Get documents about "Microbial Risk Assessment and Mitigation Workshop: towards a
Document Sample
MICROBIAL RISK ASSESSMENT AND MITIGATION
WORKSHOP: TOWARDS A QUANTITATIVE HACCP APPROACH
Moez SANAA & Ewen Todd
7th Dubai International Food Safety Conference
&
IAFP’s 1 st Middle East Symposium
on Food Safety
GENERAL INTRODUCTION TO RISK ASSESSMENT IN
FOOD SAFETY
Ewen Todd
7th Dubai International Food Safety Conference
&
IAFP’s 1 st Middle East Symposium
on Food Safety
DEFINITIONS OF RISK
Risk: a function of the probability of an adverse health effect and
the severity of that effect, consequential to a hazard(s) in food
Risk Analysis: a process consisting of three components: risk
assessment, risk management and risk communication
PURPOSE OF RISK ANALYSIS – CODEX ALIMENTARIUS
To identify methods to address food safety more effectively
To introduce appropriate food control measures
Risk analysis has become the cornerstone in developing food control
measures by linking epidemiological and laboratory findings with
modeling procedures to estimate risks and their mitigation
DIFFERENCE BETWEEN RISK ANALYSIS AND
HAZARD ANALYSIS - CODEX ALIMENTARIUS
Hazard analysis - addresses hazards within a narrow context,
such as the potential for the hazard to enter a food at a
plant/processing level. A hazard analysis is usually conducted
at the plant/process level to establish a HACCP plan
Risk analysis –also deals with hazards, as well as the condition
of a food; however, it does so on a broader scale by
examining the potential impact of a hazard that is introduced
into the food supply, taking into account exposure from other
sources
Material or
RISK ASSESSMENT situations, physical,
chemical, and or
RA is the qualitative or quantitative microbial agents
characterization or estimation of
potential adverse health effects
associated with exposure of
individuals or populations to hazards
Risk assessment
Not used in
isolation, but as a
part of Risk Analysis
Risk Risk
communication management
PURPOSE OF RISK ASSESSMENT
A systematic examination of an issue to help make
better risk management decisions
The risk manager should request the assessment to
respond to specific questions
RISK ASSESSMENT DEFINITIONS -CODEX
ALIMENTARIUS
Risk assessment – the scientific evaluation of known
or potential adverse effects resulting from human
exposure to foodborne hazards
Hazard
characterization
Hazard Exposure
identification assessment
Risk
Characterization
RISK ASSESSMENT DEFINITIONS -CODEX ALIMENTARIUS
Hazard identification – The identification of biological,
chemical and physical agents capable of causing adverse
health effects and which may be present in a particular food
or group of foods
Hazard characterization – The qualitative and/or quantitative
evaluation of the nature of the adverse health effects
associated with biological, chemical, and physical agents
which may be present in food
For chemical agents, a dose-response assessment should be
performed
For biological and physical agents, a dose-response assessment should
be performed if the data are available
RISK ASSESSMENT DEFINITIONS -CODEX ALIMENTARIUS
Exposure assessment – The qualitative and/or quantitative
evaluation of the likely intake of biological, chemical, and
physical agents via food as well as exposures from other
sources if relevant
Risk characterization – The qualitative and/or quantitative
estimation, including attendant uncertainties, of the
probability of occurrence and severity of known or potential
adverse health effects in a given population based on hazard
identification, hazard characterization and exposure
assessment
DEFINITIONS -CODEX ALIMENTARIUS
Risk management – The process, distinct from risk
assessment, of weighing policy alternatives, in consultation
with all interested parties, considering risk assessment and
other factors relevant for the health protection of consumers
and for the promotion of fair trade practices and, if needed,
selecting appropriate prevention and control options
Risk communication – The interactive exchange of
information and opinions throughout the risk analysis process
concerning risks, risk-related factors and risk perception,
among risk assessors, risk managers, consumers, industry, the
academic community and other interested parties, including
the explanation of risk assessment findings and the basis of
risk management decisions
RISK COMMUNICATION POINTERS - CODEX ALIMENTARIUS
Know the audience
Involve the scientific experts
Establish expertise in communication
Be a credible source of information
Share responsibility
Differentiate between science and value judgement
Assure transparency and put the risk in perspective
Effective communication is an integral component of the risk
analysis process and is often the least well done
WHAT RISK ANALYSIS TRIES TO ADDRESS
Risk Communication questions (science plus
economical, social and ethical values):
• Who are the stakeholders?
