ACMSF Minutes: 29 May 2012

Meeting held at 1pm in Aviation House, 125 Kingsway, London WC2B 6NH


Professor Sarah O’Brien

Dr Bob Adak
Mr John Bassett
Dr Roy Betts
Mrs Vivianne Buller
Mrs Rosie Glazebrook
Professor Jim Gray
Dr Rick Holliman
Ms Jenny Hopwood
Professor David McDowell
Mr Paul McMullin
Dr Sally Millership
Mr David Nuttall
Professor Peter Williams

Departmental representatives:
Mr Stephen Wyllie (Defra)
Ms Liz Redmond (FSA)

Officials in attendance:
Mrs Robyn Polisano (FSA)

Ms Geraldine Hoad (Administrative Secretary)
Dr Paul Cook (Scientific Secretary)
Mr Adekunle Adeoye
Dr Sophie Rollinson

Invited Experts:
Dr Nicola Holden (John Hutton Institute)
Ms Joy Dobbs (SSRC Deputy Chair)

Fiona Brookes, 2 Sisters Technical Services
Keneth Chinyama, Food and Drink Federation
Bridgette Clarke, Bakkavor
Kaarin Goodburn, Chilled Food Association
Waheed Hassan, Booths
Intisar Khan, Dairy Crest
Barry Mirhabib, Brakes
Melanie Patterson, Life Technologies
Rick Pendrous, Food Manufacture magazine
Bernard Rowe
Karen Sims, Waitrose
Theresa Taylor, Radisson Edwardian Hotels
Sian Thomas, Fresh Produce Consortium
Nicola Wilson, Westward Laboratories
Yvonne Stedman, Sainsburys

1. Chair's Introduction

1.1 The Chair welcomed ACMSF Members, members of the public, Dr Nicola Holden, Ms Joy Dobbs and Mrs Robyn Polisano to the Committee’s 78th meeting.

2. Apologies for absence

2.1 Apologies for absence were received from Mrs Jenny Morris and Professor John Coia.

3. Declarations of interest

3.1 The Chair reminded Members of the need to declare any conflicts of interest relating to items on the agenda. Dr Betts declared an interest in relation to item 6 as Campden BRI, his employer, have members who produce and market fresh produce. Mr Bassett declared an interest in relation to item 9 as his employer Unilever, sell products containing meat. Prof McDowell declared an interest in relation to item 8 as he had received funding from Safefood to carry out research on food safety behaviours in the home. Members were reminded to raise any other declarations of interest if the need arose during discussions.

4. Minutes of the 77th meeting (ACM/MIN/77)

4.1 The minutes were accepted as an accurate record of the last meeting and the Secretariat was asked to publish them on the ACMSF website.
Action: Secretariat

5. Matters arising (ACM/1063)

5.1 Ms Hoad drew Members’ attention to the summary of actions taken on matters arising from previous meetings, all matters had been actioned. Specific feedback was provided on the ACMSF’s risk assessments on M. bovis and raw drinking milk which had been included in a paper to the FSA Board on the safety of raw drinking milk. The Board had agreed that the options for managing the food safety risks should be reviewed and advice for Ministers formulated.

6. Internalisation of pathogens by fresh produce (ACM/1064)

6.1 Ms Hoad introduced this agenda item explaining that outbreaks of foodborne disease which had been linked to fresh produce had raised questions on the possibility of internal colonisation of produce by pathogens. This topic had been the subject of several reviews previously, including by FAO/WHO who had concluded there was no evidence to indicate that internalisation was significant in practice. They noted however, that data on non-experimentally induced infection under Good Agricultural Practice was limited. Two further reviews on the mechanisms, routes and factors influencing pathogen internalisation were summarised. Ms Hoad explained that the FSA is considering further work on the uptake and persistence of pathogens in plants in commercially relevant growth cycles. ACMSF views were therefore being sought on the need for further research to establish the implications for consumer health and the key evidence gaps.

6.2 Dr Nicola Holden from the James Hutton Institute was invited to give a presentation on pathogen internalisation by fresh produce and recent research on this topic. Dr Holden summarised current evidence for internal colonisation of produce by pathogens and highlighted some international outbreaks of illness associated with sprouts, noting the pathogens most commonly involved. The mechanisms of internalisation, colony formation and localisation of internalised bacteria were also presented. Dr Holden summarised her recent research on internalisation of Enterohaemorrhagic E. coli (EHEC) in lettuce and spinach roots and leaves and gave details of other research groups working in this area. The strengths and weaknesses of the existing body of research on pathogen internalisation were highlighted, including the major knowledge gaps. Potential factors that may increase the risk of internalisation were also suggested. Dr Holden concluded that internalisation can occur but is rare and varies depending on factors such as plant species, bacterial species, how plants are grown and plant health. The risks from internalisation via roots appear to be low and there is no apparent correlation between internalisation in roots and presence in edible foliage, although further work is needed to confirm this.

