Volume 11: Scientists after Southwood
4. The Spongiform Encephalopathy Advisory Committee (SEAC)
Deliberations and advice
3. Advice on slaughterhouse practices and MRM

3. Advice on slaughterhouse practices and MRM

4.244 The introduction of the human Specified Bovine Offal (SBO) ban in November 1989 led to concerns being raised regarding the potential for meat intended for human consumption to be contaminated by the designated offal during the process of its removal in the slaughterhouse. The principal areas of concern which were ultimately referred to SEAC were:

1. Head-splitting: The splitting of the skull in order to remove the brain caused concern because of the potential for brain material to contaminate head meat, which was often removed thereafter and used for human consumption.
2. Carcass-splitting: It is a requirement of European meat hygiene legislation that bovine carcasses are split following slaughter. This was achieved by the use of a circular saw which was passed down the back of the carcass splitting the spinal column. Concerns over this practice were twofold. First, there was potential for the spinal cord to be 'shredded' during splitting so that small fragments could become lodged in the spinal column. Second, the saws might throw up spinal cord material onto the surrounding carcass including meat for human consumption.
3. Pithing: After the animal has been stunned the pithing rod is inserted into the skull and pushed down the spinal canal for a length of about one metre and then withdrawn. It is designed to destroy spinal nerve roots so as to prevent the reflex, convulsive kicking that is sometimes seen in stunned cattle. Concern was expressed that meat for human consumption might become contaminated with brain or spinal cord material as a result of contact with the pithing rod or material discharged during the pithing process.
4. Mechanically Recovered Meat (MRM): A number of mechanical methods were used to remove residual meat from the bones of the carcass after manual deboning had taken place. Concern was expressed that MRM could be contaminated with spinal cord fragments which remained in the spinal column after carcass-splitting.

4.245 Each of the above processes is described in detail in vol. 13: Industry Processes and Controls. In addition, the consideration given to these processes by MAFF and DH, which led to these matters being put to SEAC, is described in full in vol. 6: Human Health 1989-1996. What follows here is a brief summary of the evidence put to SEAC, their deliberations and conclusions.

Head-splitting

4.246 The potential problems associated with the practice of head-splitting were drawn to the attention of MAFF almost immediately after introduction of the SBO ban. Concerns were raised by a number of Environmental Health Departments of local authorities responsible for enforcement of the SBO regulations. ¹ These concerns were then taken up by the Institute of Environmental Health Officers (IEHO) which canvassed its members regarding the effectiveness of the regulations and communicated their responses to MAFF. Among the matters addressed by the IEHO was the fear that the practice of head-splitting, prior to removal of head meat, might lead to head meat used for human consumption becoming contaminated with brain material. ²

4.247 To help assess the validity of the complaints being received, in early February Mr Stephen Hutchins, SVO, Red Meat Hygiene Division, MAFF, ³ visited selected abattoirs to review brain removal methods. His report to Mr Keith Baker, Assistant Chief Veterinary Officer (Meat Hygiene), concluded that the 'very small amounts of a bone paste that would have included traces of brain tissue', produced by three different methods of sawing through the head and brain, might be transferred to cheek meat, 'but only in tiny quantities'. An alternative method involving the use of water and air jets posed 'some risk' of contamination and 'represented the least hygienic method witnessed'. However, he saw no reason for prohibiting the 'open-skull' methods, provided saws and work surfaces were adequately cleaned down between heads. ⁴

4.248 In the face of continuing concern, Mr Gummer 'undertook to organise a review of the contrasting arguments put forward by the EHOs and the SVS'. He would 'invite a suitable outside expert to advise him'. ⁵ Mr Andrews suggested that Dr Tyrrell, Chairman of SEAC, was not 'necessarily an appropriate person to make judgements about butchery practices', and recommended Mr A M Johnston, senior lecturer at the Royal College of Veterinary Surgeons. ⁶

4.249 Mr Gummer agreed to this, ⁷ and Mr Meldrum wrote to Mr Johnston on 1 March 1990 enclosing Mr Hutchins's report. He asked whether Mr Johnston 'could let us, as an independent expert, have your assessment of this report'. ⁸

4.250 Mr Johnston sent his report to Mr Meldrum on 7 March 1990. This expressed reservations about all the methods identified in Mr Hutchins's report, especially the high-pressure water/air method - 'I am convinced that this method is not acceptable if contamination of the meat on heads is to be avoided'. He concluded that 'whenever possible, meat intended for human consumption should be removed before any saw cut which enters the cranium is made'. ⁹