• What are we trying to communicate - information out
or input in?
• What level of technicality should be discussed -
assessors to managers/managers to other
managers/managers to the industry and public?
• How much time do we allow for this process?
• What degree of dialog do we allow?
• How much does risk perception of an issue affect the
communication process?
EXAMPLES IF RISK ASSESSMENT AND RISK MANAGEMENT QUESTIONS
Risk Assessment questions (science):
What could go wrong?
How likely is it to happen?
Who would be affected?
How severe would the consequences be?
What populations are affected?
What can we do that will reduce risk?
Risk Management questions (science plus policy issues):
What are the most effective and acceptable policies to reduce risk
to acceptable levels - choosing management options which may
include doing nothing?
When instituted, how well have these policies worked – implement
an evaluation and review process?
RISK ASSESSMENT IN RISK-BASED DECISION-MAKING
To support decisions, the objectives of RA are:
• Estimate the probability of a given consequence, event, or effect;
• Understand how and when such consequences may occur;
• Estimate the impact of the various consequences; and
• Evaluate the potential outcomes or consequences of selected
management options
Risk assessment is a tool to inform risk managers and policy makers about
risk management…
WHAT IS NEEDED?
• Timely, broadly based and
• Well informed, founded on the most reliable data,
accurate in the interpretation of data, and
• Transparent in the communication of results to
interested parties.
• With consideration and recognition of socio-political
context in which activities and decisions are
undertaken.
RISK ASSESSMENT CHALLENGES
Transparency: Characteristics of a process where the
rationale, the logic of development, constraints,
assumptions, value judgements, decisions,
limitations and uncertainties of the expressed
determination are fully and systematically stated,
documented, and accessible for review
Many risk assessors offer their peers a draft assessment
for comment before it is finally given to the risk
manager or for publication
Uncertainty Analysis: a method to estimate the
uncertainty associated with model inputs,
assumptions and structure/form
Data Variability: Assessments also include data that
are generated with small to large variability
RISK MANAGERS VS. RISK ASSESSORS
The risk manager determines the need for the assessment but
leaves the process to the scientific assessors
However, certain interactive elements are essential for a
systematic risk assessment process
include ranking of hazards in the hazard identification step
and consideration of possible management options
LIMITATIONS OF RISK ASSESSMENTS
Although a risk assessment must be soundly based
upon science, the amount of data available are often
very limited, and may they be conflicting, including
variability and uncertainty
Assumptions then may have to be made on the best,
informed judgements to the assessors
Good quality quantitative information is preferable
to qualitative data but there is often less of it
TYPE OF RISK ASSESSMENTS
Quantitative Risk Assessment (QRA): a risk
assessment that provides numerical expressions of
risk and indication of the attendant uncertainties
Qualitative Risk Assessment: a risk assessment based
on data, which, while forming an inadequate basis
for numerical risk estimations, nonetheless, when
conditioned by prior expert knowledge and
identification of attendant uncertainties permits risk
ranking or separation into descriptive categories of
risk
MICROBIAL RISK ASSESSMENT
WORLDWIDE PERSPECTIVE ON FOODBORNE DISEASE
The World Health Organization believes that hundreds of
millions of people worldwide suffer from diseases caused by
contaminated food, especially in developing countries
There is an estimated annual incidence of some 1.5 billion
episodes of diarrhea in children under five years of age
Over two million deaths and many of these diarrheal cases
are foodborne in origin
In the U.S. there are 48 million cases and 3000 deaths
annually (Scallan et al., 2011)
Main agents: norovirus, Salmonella, Clostridium perfringens,
Campylobacter, Staphylococcus aureus
MICROBIAL FOODBORNE PATHOGENS
Pathogen Implicated Foods Disease
Bacillus cereus Rice, vegetables, meat Mild: vomiting and diarrhea
Clostridium Stews, chili, etc. (anaerobic) Mild: cramps, diarrhea
perfringens
Salmonella Eggs, meat, fruit, juices, Moderate: GI symptoms,
spices, chocolate, etc. reactive arthritis
Campylobacter Chicken, meat Moderate: GI symptoms
with bloody diarrhea, GBS
E. coli O157:H7 Ground beef, juices, sprouts, Severe: colon lining and
STEC/EHEC water, etc. kidney damage, HUS, death
Listeria RTE foods, e.g., deli meats, Severe: GI symptoms,
monocytogenes smoked fish, soft cheese, etc. meningitis, death
Clostridium Improperly canned or bottled Severe: paralysis and GI
botulinum food (anaerobic) symptoms, death
WHAT DO WE KNOW ABOUT HAZARDS SUCH AS HOW DOES ESCHERICHIA COLI
O157:H7 CAUSE ILLNESS?
