ACMSF 48th minutes 26 June 2003

Final minutes of the 48th meeting of the Advisory Committee on the Microbiological Safety of Food held on 26 June 2003 at Aviation House, 125 Kingsway, London, WC2B 6NH at 10.30 am.

Professor D L Georgala

Dr G R Andrews
Dr D W G Brown
Dr K M Hadley
Mr A Kyriakides
Mr P Mepham
Dr S J O'Brien
Mr B J Peirce
Dr Q D Sandifer

Mr P J R Gayford (DEFRA)
Dr J Hilton (FSA)
Mr G McIlroy (NIDARD)

Mr C R Mylchreest (Administrative Secretary)
Dr P E Cook (Scientific Secretary)
Mrs E A Stretton
Miss C L Wilkes

1. Chair's introduction

1.1 The Chair welcomed Members to the Committee's 48th meeting and extended a warm welcome to members of the public and others present (details at Annex I).

1.2 The Chair also welcomed Mr Mepham to this, the first ACMSF meeting since his appointment on 1 April 2003. The Chair said that Mr Mepham would be providing the Committee with environmental health expertise.

1.3 The Chair welcomed Dr Cook who had joined the Secretariat as Scientific Secretary, and Dr Hilton who, having been appointed Head of the Food Standards Agency (FSA)'s Microbiological Safety Division, was now present as the FSA headquarters Assessor.

2. Apologies for absence

2.1 Apologies were received from Ms Lewis and Dr Wyatt (absent for medical reasons), and from Ms Davies, Professor Gasson, Professor Humphrey, Professor Hunter, Professor Johnston and Mr Piccaver.

2.2 Apologies were also received from the FSA/Scotland Assessor, Dr Pryde.

3. Declarations of interest

3.1 In relation to agenda item 9, Dr Andrews reported that he had recently been invited to join the Sustainable Organic Resources Partnership (SORP) at the Environment Agency. SORP aimed to facilitate the recycling of organic waste to land.

4. Minutes of the 47th meeting

4.1 Members approved draft minutes ACM/MIN/47 as a correct record of the previous meeting.

5. Matters arising

5.1 Members noted ACM/633 prepared by the Secretariat on matters arising from previous meetings.

6. Avian Influenza

6.1 At the Chair's invitation, Dr Hilton introduced tabled paper ACM/634 providing an update on the outbreaks of Avian Influenza (AI).

6.2 Dr Hilton recalled that, at its previous meeting, Members had considered a paper (ACM/631) seeking the Committee's advice on the risk to human health through food chain exposure pathways from strains of AI. The Committee's preliminary conclusion had been that the risk was probably very low, but Members supported the suggestion that the ACMSF's member with virological expertise, Dr Brown, should consult experts in the field and prepare a formal risk assessment for their consideration. Dr Hilton said that the burden of additional work generated by the Severe Acute Respiratory Syndrome (SARS) outbreak had, in the event, prevented Dr Brown from completing this work, although he had spoken to relevant experts in both the human and veterinary fields.

6.3 Dr Hilton said that the AI position had now eased considerably. There had been no new cases on commercial poultry farms since the end of April, and trade restrictions were gradually being lifted. A number of cases of human conjunctivitis had been associated with exposure to H7 AI strains as a result of the outbreaks.

Partial sequencing of the internal genes of the virus circulating in the Netherlands suggested that the virus had not acquired genes which would enable it to cause significant disease in humans or allow person-to-person spread. However, a veterinarian who had visited an infected farm in the Netherlands had died from acute respiratory distress syndrome in April 2003. He had not been receiving viral prophylaxis (anti-virals/vaccination). There appeared to be no underlying reasons why he had developed systemic illness and there had been no other similar cases.

6.4 Dr Hilton said that the decline of the epidemic in the Netherlands had rendered completion of a risk assessment less pressing, but it was hoped that this would be available for consideration by the Committee at its next meeting, on 18th September. Current understanding was that mutation of AI from low to high pathogenicity was rare, but there was concern that this seemed to have happened more frequently in recent years.