4.251 On 29 March 1990, Ms Bronwen Jones, Meat Hygiene Division, distributed a first draft of a guidance note to local authorities on head-splitting, which was intended to take into account Mr Hutchins's and Mr Johnston's reports. The note explained that:

Brains may be removed at the slaughterhouse, in which case there are no further requirements in the Regulations governing the removal of head meat. Concern has been expressed that the practice of removing brains before the head meat is removed gives rise to the risk of cross-contamination of that meat with brain tissue. Since the brain tissue in question is from healthy animals, it follows that the risk is in any case negligible. ¹⁰

4.252 The guidance included the following principles which, if followed, 'will ensure that any transfer of brain tissue to meat is kept to an absolute minimum':

1.Where possible head meat intended for human consumption should be cut from the skull before any cut is made into the skull to remove the brain.

2. Where this is not possible, heads should be opened in such a manner that the possibility of brain tissue being spread to meat is kept to an absolute minimum.

3. It is recommended that the removal of the brain should take place within 24 hours of slaughter. Where this is not possible skulls should be stored prior to opening under chilled conditions. ¹¹

4.253 The guidance also included 'recommended techniques':

The preferred technique for opening the skull prior to brain removal is an oblique cut through the skull with a reciprocating saw, from a line immediately anterior to the normal site of the captive bolt hole (but avoiding the hole itself) to a line immediately above the foramen magnum. This will allow the easy removal of the brain without exposing meat to the possibility of contact with the minimum amounts of brain tissue that might escape from the skull during the sawing operations.

If this method of removal is unavailable the skull may be split along the middle of the head in the median plane with a band saw. Before this technique is employed, all the meat from around the area of the hyoid bones and the base of the skull should be removed.

Methods involving the use of high pressure water jets to remove brain tissue from otherwise intact skulls are not recommended in view of the amount of splashing of brain tissue and water that occurs. ¹²

4.254 However, concerns continued to be reported to the Government about the removal of brain before head meat. The IEHO reiterated its view that the practice should be expressly prohibited. ¹³ In addition, representatives of consumer groups met with Ministers and officials in May and voiced their own concerns about the practice. ¹⁴

4.255 On the night of 21 May 1990, there was a debate in the House of Commons on the Government's handling of the BSE outbreak. During the debate further concerns were expressed by Mr Matthew Taylor MP about the practice of head splitting. Mr Gummer responded:

I thank the hon. Gentleman for his comments about what I have done. I hope that he recognises that the matter has gone to the Tyrrell Committee because our expert advice is that what we are doing is in general perfectly acceptable. However, I do not want there to be a scintilla of doubt. ¹⁵

SEAC considers 'head-splitting'

4.256 SEAC considered head-splitting guidelines during its 13 June 1990 meeting. The guidelines were essentially the same as those produced by Ms Jones earlier (see paragraphs 4.251-4.253 above). However, there were some drafting amendments, which had been effected under Mr Andrews's 'chairmanship' on 23 May 1990, ¹⁶ to emphasise that head meat intended for human consumption should be removed prior to the brain being removed, and high pressure water hoses should not be used to remove brain tissue. SEAC concluded that:

[P]recautions about the removal of the brain from bovine skulls were a common sense measure. It was not consistent with this policy to permit the removal of the brain before head meat was harvested. ¹⁷

4.257 Ministers agreed that guidelines should be issued reflecting SEAC's advice. ¹⁸ On 14 June 1990 Mr Meldrum sent a telex to all Divisional Veterinary Officers (DVOs) and Regional Veterinary Officers (RVOs) in England, Scotland and Wales, all Regional Meat Hygiene Advisers (RMHAs), and a number of industry, retail and professional bodies. This included the following guidelines:

As a result of a detailed evaluation of practices currently in use in slaughterhouses and boning plants the Ministry of Agriculture, Fisheries and Food has concluded that bovine head meat must be recovered from the intact skull before the brain is removed. ¹⁹

Evidence to the Agriculture Select Committee

4.258 As described earlier, Dr Tyrrell gave evidence to the Agriculture Select Committee in June 1990. During evidence to the Committee, Dr Tyrrell discussed SEAC's consideration of head-splitting practices. He noted that head-splitting practices could lead to contamination of meat for human consumption, and continued:

It is, therefore, inconsistent to say, 'We want to prepare the meat so that it can be safely eaten even if the animal is infected' and then contaminate it again in the process of preparing it . . . Our conclusion was that it should not be allowed. ²⁰

4.259 In its report, which was published on 10 July 1990, the Committee said that an area of particular concern was that action should be taken to make the ban on specified offal as watertight as possible. In particular:

We do, however, feel in a position to recommend that the practice of splitting the heads of cattle in abattoirs be outlawed. It brings no significant benefits to anybody and is practically guaranteed to spread public alarm.

