Putting Principles into Practice: Useful Case Studies

1. Putting Principles into Practice:Useful Case Studies Amir Mokhtari, Ph.D. Dubai International Food Safety Conference, February 24-26, 2009 Dubai, UAE 701 13th Street, N.W., Suite 750, Washington, DC, 20005, USA E-mail: amokhtari@rti.org Phone: (202) 728-1973 Fax: (202) 728-2095

2. We are going to talk about… • Challenges facing food safety authorities • What we mean by risk analysis • How risk analysis can be used • How risk analysis can improve decisions • Microbial risk assessment (MRA) and food safety • MRA Case Study #1: L. monocytogenes • MRA Case Study #2: Norovirus transmission • Concluding remarks

3. What are the challenges facing food safety authorities? • Rapidly growing volume and diversity of food trade • Changing agricultural practices, production and manufacturing systems, food handling patterns, etc. • New and emerging food-borne hazards • Effect of climate change on the food supply • New food and agricultural technologies • Greater public demands for health protection • Requirements of sanitary and phyto-sanitary measures to be based on science and risk assessment

4. What is risk analysis? • Risk assessment- science-based tasks of measuring and describing the nature of the risk being analyzed • Risk management- defines the problem, articulates the goals of the risk analysis and identifies questions to be answered • Risk communication- interactive exchange of information among risk managers, risk assessors, consumers and other stakeholders

5. How is risk analysis used? • To predict the likelihood of exposure to harmful agents that result in an adverse human health outcome • To prioritize food-related threats to public health in support of the decision-making process (e.g., resource allocation) • To identify points along the food supply chain that contribute to the public health risk • To evaluate and rank mitigation options and strategies with respect to human health outcomes • To provide the scientific and technical basis needed to develop risk management strategies • To communicate with stakeholders about the risks and measures applied

6. How does risk analysis improve the decision-making process? • Support decisions that are in proportion to public health risks involved • Enable systematic evaluation of likely impacts of measures selected to manage risks • Allow likely costs of compliance to be compared with expected benefits • Provide a useful metric in prioritizing different food safety problems • Meet obligations under international agreements and enhance trades • Identify gaps and uncertainties in scientific knowledge to help set research priorities

7. Microbial risk assessment (MRA) and food safety MRA is performed for pathogen/food combinations that may be associated with food-borne illness (single pathogen, one product, the entire supply chain)

8. Basic Components of an MRA

9. Microbial risk assessment covers the farm-to-fork continuum Microbiological Risk Assessment can be applied to each individual step in a (typical) food supply chain, from primary production to consumption (single pathogen, one product, all supply chains)

10. MRA Case Study #1:L. monocytogenes in Deli Meats • FDA/USDA examined the effectiveness of testing and sanitation of food contact surfaces to reduce product contamination and risk of illness • Provided guidance on how frequently to test and sanitize food contact surfaces for Listeria spp.

11. FDA used MRA to rank LM risks of Ready-to-Eat (RTE) products • Approach: relative risk ranking of food categories • Purpose: identify the food category with the greatest public health risk • Key finding: deli meats pose the highest risk, and hence, deserve the focus

12. MRA Model Applied to the High Risk Category – Deli Meats • An “in-plant” model that predicts LM concentrations at retail • Coupled with an updated version of the FDA Listeria model to predict human health impacts • Track bacteria as they move from one media to another • Incorporates FCS testing, product testing, sanitation, pre- and post-packaging interventions, growth inhibitors, etc.

13. MRA Model Provided Important Information on Interventions • Positive food contact surfaces for Listeria species greatly increased the likelihood of finding positive RTE product lots • Minimal testing frequency of food contact surfaces will only result in a small reduction in the levels of contamination at retail • Increased frequency of food contact surface testing and sanitation can reduce the risk of listeriosis • Combinations of interventions appear to be much more effective than any single intervention

14. Based on the MRA, Alternatives Were Developed to Reduce Risk • Alternative 1 – Employ both a post-lethality treatment and a growth inhibitor for Listeria on RTE products. Establishments opting for this alternative will be subject to FSIS verification activity that focuses on the post-lethality treatment effectiveness. • Alternative 2 – Employ either a post-lethality treatment or a growth inhibitor for Listeria on RTE products. Establishments opting for this alternative will be subject to more frequent FSIS verification activity than for Alternative 1. • Alternative 3 – Employ sanitation measures only. Establishments opting for this alternative will be targeted with the most frequent level of FSIS verification activity.

15. Case Study #2: Transmission of Noroviruses by food handlers • Leading cause of food borne disease • Poor handling practices of infected food handlers are responsible for the majority of infection cases • No available study on the behavior of human noroviruses in food preparation environments • No available systematic MRA exercise with a focus on poor handling practices

16. Designed a MRA with Specific Management-Related Goals in Mind • Investigate the behavior of enteric viruses in the food preparation environment • Investigate the role of poor personal hygiene in transmission of enteric viruses • Incorporate the behavioral factors to evaluate control strategies aimed at food handling

17. How virus particles are transferred in a food preparation environment

18. Representing reality using a mathematical model

19. Considered Scenarios that were Relevant to Control Strategies • Changes in: • Employee’s behavior • Sanitation practices • Persistence and inactivation of virus particles • Cross-contamination sources: • Hands and gloves of an employee • Food contact surfaces • Time component: • Food preparation • Sanitation practices • Visiting bathroom

20. Model Results

21. Hand washing versus gloving: which one is a more effective way to control risk? • Even with 100% hand washing compliance, at least 30% gloving is required to limit the contamination level below the critical level • With observed hand washing compliance in food establishments (e.g., ~60%), at least 65% gloving compliance is required to limit the contamination level below the critical level Critical Level: minimum number of viral particles that is sufficient to infect an individual

22. Hand washing efficiency versus hand washing compliance: which one is more important? • Even with 3 log10 hand washing efficiency, hand washing compliance of 80% was required to limit the contamination level below the critical level • High inactivation efficiency (3 log10) could not entirely ensure product safety given the observed hand washing compliance in food establishments (i.e., <60%) • With 100% compliance, inactivation rate of approximately 0.7 log10 (i.e., 80%) still required Critical Level: minimum number of viral particles that is sufficient to infect an individual

23. Fecal contamination versus restroom contamination • Frequent cleaning of the restroom environment is an effective way to control the transmission of Norovirus particles to food products • Low environmental contamination ensured up to 95% of food products with contamination levels less than the critical level • In contrast, food products were highly contaminated for scenarios in which the restroom environment was highly contaminated Critical Level: minimum number of viral particles that is sufficient to infect an individual

24. MRA Model Provided Important Information on Control Strategies • NoV show persistence on environmental surfaces (and hands) and are transferred with relative ease • Current alcohol-based hand sanitizers (70%) do not appear efficacious for control of the NoV • Even with less than perfect data, a preliminary exposure model for the transmission of NoV in the food preparation environment was feasible • The model is most sensitive to factors impact degree of virus shedding and to food handler behaviors • There is an important interplay between compliance with recommended hygiene practices and virus removal (inactivation) efficiency

25. Concluding Remarks • Risk assessment is a powerful tool for evaluating strategies to reduce disease and for prioritizing future research needs • Because we can not “inspect our way to food safety,” risk assessment should be an integral part of food safety policy • Scientists, risk managers, and policy makers need to work together to develop a food safety system that is both responsive and proactive in addressing threats to our food supply

26. Acknowledgements • Collaborators • Steve Beaulieu (RTI International) • Dr Lee-Ann Jaykus (North Carolina State University) • Dr. Christine Moe (Emory University) • Dr. Jan Vinje (CDC)