6.5 Dr Brown agreed that ACM/634 broadly reflected events. There had been two recent H7 outbreaks in poultry, one (H7N1) in Italy and one (H7N7) in the Netherlands. No human health problems had been associated with H7N1 strains, in contrast to the cases seen with H7N7 strains. There were fifteen H types of influenza described in avian species and there was a considerable volume of literature to be reviewed. Work would continue on the development of a risk assessment, although quantifying risk was likely to prove extremely difficult. A serotypical study of those in direct contact with birds and their fomites had shown no evidence of AI infection in the population. The chances of the virus getting into the food chain seemed remote and there seemed no need for urgent action to protect human health on the basis of current knowledge.

6.6 The Chair thanked Dr Hilton and Dr Brown for the information provided. He said that the Committee would await a further progress report on the development of a quantitative risk assessment but, in the meantime, could continue to be optimistic about the remote risk of human exposure to AI through the food chain.
Action : Dr Brown

7. Severe Acute Respiratory Syndrome (SARS)

7.1 At the Chair's invitation, Dr Hilton introduced ACM/635 which provided an assessment on the risk to human health from SARS. The pandemic now seemed under control, new cases were down to 1-2 a day, and few travel restrictions remained in place.

7.2 Dr Hilton said that, although there were many coronaviruses which affected animals and humans, there was little evidence of zoonotic transmission. Recent investigations had identified a closely-related virus in, inter alia, civet cats in a live animal market in South China, but civet cats from other markets and in the wild had tested negative. It was thus possible that the affected civet cats had been infected from an unknown animal or human source. Infection from humans to animals seemed unlikely on the basis of the virological evidence, and the source of infection was still being sought. The epidemiology suggested that, even if the virus was zoonotic in origin, the principal transmission route was human-to-human spread via aerosols. Diarrhoea had been a feature of some cases and contaminated sewage, with subsequent aerosolisation of the virus, was the putative route in one case.

7.3 Dr Hilton said that, whilst the virus might have an animal reservoir, it was unable to infect pigs or poultry and appeared to be very different from coronaviruses found in other food animals. It was thus considered extremely unlikely that it would be present in meat from food animals. While it could persist in the environment, the virus was susceptible to heat (it was rapidly killed at 56¿C) and would be destroyed by proper cooking. In conclusion, Dr Hilton said that the risk of SARS being transmitted through food chain pathways seemed remote, but the possibility would be kept under review. Dr Brown agreed that food seemed unlikely to constitute a significant transmission route for SARS.

7.4 In subsequent discussion of the paper, the possibility of contaminated irrigation water being a possible transmission route was raised. It was also noted that, while cooking was an effective control point for the virus, the global market for ready-to-eat fresh produce raised the possibility of other exposure routes.

7.5 In thanking Dr Hilton for her presentation, the Chair asked that the Committee should be kept informed of any noteworthy future developments.
Dr Hilton (as necessary)

8. Clostridium botulinum guidance

8.1 At the Chair's invitation, Dr Cook introduced ACM/636 about advice on the bottling of vegetables in oil in the domestic and commercial settings.

8.2 Dr Cook recalled that, in March 2002, the ACMSF had commented on standard FSA advice on the risk of botulism associated with the home bottling of vegetables in oil (ACM/562). ACMSF Members had asked the Agency to recast its advice to reflect their comments, and to extend the advice to cover commercial production of these foods.

8.3 Dr Cook said that vegetable-in-oil products appeared to be popular and were likely to have been produced for hundreds of years to flavour cooking oils for use in foods . They were relatively new to Northern Europe but had long been popular in Southern European countries. Many different types of vegetables, herbs and spices, were added to oil. There were reported cases of botulism associated with the consumption of such products, manufactured both commercially and in the home. The most recently reported incident concerned a garlic in chilli oil product produced commercially in Germany which was associated with a case of botulism in a man in Denmark.