We were pleased to note that Dr Tyrrell voiced similar reservations about the latter practice. Recent MAFF guidelines also stipulate that 'bovine head meat must be recovered from the intact skull before the brain is removed'. This is a substantial step in the right direction, although we would like to see appropriate safeguards enshrined in legislation at an early opportunity. ²¹

4.260 Dr Tyrrell wrote to Mr Gummer on 23 July communicating SEAC's advice in relation to brain removal from bovine skulls. He stated:

[T]he specified offal ban . . . is designed to remove certain nervous and lymphatic tissue, including brain, from the human food chain. To be consistent, slaughtering practice should therefore also ensure that possibly infected brain and spinal cord material does not contaminate muscle tissue destined for human consumption. Various procedures such as sawing the skull open or driving the brain out by water pressure would disperse brain tissue which could contaminate meat and would not be satisfactorily removed by washing. Such procedures should therefore be carried out in such ways and places that contamination of meat does not occur. We therefore recommend, as far as bovine heads are concerned that head meat should be removed from the skull before the brain is removed. ²²

4.261 On 21 November 1990, the Government published its response to the Agricultural Select Committee's report and recommendations. The response noted the Select Committee's recommendation that head meat should be removed from the intact skull before the brain is removed and stated:

The Government accepts the principle of these recommendations. An amendment will shortly be made to the Bovine Offal (Prohibition) Regulations 1989. It will lay down that head meat must be recovered from the intact skull before the brain is removed, thereby avoiding any possibility of contamination through brain tissue. ²³

Bovine Offal (Prohibition) (Amendment) Regulations 1992

4.262 The Bovine Offal (Prohibition) (Amendment) Regulations 1992 came into force on 12 March 1992. These Regulations:

1. prohibited the removal of any meat for human consumption from the head of a bovine animal after the skull had been opened or the brain had been removed; ²⁴
2. prohibited the removal of the brain from the head of a bovine animal in a slaughterhouse or boning plant except in a specific area which at no time was used for food for human consumption; ²⁵ and
3. permitted those bovine heads from which the brain had not been removed to be moved under a movement permit to premises of a processor or a place of storage before transfer to a processor. ²⁶

Slaughterhouse practices and MRM

4.263 Following their discussion of head-splitting practices on 13 June 1990, SEAC considered the potential for contamination of meat with spinal cord and asked for further advice. The minutes of the meeting record the following observation:

Similar issues arose with spinal cord; if it made sense to avoid contamination by brain tissue of meat for human consumption it appeared on the face of it to make equal sense to avoid the contamination of such meat with spinal cord, which was just as likely to carry infection. Further information was needed on this. ²⁷

4.264 This concern had particular relevance to the safety of Mechanically Recovered Meat (MRM).

4.265 At the meeting which took place on the same day between Ministers and senior MAFF officials, it was recognised that SEAC would not be expert in the procedures involved in the MRM process, so it would be necessary for MAFF to prepare a paper on the technical issues involved. ²⁸ Mr Meldrum and Mrs Attridge were asked urgently to take forward the preparation of a detailed assessment of the possible hazards of MRM. ²⁹

4.266 It was not until October 1990 that Mr Lowson produced the final draft of the paper for SEAC. A detailed account of the drafting of the paper is to be found in vol. 6: Human Health, 1989-1996, ch. 4. The final draft added to the consideration of MRM a section provided by Mr F Taylor, Meat Hygiene Division, on 'Carcass-splitting', and a further section on 'Pithing rods'. At the suggestion of Mr Bradley, the section on carcass-splitting included the following information:

The splitting of the bovine carcass the last major dressing operation prior to carcass inspection. The carcass is spread so that the hind legs are anchored as far apart as is practicable. The back saw cuts down from the sacro-coccygeal area through the mid-line of the spinal column until the two halves are separated. In most cases a reciprocating saw is used. This has relatively slow action and produces visible amounts of bone waste . . . The spinal cord will inevitably receive some damage during this operation, although it is often surprisingly intact. It will generally be removed by use of a blunt hook, or similar implement, drawn down the length of the spinal canal.