Exposure to
Recovery
E. coli 0157
Infection
Hemolytic
Hemorrhagic
Watery uremic Squeal (not
colitis (bloody
diarrhea syndrome considered)
diarrhea)
5HUS)
Recovery
Death
DEFINING SOME DOSE RESPONSE ISSUES
What are the characteristics of the pathogen/agent
that affect its ability to cause disease in the host
(e.g., infectivity, pathogenicity, virulence)?
What adverse health effects may be associated with
exposure to the pathogen (from mild and self-
limiting symptoms, to life-threatening conditions)?
Who is susceptible to infection
(individual/subpopulation/population)?
SOURCE DATA FOR DOSE RESPONSE ASSESSMENTS
Data input with pros and cons
Outbreak data
Surveillance data
More micro than chemical data relating to illness
Volunteer feeding studies (limited and mostly old data)
Animal studies (uncertainty relating to humans)
In vitro studies
Expert elicitation
DOSE-RESPONSE CURVES FOR MORBIDITY FROM EPIDEMIOLOGICAL
DATA OR EXPERT ELICITATIONS FOR LISTERIA MONOCYTOGENES
1.00E+00
1.00E-02
Buchanan et al.
Lindqvist and Westöö
1.00E-04
Chocolate milk
1.00E-06 Corn
Farber et al.
1.00E-08 Butter
Mexican style cheese
1.00E-10
1.00E-12
1 2 3 4 5 6 7 8 9 10 11 12 13
MICROBIAL RISK ASSESSMENT GENERAL FLOWCHART
Food contamination
Number of bacteria per
gr, raw material
Food processing
Food consumption
Number of bacteria per gr pattern
at retail level
Transport & Describe food
storage handling and amount
and frequency of
Number of bacteria per gr Food
consumption
before consumption handling …
Single exposure
Number of ingested
bacteria for a consumer
Dose-response model
Experimental data
Risk after a single exposure
Risk of infection Dose response
Infection
Risk of illness illness
EXPOSURE ASSESSMENT
Exposure assessment (EA) varies according to the
food product and region
Extent of the EA depends on the risk management
question(s)
Farm-to-Fork (the whole process)
Retail-to-consumption (post production)
Individual food processing/food handling steps
Combines prevalence and concentration of an agent
with consumption amounts and frequency
Pathogen exposure tends to be individual separate
events, whereas chemical tends to be cumulative
over time
EXPOSURE ASSESSMENT
Usually we want frequency and level of an agent
(typically a pathogen) ingested by consumer but
difficult to get data at the final stage of a food
consumed, so we estimate by modeling:
Identify initial and subsequent sources, frequency and
level of contamination
Try and model from various environmental knowns (pH,
aW, time, temperature, etc.) at earlier stages what the
frequency and level of a pathogen will be at
consumption
MATHEMATICAL MODELS
• Models are meant to capture the essential
elements of a process in a simplistic form
• The intention is not to create a perfect and
exact duplicate of reality
• Rather to create a tool that will provide insight
into the system
• Modular approach to describe a complex
system where there are several steps
EXPOSURE ASSESSMENT
SALMONELLA SPP. IN BROILER CHICKEN (FAO/WHO)
GROWTH
RETAIL TRANSPORT STORAGE
STORAGE TO HOME AT HOME
CROSS
COOKING PREPARATION
CONTAMINATION
CONSUMPTION
DOSE
RISK RISK
(CONSUMPTION) (CROSS-CONTAM)
RISK CHARACTERIZATION
• Provides a model that estimates the probability of
illness due to the ingestion of a pathogen in a food with
or without cooking, e.g., Salmonella in chicken or E. coli
O157:H7 in hamburgers
• For most chemicals it is the total exposure not one
food
• Risk measure is the probability of illness
1) by estimating the predicted number of cases per 100,000
population based on contaminated servings eaten
