EU Animal By-Products (ABP) legislation permits fertilisers containing mammalian meat and bone meal (mMBM) derived from Category 2 and Category 3 ABPs* to be spread upon non-pasture land. In March 2006, the United Kingdom TSE legislation was amended to lift the ban on the application of Category 3 derived organic fertiliser and soil improvers (OFSI) on agricultural land. However, the TSE Regulations prohibit mMBM being brought on to premises on which farmed animals are kept, unless it is “incorporated” into OFSI produced and used in accordance with the EU ABP Regulation.
An original quantitative release assessment was commissioned by Defra and completed in December 2005 (Cummins and Adkin, 2007), which evaluated the amount of potential BSE and scrapie infectivity available in the soil of non-pasture land post application of Category 3 ABP derived fertiliser processed using Method 1** rendering. This work was presented to SEAC Meeting 87 (21 April 2005) and reviewed internally by members of that Committee. In 2008 this work was extended to a full quantitative risk assessment (QRA) evaluating the risk to cattle and sheep of becoming infected with BSE and/or scrapie as a result of use of rendered Category 3 ABP derived fertiliser. The QRA assumed that the mMBM was manufactured by rendering to Method 1 or one of the less stringent methods available (2 to 7). This QRA was presented to SEAC Meeting 103 (24 November 2009) and reviewed internally by members of that committee giving rise to a number of recommendations.
The purpose of this proposal is to extend and update the 2008 QRA, in particular:
1. Update the parameters in the original QRA for the rendering of ruminant derived Category 3 ABPs into OFSI by either Method 1 or Method 7
2. Complete a QRA for the rendering of ruminant derived Category 2 ABPs into OFSI by Method 1
3. Amend the consequence assessment to include the susceptible population of sheep for exposure to cattle BSE, and include the risks associated with atypical scrapie.
4. Whereas the main QRA estimates the National risk from the application of such OFSI, a case study estimating the individual risk will be developed investigating the issue of heterogeneity of distribution of infectiousness.
5. Case study investigating the risk associated with sequential application of such OFSI in locations over time and any subsequent decay that may occur.
The OIE framework for risk assessment of release, exposure and consequence assessment, will be used as with the original QRA. The end result of the risk assessments, therefore, will be a quantitative estimate of risk (the number of new TSE infections). A sensitivity analysis will also be undertaken to ascertain the impact that any uncertain parameters have on the final output of risk. In doing so, those parameters which have a large impact on the results can be identified and further research undertaken to assist in reducing the uncertainty in the model inputs. In summary, the risk assessment models proposed will follow a similar approach to that produced by Cummins & Adkin (2007).
The risk assessment models will be parameterised with the most recently available data from the scientific literature, VLA studies, and in collaboration with expertise from the Meat and Hygiene Service (MHS) and Animal Health (AH). It is likely that there may be gaps in knowledge for some model parameters in which case expert opinion will be sought. The resulting model framework, data, model assumptions, results and sensitivity analysis will be provided within a technical report and subject to review by Defra and other scientific bodies if required.