The concern that has been expressed regarding carcass-splitting relates to the possible transfer of material from the damaged spinal cord onto the carcasses. The volume of material is likely to be small, in most cases no more than a few grams. It will be concentrated around the cut surface of the spinal column, perhaps with some slight spill over onto exposed meat surfaces. The routine washing of the carcasses will, if done sufficiently promptly (as would be normal practice), remove the greater part of any gross particular matter. However no data are available about the quantity of spinal cord tissue likely to come into contact or remain with material used for human consumption. Such data could be obtained by comparing the mean weight of spinal cord collected after splitting with that obtained after necropsy using a standard procedure to account for the length of spinal nerves, etc. ³⁰

4.267 In relation to MRM, the paper stated:

Inevitably when bovine carcasses are split through the centre of the vertebral column in the slaughterhouse some nervous tissue can remain and some contamination of the vertebrae with central nervous system (CNS) tissue can occur. This will be as a result of:

(a) small pieces of spinal cord inadvertently remaining in the vertebral column;

(b) contamination from carcass-splitting; or

(c) the failure to remove nerves from between the vertebrae.

It is unlikely that lymph nodes and other nervous tissue associated with the muscle are left adhering to the bones, since only residual meat remains after the deboning stage. However, there will probably be some peripheral nervous tissue still present within the vertebral column. Therefore, any risk passed by MRM would seem to be by the transference of the BSE agent from nervous tissue to the MRM. It is still not known however, if even where the spinal cord is removed cleanly, any risk exists from the remaining nervous tissue in the vertebral column. ³¹

4.268 The paper listed areas in which research could be useful; including

the quantification of the extent of any residue of CNS tissue left with the carcass when the cutting process is complete;

assessment of possible alternative methods of removing the spinal cord or cutting the carcass;

methods of detection of CNS tissue in MRM, and then determination of the presence of CNS tissue in MRM. ³²

4.269 In respect of pithing, the paper stated:

Since the rod is introduced into the skull at the start of the dressing line, before the hide has been removed, there should be no transfer of neural tissue onto exposed meat. That part of the skull around the captive bolt hole is not in any case used in foods intended for human consumption. The rod itself will have traces of the spinal cord on its surface, but these should be removed during the washing and sterilisation that occurs between each carcass. ³³

4.270 The paper closed with a one-paragraph conclusion inviting the Committee to:

Consider on the basis of the available evidence whether any action or guidance is required in relation to slaughterhouse practices, and whether any new R&D is needed. ³⁴

4.271 Before their sixth meeting, at which they discussed the paper on slaughterhouse practices, most of the members of SEAC between them visited two slaughterhouses. Dr Kimberlin later gave this description of the visits to the Lamming Committee:

Committee members had visited commercial abattoirs to witness the removal of the spinal cord from carcasses, and had been very impressed by the way it had been performed. The spinal cord had been surprisingly tough and easy to remove . . . the demonstration had probably taken place in the better slaughterhouses, and that the purpose of the visits was to assess the feasibility of spinal cord removal, not how well it was done in all slaughterhouses. ³⁵

SEAC's conclusions

4.272 SEAC considered the paper at its sixth meeting on 1 November 1990. The minutes do not record any specific discussion of MRM. In relation to slaughterhouse practices, they record:

Those members who had been involved in the slaughterhouse visit had noted that, if proper procedures were followed, specified offals could be satisfactorily removed at the slaughterhouse, and in particular that the spinal cord could be extracted from the carcass without difficulty. The Committee therefore concluded that, provided all the rules were properly followed and supervised, there was no need to recommend further measures on the grounds of consumer protection (operator safety was a matter for HSE). ³⁶

4.273 In a statement to the Inquiry, Dr Tyrrell stated on behalf of SEAC that:

The advice given by SEAC was expressed to be subject to a proviso or condition. That condition or proviso is set out above and is in the use of the words 'if' and 'provided'. It is necessary to read the conclusion in full to understand it. It was for Ministers and their officials to consider SEAC's advice and decide if the provisos or conditions explicitly mentioned could be met . . .

