Putting Principles into Practice: Useful Case Studies

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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_at_rti.org
Phone [phone] Fax [phone]
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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

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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

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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

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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

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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

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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)

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Basic Components of an MRA
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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)

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MRA Case Study 1L. 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.

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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

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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.

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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

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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.

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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

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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

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How virus particles are transferred in a food
preparation environment
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Representing reality using a mathematical model
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Considered Scenarios that were Relevant to
Control Strategies

• Changes in
• Employees 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

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Model Results
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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
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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., lt60)
• 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
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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
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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

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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

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Acknowledgements

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