8.4 Dr Cook said that the FSA's current advice was that the home bottling of products in oil should be avoided. The Agency's advice to commercial manufacturers was that these products could be safely produced provided they were formulated to prevent germination and growth of Clostridium botulinum. This meant reducing the water activity to below 0.94 or the pH to below 4.6. In the absence of these controlling factors, storage at refrigeration temperatures was not regarded as sufficient to prevent germination and growth.

While growth of Cl. botulinum did not occur below 3.3¿C, domestic refrigerators could not be guaranteed to maintain this temperature. Dr Cook said that ACM/636 posed the question whether consumers should be advised that, if they complied with commercial controls on water activity and acidity, they could safely make products in oil in the domestic setting. It was also suggested that consumers making these products should be advised to use them immediately and throw away any leftovers. The Committee's views were also sought on the best medium through which to promulgate consumer advice.

8.5 The Chair reiterated that botulism was extremely rare in the UK as a cause of illness but, when it did occur, it could be extremely serious and was associated with a significant fatality rate. He invited Members comments on ACM/636. Among the points made in discussion were that :-

  • it seemed unlikely that anyone bottling products in oil in the home would consume them immediately and discard what was left. More practical advice might therefore be to consume within an appropriate time period on the day of production; to refrigerate, within an appropriate time period on the day of production, any product not consumed; and to consume or discarded it within one week of production;
  • greater attention should be given to the role of the oil in bottled products and why its use gave cause for concern (ie. in excluding air, it could potentially encourage the growth of any Cl. botulinum present in the product being bottled);
  • it was important that products being bottled should be dry. Placing wet vegetables in oil would be a good means of encouraging the growth of any Cl. botulinum present;
  • some commercial manufacture might be based on cottage industries where awareness of technical terms might be poor. Therefore, technical requirements needed to be framed in terms more readily comprehensible to non-technical audiences (eg. advice on water activity might be better framed in terms of brine strength);
  • temperature control should not be dismissed as a factor for controlling growth of proteolytic strains of Cl. botulinum, or reducing the growth rate of non-proteolytic strains, but it was essential that refrigerators were operating at the correct temperature;
  • it would be worth targeting “celebrity chefs” and those producing cookery books who regularly promoted products in oil. It was also important to bear in mind that many caterers infused oil and left it at ambient temperatures for many days;
  • a route of communication to cottage industry bottlers might be regional food distributors.

    8.6 The Chair thanked Dr Cook for his presentation and hoped that the FSA would be able to take account of Members comments in further developing their advice.

    9. Microbiological risk assessment

    9.1 The Chair reminded Members that the ACMSF had, at the request of Government, and through a specially-convened Ad Hoc Group, peer reviewed the microbiological aspects of a risk assessment carried out on the agricultural use of sewage sludge.

    9.2 More recently, the FSA had sought the Committee's assistance on similar risk assessments performed for the agricultural disposal of composted catering waste containing meat, and farmyard manures, slurries and abattoir wastes. These latter risk assessments had also been considered by the Ad Hoc Group which was now seeking ACMSF endorsement of its advice. The Chair invited Mr Kyriakides (deputising for the Group's Chair, Dr Wyatt) to present the 2 risk assessments.

    (a) composted catering waste containing meat (ACM/637)

    9.3 Mr Kyriakides said ACM/637 summarised the Ad Hoc Group's conclusions on the report of the risk assessment. The risk assessment had considered human health implications and the impact on animal health. The Ad Hoc Group had considered the former element only. The organisms addressed in the risk assessment were Campylobacter, E. coli O157, Salmonella and Clostridium botulinum. The health risk was assessed in relation to the consumption of soil from, or crops grown on, treated land.

