Health Scientific Committees Scientific Steering Committee (former MDSC) Outcome of discussions

Scientific Opinion - The safety of meat and bone meal from mammalian animals, naturally or experimentally susceptible to Transmissible Spongiform Encephalopathies. Adopted by the Scientific Steering Committee at its meeting of 26-27 March 1998 following a public consultation on the preliminary opinion adopted on 19-20 February 1998 ( Version updated on 3.04.98 ) - Background

I. Report of the Working Group

1. Definition of meat and bone meal derived from mammalian animals.

- The definition and report hereafter do not refer to blood meal.

- For the purpose of the present report, meat and bone meal, derived from mammalian animals, is defined as processed animal protein intended for animal consumption, treated so as to render it suitable for direct use as a feeding stuff or as an ingredient in a feeding stuff for animals.

- In the frame of the present report, rendering means any processing of slaughter by-products (excluding pure blood), animals unfit for human consumption or of meat scraps for the production of meat and bone meal. The term "rendering" includes the collection of such materials and subjecting them to minimal processing, or distribute them to firms other than renderers whose intended use for the products may include animal feed. The term includes also blending animal protein products.

2. Background

a) On the basis of a large experiment carried out between 1991 and 1997 (often referred to as "the rendering study", see Taylor et al., 1995; MAFF et al., 1997), the process conditions of 133°C during 20 minutes at 3 bar are confirmed to result in a safe product. This is acknowledged in various opinions of the Scientific Veterinary Committee (ScVC, E.C., 1996), for example:

- on 18.04.96: : "(...) The only method known to be effective at present is heat treatment at 133°C at 3 bar for 20 minutes. It was noted that it may be possible to achieve the same parameters in a continuous system, although data was not provided. The Committee considers that any system which is proven to be operating to the stated parameters will give a product of equivalent safety, irrespective of whether it operates as a batch or continuous system."

- on 21.10.1996: "The ScVC recommends that minimum standards for processing waste of mammalian origin to produce meat-and-bone meal (equal or greater than processing at 133°C, 3 bar for 20 min) should be immediately put in place. (...) Various options were considered which could reduce any risks for animal health (and public health in the long term) in the interim period before the new standards are fully implemented. These include:

a) (...), b) (...), c) the exclusion of the highest risk ruminant tissues from rendering systems, i.e. a minimum exclusion of specified risk materials; d) (....)"

b) On 18 July 1996, the European Commission adopted Decision N° 96/449/EC on the approval of alternative waste treatment systems for processing animal waste with a view to the inactivation of spongiform encephalopathy agents. This Decision defines the minimum parameters for the processing of animal waste excluding fats as: a maximum particle size of 50mm, a temperature higher than 133°C, a duration of 20 minutes and a pressure (absolute) of 3 bar. Processing may be carried out in batch or continuous system.

c) The so named "Report of the Committee Dormont" of July 1996 states (République Française, 1996):

"(...) The treatment consisting of a discontinuous process of 133°C / 3 Bars / 20 minutes of particles of 50 mm obtained from condemned carcasses (in French: "cadavres de saisies d'abattoir") and from the central nervous system, should not be considered as capable of inactivating totally the agent of sub-acute transmissible spongiform encephalopathies. Indeed:

- the laboratory experiments have shown that the thermal treatment at 133°C during 20 minutes on its own cannot guarantee the sterility of the product regarding non conventional transmissible agents (in French: Agents transmissibles non conventionnels, ATNC) and that its efficacy could vary significantly according to the state of desiccation of the product and its content with lipids (Brown et al., J.Inf.Dis., 1990; Wright and Taylor, The Lancet, June 1993; Taylor et al., Veterinary Record, December 1995);

- the published works relate to experiments using limited volumes of material; hence the results cannot be extrapolated with certainty to industrial volumes.

(...) the [Dormont] Committee recommends the evaluation of procedures susceptible of reinforcing the efficacy of the thermal treatment. (...) On the other hand, the efficacy of a delipidation with solvents followed by a thermal treatment, seems important to be evaluated in comparison with the sole thermal treatment. (...) In a more general way, and taking into account the multitude and complexity of the [existing] processes, the [Dormont] Committee recommends an homologation [of production processes] on a case by case basis. The Committee also recommends an homologation of the machinery used in the inactivation processes. (...)

d) When it adopted its opinion on Tallow on 8.09.97, the MDSC/SSC referred to the International Scientific Conference on Meat and Bone Meal (Brussels 1&2 July 1997, E.C., 1997) where the issues related to the inactivation / elimination of the BSE infective agent where addressed:

"(...) A third safeguard is a transformation process. So far it was accepted that no infectivity could be found after exposing even infected material over 20 minutes to a temperature of 133°C at 3 bar or an equivalent method with demonstrated efficacy. However, during the International Meat and Bone Meal Conference held in Brussels on 1 and 2 July 1997, it was not excluded that under worst case conditions, traces of infectivity could remain. This implies that the only safeguard at present is the certified origin of the material from which the product is derived AND an appropriate production process following acknowledged production rules."

e) It can thus be concluded that a production process which respects the conditions of "a maximum particle size 50 mm, a process of 133°C at 3 bars during 20 minutes" is presently the most appropriate one for inactivating / eliminating the BSE infective agent when producing animal derived products such as MBM, but these conditions as such do not fully guarantee a totally safe product if the raw material was highly contaminated.

On the basis of what precedes, the MDSC/SSC decided during its meeting of 16 October 1997, to create a working group on the safety of Meat and Bone Meal. This report was prepared by that working group.

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