SEAC members regarded giving advice, in the qualified terms in which it was expressed, to be within their role and expertise. The conclusion was, essentially, negative. ³⁷

4.274 Mr Lowson summarised the Committee's position in a minute to Mr Maclean, which was copied to, among others, Mr Gummer, Mr Andrews, Mr Capstick, ³⁸ Mr Meldrum, Mrs Attridge and Mrs Brown. This stated that SEAC had specifically considered

. . . the issues raised by carcase splitting, mechanically recovered meat and pithing rods. This included visiting two slaughterhouses and seeing the slaughtering process at first hand. In the light of these visits and of papers prepared in Tolworth [MAFF HQ] the Committee concluded that so long as the rules were properly observed and proper supervision was maintained, there was no need to recommend further control measures on grounds of food safety.

The Committee does not intend to produce a formal document setting out this advice, but are aware that Ministers may choose to make some kind of public announcement. ³⁹

4.275 Mr Lowson suggested that the advice be announced by an appropriate insertion in the Government Response to the Report of the Agriculture Select Committee. A handwritten note at the foot of the minute records that Mr Maclean was content with this approach. ⁴⁰

Discussion

4.276 SEAC's 'advices' on slaughterhouse practices are discussed at length in vol. 6: Human Health, 1989-1996, ch. 4. So far as brain removal was concerned, the critical question was whether contamination of head meat was possible from the splitting of the skull and the removal of brain was cause for concern. MAFF officials expressed the view that it was not, because it would come from healthy animals and because the amount of contamination would be very small (see paragraphs 4.247 and 4.251 above). This was, however, a matter on which SEAC were better placed to form an opinion. Their opinion was that the potential contamination should be avoided by requiring head meat to be removed while the brain was intact. This was robust advice given 'as a matter of common sense' without any sophisticated analysis of the amount of contamination involved or weighing of the financial consequences of this advice.

4.277 The outcome of SEAC's consideration of other slaughterhouse practices was less satisfactory. We refer to our detailed discussion of what went wrong in vol. 6: Human Health, 1989-1996, ch.4. Here we have merely set out our resume at the end of that discussion.

4.278 Mr Gummer had been reassured by his officials that there was no cause for concern about MRM. There was, however, public concern about slaughterhouse practices in general and MRM in particular, which was reflected in Parliamentary attacks on the Government's handling of BSE.

4.279 In these circumstances Mr Gummer decided to refer slaughterhouse practices to SEAC. SEAC did not have expertise in the technical aspects of slaughterhouse practices, but was well qualified to express a view on the significance of any contamination that resulted from them.

4.280 The reference of slaughterhouse practices to SEAC stimulated MAFF to carry out a detailed assessment of the contamination consequent upon carcass-splitting for incorporation in a comprehensive paper on slaughterhouse practices for SEAC. Contributions were made from various divisions including the State Veterinary Service, Meat Hygiene Division, Food Standards Division and Food Sciences Division.

4.281 This assessment noted that inevitable contamination would result from small pieces of spinal cord inadvertently remaining in the vertebral column. It also explained that carcass-splitting would inevitably, on occasion, transfer tissue from the spinal cord onto the carcass, where it would be concentrated around the cut surface of the spinal column. How much of this would remain after routine washing and be transferred into MRM recovered from the spinal column was unknown.

4.282 Those who carried out this assessment identified a number of options to address this contamination problem. The least was the giving of advice on carcass-splitting to the slaughterhouse operators and on inspection to local authorities. The preferred option, if the amount of contamination entering MRM was unacceptable, was to ban recovery of MRM from bovine vertebrae. Further research was desirable to quantify the contamination.

4.283 At this point most of the task necessary for assessment of the risk had been done. Input from SEAC was needed by way of confirmation that officials' proposed action was appropriate having regard to the contamination that MAFF officials had diagnosed as inevitable.

4.284 Had this question been put to SEAC we have little doubt that it would have endorsed the proposal for research to quantify the amount of spinal cord getting into MRM. In the event, having been asked to advise generally, SEAC advised on the basis of its own assessment that if slaughterhouse procedures were properly carried out there would not be a problem. This assessment was at odds with that of the authors of the paper, who were better qualified to make it.

4.285 SEAC's advice was treated as establishing definitively that the contamination described in the SEAC paper was not cause for concern. The effect of SEAC's advice was that no action of any kind was considered necessary or taken to address the potential risk posed by MRM until 1995. This demonstrates a serious breakdown in communications. SEAC's intervention had hindered rather than helped the process of risk evaluation and management.

4.286 This unhappy chapter in the BSE story demonstrates the importance of targeting advice sought from expert committees so as to ensure that they provide input based on their expertise. It also demonstrates the dangers of overloading a part-time committee of busy people.