow Member States to fund aid 100% of collection and disposal costs only where the aid is fully recovered from the meat sector e.g. by a levy. Otherwise, Member States may grant State aid of up to 100% of costs of collection, and 75 % of the costs of destruction of fallen stock. Q9 Do other Member States fund National Fallen Stock Collection and Disposal Schemes? The situation regarding Government funding in other Member States is complicated. Based on data provided by each Member State, the European Commission issued a paper on 20 November 2001. It showed that the level of Government support varies across the Community, with farmers in some countries paying the full cost of disposal while in others the Government or local authority provides varying levels of support. Furthermore, in some cases Government recoups the costs, for example, in France this is done through a tax levied on the retail sales of meat. Q10 Does the Government have a statutory obligation to pay for the collection and disposal of fallen stock for the purpose of TSE Testing? No. Although the testing of all fallen cattle aged over 24 months for BSE is required by the EU TSE Regulation, the Regulation does not require Member States to pay for the collection or disposal of these carcases. The decision was taken by Defra to provide Exchequer funding to ensure that all required carcases would be tested to assist DEFRA in meeting their EU obligations. This would continue to be the case if a subscription scheme were to be set up although this position may change if the requirements for testing change. Cattle farmers may still wish to join the subscription scheme in order to benefit from having cattle under 24 months and calves picked up free at the point of collection. Q11 Who will enforce the new legislation on the disposal of animal by- products, including fallen stock? Local authorities, usually Trading Standards, who currently enforce the Animal By-Products Order 1999, will be the enforcement authority for the EU Animal By-Products Regulation. Q12 How can the new EU rules be enforced? It is important that carcase movements are fully traceable. Both the Animal By-Products Order 1999 and the EU Animal By-Products Regulation require the keeping of records of any carcases that are sent off-farm for disposal elsewhere. Enforcement authorities will check that such records exist and the number of carcases disposed of. Inspections will also be made of on farm incinerators to check that they comply with the standards required in the Regulation. Q13 What about Fly-tipping? Wherever possible, where a carcase is dumped on private land, the owner of the animal will be identified and held responsible. However, if ownership cannot be proven, responsibility for disposal rests with the landowner. The local authority, usually Trading Standards, has powers under the statutory nuisance provisions of the Environmental Protection Act 1990 to deal with "accumulations or deposits which are prejudicial to health or a nuisance". Appropriate action can subsequently be taken against the owner of the carcase. GUIDANCE ON ON- FARM INCINERATORS As an alternative to joining the National Fallen Stock Collection Scheme you may wish to consider incinerating carcases on your farm. This is allowed, but you will need to comply with the legislative controls that apply to on-farm incinerators. WHAT ARE THE CONTROLS ? Approval Your incinerator will need to be approved. If you only use your incinerator for animal carcases it needs to be approved by the State Veterinary Service. If you burn other materials as well it will need to be approved by either the Local Authority or the Environment Agency, depending on its size. Incinerators which operate at more than 1 tonne/hour are authorised by the Environment Agency (or SEPA in Scotland). Incinerators which operate at between 50kg/hour and 1 tonne/hour are authorised by the Local Authority in England and Wales, but by SEPA in Scotland. Planning permission may be required, particularly for incinerators which operate at more than 50kg/hour. Standards for incinerators Low capacity incinerators (less than 50kg/hour) • Must be designed, equipped and built so that the gas in the secondary chamber achieves 850ºC for 2 seconds. The temperature will need to be monitored by a temperature sensor that measures the temperature of the gas leaving the chamber. High capacity incinerators (over 50 kg/hour) • Must also be designed so that the gas in the secondary chamber reaches 850ºC for 2 seconds, but in addition- • Each line must be equipped with at least one auxiliary (ancillary) burner. This must come on automatically at start up until the temperature is reached and at any point during combustion if the temperature falls below 850ºC. Requirements for approval In addition to meeting the equipment standards outlined above, you will need to meet some additional requirements to obtain approval. • There must be total physical separation between the incinerator and the livestock and their feed and bedding with fencing where necessary. • Farmers must incinerate only their own fallen stock unless the incinerator is approved as a shared incinerator (see below for further information). • Ruminant carcases must be incinerated whole. Large ruminant carcases (e.g. large bovines) must be sent off site for disposal if they are too big to fit the incinerator without cutting up. • Pigs and poultry can be cut up e.g for post- mortem. But they must be cut up in a suitable area, the fluid must be collected and incinerated and the by-products incinerated immediately. • Any equipment (e.g. the shovel) must be dedicated to the operation of the incinerator and not used elsewhere on the farm. Remember also that no incinerator can operate effectively if it is overloaded. Mobile incinerators Mobile incinerators can be valuable for disposing of material that it is preferable not to have to move off site e.g anthrax cases. However they also have the potential to spread disease from farm to farm. If they are to be used they will need to comply with strict biosecurity measures and be operated by a dedicated operator. They must also be designed and managed in such a way as to prevent unauthorised or accidental release of any polluting substances into soil, surface water and ground water. Shared incinerators If farmers want to share a stationary incinerator it will need to be sited on premises on which no livestock are kept. If the premises was originally part of a livestock holding it must be completely separated with a dedicated entrance and equipment. You should also be aware that although a Waste Management Licence is not needed at present the requirements are expected to change in 2004. At that time shared incinerators which operate at below 50kg/hour will additionally require a Waste Management Licence issued by the Environment Agency or SEPA. This does not apply to low capacity incinerators that are used only to dispose of stock that die on the farm on which the incinerator is located. TIMING Low capacity incinerators • New incinerators will need to comply with all the requirements from 1 May 2003. • For incinerators that were in place on 1 November 2002 there is a transition period to allow inspection of the premises to take place and operators to modify or replace their incinerators as necessary. This ends on 30 December 2004. • If a low capacity incinerator, (<50kg/hour), is to be used to incinerate SRM or ruminant carcases from which the SRM has not been removed, all of the provisions of the new Regulation must be complied with from 1 May 2003. Farmers are advised to contact their local Defra Animal Health Office for advice. High capacity incinerators • New incinerators must comply now. The relevant legislation took effect on 28 December 2002. • Incinerators installed before 28 December need to meet the full requirements by 28 December 2005. http://www.defra.gov.uk/animalh/by-prods/fallen/NewRules.pdf Minutes of the open session of the 87th meeting held on 21st April 2005 At The Conference Centre Holiday Inn Bloomsbury Coram Street London WC1N 1HT snip... 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 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. snip... http://www.seac.gov.uk/minutes/final87.pdf TSS
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