    The risk was generally low, although a little higher for E. coli O157. However, the risk from that organism was estimated to be >5,000-fold lower than for manures and >40-fold lower than for treated sewage sludge. The main health risk from Cl. botulinum was judged to be infant botulism from spores remaining in composted material. The risk assessment report recommended that compost produced from catering wastes containing meat should carry a warning label designed to ensure that infants were not exposed to it.

    9.4 Mr Kyriakides said that the Ad Hoc Group regarded the approach adopted for the risk assessment as sound. The Group also regarded as acceptable the conclusion that, if the conditions specified for composting and biogas treatment were complied with, then the risks to human health would be very low. However, the Group had a number of observations which were detailed in paragraph 7 of the paper and which it proposed should be sent to the FSA for onward transmission to DEFRA. The ACMSF was asked to endorse the Group's observations and proposals.

    9.5 In discussion of the paper, the following points were made :-

  • basing the risk assessment on the consumption of 1 gram of compost was intended to represent an extreme case;
  • unless meat intended for human consumption by-passed statutory meat inspection procedures, it was unlikely that tapeworm would be present in catering waste;
  • pork would give a truer representation of risk than bacon (because the microbiological growth potential was higher), but the use of bacon might reflect the data available to the contractor. It was in any event noted that the contractors had in practice assumed fairly significant growth in bacon;
  • against a background of farmers developing composting businesses, it did not seem realistic to expect that raw catering waste material would be excluded from livestock farms;
  • equally, it would be very difficult to prevent birds and small mammals gaining access to the raw material;
  • the importance of eliminating any by-pass of the composting/biogas process should be stressed. In the risk assessment, the overall reduction of infectivity in meat in catering waste by composting was estimated to be 4.62-logs. However, it was estimated that 1% by-pass of the 4.62-log barrier process served to reduce the net removal from 4.62-logs to 2.0-logs (ie. the relative risks were increased by over 400-fold).

    9.6 Members agreed that an ACMSF response should go to the FSA based on ACM/637 and the additional comments made by Members.
    Action : Secretariat

    (b) animal manure and abattoir waste (ACM/638)

    9.7 Mr Kyriakides introduced ACM/638 summarising the Ad Hoc Group's comments on the animal manure and abattoir waste risk assessment. The risk assessment had been carried out by the same contractor responsible for the risk assessments on sewage sludge and catering waste. In performing the risk assessment, account had been taken of draft FSA guidance for farmers on Managing Farm Manures for Food Safety, the aim of which was to minimise the risks of microbiological contamination of ready-to-eat crops.

    The contractor had concluded that a disposal strategy involving on-farm storage of farm yard manure and slurry for prescribed minimum periods could form an effective barrier to the transfer of pathogens to crops or grazing livestock. However, the main concern was with the lack of robust microbial decay data on which to base the risk assessment.

    9.8 Mr Kyriakides said that the Ad Hoc Group regarded the report of the risk assessment as well structured and well presented, and regarded the approach taken by the contractor as sound, given the available data. However, the Group had a number of observations, detailed in paragraph 10 of the paper, which Mr Kyriakides explained to Members. The Committee was asked to indicate that it was content both with the Ad Hoc Group's analysis and for the comments in ACM/638 to be conveyed to the FSA on behalf of the ACMSF.

    Mr Kyriakides also drew attention to the contractor's assumption that there was little likelihood of animal viruses being present in manures, slurries and abattoir waste and thus no reason to include them in the risk assessment. This assumption had appeared to the Ad Hoc Group to be dubious (particularly in the case of abattoir waste). The views of Members would be welcome.

    9.9 The following points were made In discussion of the paper :-

  • given the variability of available data, the contractor had used best and worst estimates of die off. This gave large variations in estimates of crop contamination. The Ad Hoc Group had argued for the most pessimistic assumptions to be used. The limitations of quantitative risk assessment in the absence of robust data needed to be understood;
  • potential process by-pass was a concern, as in the case of catering waste. It would be extremely difficult to ensure compliance with any guidance provided;
  • injection, especially of abattoir waste, would be difficult to carry out without material becoming quite widely disseminated;
  • farmyard manures and abattoir waste would contain many viruses and this certainly needed to be reflected in the risk assessment.