6.3 The following comments and questions were raised by Members in the ensuing discussions:

  • The reason for the difference in bacterial uptake with high and low inoculum levels was queried. Dr Holden responded that studies had shown bacteria on compost could die quite easily, particularly with high inoculums, reaching a threshold level where they may eventually become viable but non-culturable. One study had shown colonisation with viable, non-culturable bacteria was possible where viability was recovered. It was not clear if this was happening with the low inoculum levels.
  • It was asked whether the internal colonies are due to bacterial growth or whether bacteria accumulate. Dr Holden explained that growth was definitely seen with an increase and then a plateau in bacterial numbers although the growth rate was not known.
  • In response to a query on what work had been done to look at virus internalisation and viability Dr Holden responded that some studies had looked at internalisation and presence of surrogate viruses but virus presence was only detected using PCR and therefore viability was not determined.
  • A member asked whether the fate of internalised bacteria after harvesting and storage of produce had been investigated as it was important to know whether the bacteria continue to grow. Dr Holden responded that this would probably depend on various factors but if produce was stored below the minimum growth temperature, bacterial growth was not seen. However studies had shown reactivation of bacterial growth after cold shock was possible. Bangor University are currently looking at this but there are not sufficient studies to give a definitive answer at present. Dr Holden also added that a study had shown that pathogens passaged through plants maintained their infectivity.
  • It was suggested that investigation of fresh produce linked to outbreaks, to try and determine whether the bacteria were internalised may provide useful information as this was not known at present. It was also suggested that further sampling of fresh produce would be useful to determine the true prevalence and concentration of internalised pathogens.
  • In response to a question on experimental practice Dr Holden confirmed she was confident that Gentamicin was sterilising the surface of experimental produce.
  • It was queried whether bacteria associated with hydroponics systems are generally planktonic whilst those associated with soil are in a biofilm. Dr Holden responded that some variation was seen in hydroponic populations but biofilms were predominant in soil. A correlation between motility and colonisation of plants had been noted but no correlation between biofilm formation and colonisation had been seen.
  • The relevance of experimental research to real life conditions and field studies was questioned, particularly in light of variation between plant types and effects of external conditions on plants. Dr Holden responded that fresh produce was often grown under hydroponic systems or protected conditions and so there was some relevance to experimental conditions.
  • The existence of pathogen risks to which consumers have not been previously exposed, from imported produce from non-temperate climates was raised. In was noted that outbreaks associated with food from other countries often involved multiple pathogens as the population had no existing immunity. It was also noted that the systems in countries where crops were grown for import to the UK were often very well defined. The mechanism by which seeds may become contaminated was highlighted as relevant and therefore traceability was considered an important consideration.
  • It was suggested that work to look at the effectiveness of current risk management strategies and their effectiveness at removing internal bacteria would be valuable.
  • The potential for synergies with ACAF was also highlighted in terms of seeds that may be used for animal feed.

6.4 The Chair summarised the research needs identified by the Committee. These included further work to determine the prevalence, concentration and viability of pathogens (including viruses) in fresh produce in both field and experimental conditions and research to look at the fate of these organisms after harvesting. It was also recommended that where fresh produce is implicated in outbreaks of disease it may be possible to investigate if pathogens had been internalised in the produce. Further investigations to look at variations with different species types, growth conditions and phenotypic response were also recommended.

7. ACMSF risk assessment (ACM/1065)

7.1 Dr Paul Cook was invited to present paper ACM/1065. Dr Cook noted that at its previous meeting the Committee had endorsed a framework for ACMSF risk assessment but had not had the opportunity to discuss the format or language used for risk assessment outputs. A wide range of terms and descriptors are currently used to characterise the level of risk and the uncertainty associated with a risk assessment and clear articulation of these is needed to avoid ambiguity. Adoption of a standardised approach by the Committee would improve the transparency and consistency of its assessments. A number of possible approaches for qualitative risk assessment outputs were outlined in paper ACM/1065. The Committee was asked if it wished to standardise descriptors used to convey risk estimates and uncertainty and, if so, which descriptors it would wish to use.