[differences reflect different exposure pathways]
2) the total number of cases in population, e.g., USA,
France, UAE or elsewhere [differences reflect different
population sizes]
CHALLENGES FOR THE RISK ASSESSMENT PROCESS
QUESTIONS ON A SCIENCE-BASED POLICY
Dilemma
• If science based policy is the ideal, why go beyond the experts who
should know best
• However, rarely are polices based purely on science
Fundamental questions:
• Should regulations and policy be based on science or values or a
combination of the two
• Why do some science-based policies not work?
CONSUMER CHOICES
Is there an increase in today’s society allowing consumer
choices, and if so does it increase the risk of spread of
pathogens?
• Almonds can be pasteurized with heat, steam or propylene oxide to
reduce risk of contamination but some groups want to stay with
the raw almonds
• Bagged spinach or lettuce or neither - is irradiation acceptable?
• Raw milk (cheeses) vs. pasteurized milk (cheeses)?
• Steak tartar vs. well cooked ground beef?
• Raw or cooked oysters?
Do we know the risks vs. benefits well enough to
communicate meaningfully with consumers and other
stakeholders?
Danisch and Mudry (2008) reviewed FDA’s Vibrio in oyster risk
assessment and found the analysis too complicated and it left
out values such as liking fresh raw oysters, i.e., partly a
communications issue
IS THE RISK ANALYSIS PARADIGM STILL VALID?
Thus, the classical food risk analysis model (risk
assessment, risk management, and risk communication)
may not be addressing consumers’ concerns on
challenging food safety issues
Perception
• EU consumers appear slightly more concerned about external
risk factors that are beyond their control, e.g., less worried
about personal factors such as food allergies and those linked to
their own behavior, such as food preparation, hygiene and
weight gain
• Women tend to be more worried about food safety than men
• Over 40% of people either ignore stories about food safety or do
nothing despite being worried
So, how does perception affect communication?
SAFE FOOD – EU FUNDED PROJECT
"This Integrated Project addresses the issue of how
consumer confidence in consumer protection and risk
analysis can be restored and strengthened.“
Increased transparency = increased credibility?
Incorporation of societal “values” to create an
integrated framework
SAFE FOODS - A RECENT EU APPROACH TO RISK ANALYSIS
• Framing stage would allow
interested parties, experts
and officials to work
together to gain an initial
shared understanding of the
issue, the objectives of
regulatory action, and
alternative risk management
measures
• Scope is expanded to
include the assessment of
health and environmental
benefits as well as risks,
and the explicit
consideration of economic-
and social-impacts of risk
management action and
their distribution.
• Evaluation stage, interested
parties, experts, and
officials may compare and
weigh the risks, costs, and
benefits and their
distribution.
FRANCIS BACON “THE ADVANCEMENT OF LEARNING”, 1605
• “If a man will begin with certainties he shall end in
doubts, but if he will be content to begin with
doubts, he shall end in certainties.”
• Bacon identified both observation of nature and
formal experimentation as necessary to test a
hypothesis properly
• This concept still holds true today, scientific theories are examined
from a number of different angles and must be reliably repeated
before they become the accepted wisdom to the day
• Risk assessments are estimates and are never the complete truth –
value for making management decisions
QUESTIONS?