    9.10 An Assessor drew attention to the likely economic impact of what was proposed. UK producers could be placed at a competitive disadvantage unless similar requirements were introduced across the European Union (although some Members States already applied more robust controls on the agricultural disposal of organic wastes). The Chair said that the ACMSF had been asked to peer review the microbiological aspects of the risk assessment. The wider economic and political implications would need to be addressed within Government.

    9.11 Members agreed that a response in the terms outlined in ACM/638 should go to the FSA. This made clear that there were still large holes in the risk assessment and that further work was required before it could be confidently used as the basis for taking policy decisions and developing meaningful guidance.
    Action : Secretariat

    10. Campylobacter Working Group

    10.1 The Chair introduced ACM/639, a progress report on the work of the Campylobacter Working Group. He said that the aim was to continue to develop the Group's draft report through the summer with a view to putting a draft to the full Committee at its meeting on 18 September 2003.

    10.2 The Chair asked all those members of the full Committee who were also members of the Campylobacter Working Group, and who were preparing contributions to the draft Campylobacter report, to send these to the Secretariat as soon as possible. Action : Members

    11. Horizon scanning

    11.1 The Chair recalled that the ACMSF had held a number of very full discussions on the question of horizon scanning and had set up Ad Hoc Groups to scope three particular areas – imported foods, changing social habits and newly-emerging pathogens – and to advise the full Committee whether further work was required. He invited those concerned with the Groups to provide oral progress reports.

    11.2 Mr Kyriakides (in the absence of Ms Davies, Chair of the Imported Foods Group) reported that the Group had met in March to scope its work and consider sources of useful information. The Group had received a presentation from the FSA's Imported Food Enforcement Branch on why it had been created and how it was working, in cooperation with HM Customs and Excise and DEFRA. The Group had agreed that it should consider both legal and illegal imports and had identified as an important area for consideration the means, if any, which existed in particular exporting countries for identifying the potential risks from pathogens.

    11.3 Mr Kyriakides said that the Imported Food Group hoped to meet again shortly when it would receive presentations, from the Health Protection Agency on the perceived risks from imported foods and the countries of origin of key importance, and from the FSA on traceability. Attempts were also being made to identify appropriate contacts in Customs and DEFRA who could speak to the Group about their work on food imports. The Secretariat was using the Internet to obtain information about how other countries (like the USA) tackled the question of the microbiological safety of food imports. Group members were seeking similar information from their EU counterparts.

    11.4 Dr Andrews, Chair of Changing Social Habits Group reported that the Group had held one meeting at which members had begun the process of identifying those areas where changing social habits could be expected to have a significant impact on food safety. Areas identified included out of home eating, loss of domestic culinary skills, travel abroad, and changing demographics. A list of key questions had been identified and work was now in hand to determine whether data existed to enable these questions to be answered. Dr Andrews said that, as part of this process, he had met with FSA economists and statisticians. Requests had also gone out to a number of ACMSF members to supply information. Dr Andrews said that the Group would meet again in September to review progress on the information-gathering process. He hoped that the Group would be in a position to report to the full Committee by the end of 2003. Finally, Dr Andrews said that, where risks identified related to imported foods, these would be dealt with by the Imported Foods Group, to avoid duplication of effort.