7.2 Members agreed that a consistent approach for outputs in terms of risk estimate and uncertainty was desirable and a simple, understandable system would be most appropriate. The importance of defining the model adopted by ACMSF was agreed but development of ACMSF’s own risk assessment terminology was not considered necessary. It was agreed that for clarity the full terminology selected for risk estimates and uncertainty should be published with each risk assessment produced.

7.3 It was suggested that in some cases estimates of uncertainty based on published scales appeared to be too precise. There was a danger of implying an excessive level of accuracy which could be misleading given the high levels of uncertainty associated with most risk assessments. It was agreed in most cases a subjective description of uncertainty would suffice.

7.4 Some members felt that use of numerical outputs for risk classification was more appropriate as these were more easily understood by consumers than terms such as low, medium and high. It was suggested that the tools used in clinical trials could provide some guidance. It was also suggested that the Committee should be guided by the approaches most likely to convey a clear idea of what the Committee means when developing outputs for risk managers.

7.5 Table 3 in paper ACM/1065 was unanimously selected by the Committee as most appropriate for the presentation of risk level classification. There was discussion over the most suitable approach for describing uncertainty. Some members felt table 4 (GRADE scale for quality of evidence) was more suitable as this described the quality of the evidence and was representative of the situation at the time of the risk assessment. It was suggested the text in the low quality descriptor should be altered from “further research…. is likely to change the estimate” to “further research…. may change the estimate”. Other members felt table 4 was a description of future research needs and table 2 was more appropriate as it described the uncertainty at the time the risk assessment was carried out and it was more compatible with the risk level classification system agreed. However it was also suggested table 2 was overly complex involving use of several parameters that may not always be available and was more suited for quantitative risk assessments.

7.6 The Chair summarised discussions, noting that table 3 had been chosen as the most appropriate for ACMSF risk level classification and tables 2 and 4 were most appropriate for describing uncertainty. The Chair suggested that applying different combinations of these approaches may be required in different circumstances and they should be applied in practice to see what works.

8. Update on Social Science Research (ACM/1066)

8.1 The Chair welcomed Mrs Robyn Polisano and Mrs Joy Dobbs, deputy Chair of the Social Sciences Research Committee (SSRC), to the meeting to provide an update on Social Science Research of relevance to ACMSF. Mrs Polisano gave an overview of the evidence review of food safety behaviours in the home which had originated from ACMSF’s request for work to help identify behaviours that might be putting the over 60s at risk of listeriosis. Mrs Polisano explained the work was relevant to a wider range of pathogens and population groups and highlighted the key findings. An update on wave two of the “Food and You” Survey was given. The survey measures public attitudes, knowledge and behaviours towards food over time. Some of the potential food safety risks highlighted from wave one included fridge temperatures, adherence to date labelling and washing of raw meat. A brief overview was given on the in-home kitchen practices study, which will use an ethnographic approach to look at kitchen practices in 18 UK households, and a quantitative survey on consumer attitudes to raw meat decontamination treatments. Mrs Polisano also highlighted SSRC’s paper on presenting uncertainty in risk assessments which provided some advice on practical issues, noting that SSRC were keen to engage with others to consider how some of the issues might be addressed early in any planned work.

8.2 The following questions and comments were made in discussions:

  • A Member queried how the 18 homes taking part in the kitchen practices research had been selected. Mrs Polisano explained that they were households that had responded to the Agency’s “Food and You” Survey that had indicated they would be happy to be involved in future research. It was acknowledged that these households and the results were not intended to be representative of the whole UK population but the aim of the work was to look in detail at practices in the home.
  • A Member highlighted similar work studying in-home food safety behaviours carried out by Safefood in Ireland. Different approaches to population sampling, methods for achieving a good response level and the limitations and challenges associated with behaviours research were discussed.

9. Risk profile in relation to toxoplasma in the food chain (ACM/1067)

9.1 Dr Rick Holliman presented paper ACM/1067, which summarised responses to the public consultation on ACMSF’s toxoplasmosis report. Dr Holliman explained that consultation replies received were listed in ACM/1067a along with the Working Group’s response. Responses received had been generally supportive and a number of revisions were made to the report to address suggested additions. These included additional text on neurological associations with toxoplasmosis, reference to a newly developed test to aid in distinguishing the route of infection and further emphasis on the need to consider immuncompetent individuals who may go on to become immcompromised in later life. Dr Holliman noted that a number of consultation responses related to risk management issues and these would be forwarded onto FSA. The Committee were asked to approve the consultation response and final report.

9.2 There were no questions or comments in relation to the report. The Chair therefore thanked the group for their work and noted the report could be formally handed over to FSA.
Action: Secretariat

10. Horizon scanning

10.1 The Chair reminded members that they had received a presentation at their last meeting on a snapshot survey of changing techniques in the hospitality sector that might impact on microbiological safety. It was agreed that a small group should take forward work on two areas identified as a concern; extrapolation of data on pathogen survival at low cooking temperatures and the microbiological safety of raw and rare foods. Dr Roy Betts, Chair of the group was invited to provide an update.

10.2 Dr Betts explained that the group had held a teleconference to discuss the approach, scope, timings, Terms of Reference and potential outputs for the work. They had agreed that establishing a formal Ad Hoc Group would facilitate working. The Group agreed that the issues under consideration were not restricted to the catering sector and the scope should be widened to include the domestic and hospitality sectors. The Group also agreed to focus on products of animal origin as they posed the main risk. The output would be a paper with recommendations and a presentation to the Committee. It was hoped the work would take 12 months. The Terms of Reference agreed by the Group were to assess the microbiological risks to consumers associated with use of low temperature cooking/slow cooking, foods of animal origin served raw, foods of animal origin served rare and to identify any gaps in the data that would assist in a risk assessment.

11. Committee sub-groups

11.1 Professor Sarah O’Brien provided a report on the Ad Hoc Group on Foodborne Viral Infections seventh meeting. The group had discussed measuring infectivity and infectious dose of norovirus, emerging virus risks, virus surveillance systems and their strengths and weaknesses and had received an update on the EU-wide VITAL project, looking at viruses in the food chain. The Group have now gathered all the evidence they need. A first draft of the report is planned for presentation at the January 2013 ACMSF meeting.

11.2 The Chair of the Newly Emerging Pathogens Working Group, Professor Peter Williams, was invited to report on the Groups’ consideration of Bovine Neonatal Pancytopenia (BNP). Prof Williams explained that the Group had met twice to consider the issue, in 2010 and in 2012 and in between these meetings a significant amount of new research had been published which was helpful to the group’s discussions. The Group had concluded that the microbiological risk through the food chain, associated with BNP was negligible. The principal hypothesis developed in the scientific community was that the disease had an immunological basis and the Group therefore considered the immunological risks, recognising they were at the limits of their remit and expertise. Prof Williams outlined the factors considered by the Group in assessing the levels of BNP associated alloantibodies that may be present in meat and milk. The Group concluded that, within the limits of their remit, the immunological risk to human health from BNP affected animals was very low but they recommended that their report is sent to a committee with the appropriate specific immunological expertise for consideration.

11.3 Members made two comments on the Group’s statement. It was suggested that the last paragraph on page 2 should clarify that the beef cattle lifespan referred to is the dam’s lifespan and the 4th paragraph on page 3 should refer to the calf’s gut rather than stomach. The Chair noted that the Group’s response would go back to the National Expert Panel on New and Emerging Infections (NEPNEI) who had forwarded the issue to ACMSF originally.

11.4 Dr Roy Betts updated the Committee on the recent work of the Surveillance Working Group. A meeting of the Group had not been held but Members had provided written comments to the Agency on the FSA’s draft protocols for forthcoming surveys on Campylobacter in chicken and Listeria in cooked meats. The comments will be used in further development of the surveys.

12. Dates of future meetings (ACM/1069)

12.1 Members were asked to note the date of the 2012 ACMSF meeting on 27 September and the 2013 meetings on 31 January, 27 June and 3 October.

13. Any Other Business

13.1 Prof O’Brien provided an update on the March General Advisory Committee on Science (GACS) meeting. GACS had received a description of the Rural Economy and Land Use (RELU) project, which was a 10 year programme of interdisciplinary research, combining natural and social sciences. The project has produced a number of reports and publications, including on E.coli O157 and risk perception.

13.2 The Chair also informed the Committee she had attended the FSA Board meeting in March to join discussions on the microbiological safety of raw milk, following ACMSF's risk assessment on this issue. The FSA are carrying out further work to look at the potential risk management strategies and the Committee will be provided with updates in due course.

14. Public questions and answers

14.1 The Chair drew formal proceedings to a close and invited questions and comments from the public. There were no questions.