    11.5 It was agreed that the list of key questions to be addressed by the Changing Social Habits Group should be sent to all ACMSF Members who might then be in a position to identify data sources. Action : Secretariat. ACMSF Members should send any information they had to Dr Andrews or to the Secretariat.
    Action : Members

    11.6 In the absence of Professor Hunter (Chair of the Newly-emerging Pathogens Sub Group), Professor Georgala said that some further discussion was needed to define more precisely the remit of the Group. A progress report would be made to the Committee in due course.
    Action : Professor Hunter

    12. Dates of future meetings

    12.1 Members noted ACM/640 giving the dates and venues of future ACMSF meetings in 2003 and 2004.

    12.2 It was noted that the next meeting would be held on 18 September 2003 in Aviation House; and that all of the Committees quarterly meetings were now open to members of the public.

    13. Any other business

    13.1 Mr Gayford reported that the 2001 Report on Trends and Sources of Zoonotic Agents in the EU and Norway had now been published. This included much useful data on, eg., Salmonella, Campylobacter, E. coli, Trichinella, Brucellosis and Tuberculosis. The Report was available electronically. There were also 3 volumes of data from individual Member States, although this information was not published and could only be supplied publicly with the agreement of the Member States themselves. In response to a question from a Member, Mr Gayford said that he did not know whether the Trends and Sources document was available on CD-ROM but would make enquiries. Action : Mr Gayford

    13.2 Dr Andrews made 2 comments on the FSA's draft Campylobacter strategy (ACM/648) which had been provided for Members' information. He felt that, given that this was a consultation document, the reference (in paragraph 1.1) to the Belgian dioxin crisis would mean little or nothing to many readers and required further elaboration. He also took issue with the arithmetic in paragraph 1.5 of the strategy document. It had been assumed that half of the 800 million chickens produced in the UK each year were Campylobacter-positive and that a 5% reduction in Campylobacter levels would prevent 20 million positive birds from entering the kitchen. This was spurious because it was not the case that total annual UK chicken production went into domestic kitchens.

    14. Public Question and Answer session

    14.1 The Chair invited members of the public and others present to ask any questions or raise any points they might have.

    14.2 Mr Alan Long (VEGA) sought clarification of whether food waste containing meat could be fed to food animals. He identified an association between the consumption of poultry litter (often containing poultry carcass material) and botulism in cattle. He pointed out that poultry litter was sold through garden centres and he felt that it should be more strictly controlled. He had recently attended a public meeting of the Spongiform Encephalopathy Advisory Committee (SEAC) at which the DEFRA representative seemed prepared to countenance the relaxation of controls on the disposal to agricultural land of specified risk material. He regarded this as dangerous in the light of research from New Zealand showing that cattle could consume up to ¿ tonne of soil during the course of a year.

    14.3 In response, it was confirmed that it was now illegal to feed any food waste containing meat to food animals. The ban included feeding poultry carcasses to ruminants. It was acknowledged that poultry litter spread on pasture as manure had been associated with cattle botulism. DEFRA had alerted the FSA who had taken action to protect the food chain. The ACMSF was acutely aware of the complex patterns of disposal and utilisation of waste associated with livestock production and was taking the required steps to draw Government's attention to areas of concern, notably as part of the Committee's peer reviewing of the risk assessments performed for the various waste streams.

    14.4 Mr Long also drew attention to the risks associated with eating on public transport. He felt that there should be warnings that this practice was unhygienic. He also felt that public toilets in restaurants etc should have lids to prevent the dissemination of contamination via aerosols. He also regarded the use of hot air hand dryers as a further means by which contamination could be spread.

    14.5 The Chair said that the Committee's Ad Hoc Group on Changing Social Habits would doubtless bear these thoughts in mind. He also noted that the FSA was maintaining a strong focus on food hygiene, including in the catering setting.

    Annex I - list of members of the public and others attending the ACMSF'S 48th meeting
    Mr Alan Long - VEGA
    Ms Gemma Mulholland - DEFRA
    Mr Martin Rogers - Reading Scientific Services Ltd
    Dr Bernard Rowe
    Dr Roger Skinner
    Mr Ian Smith - FSA
    Mr Shaun Whelan - FSA