Post on 30-May-2018
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Quantitative RiskAssessment
Don Schaffner, Ph.D.
Rutgers, The State Universityof NJ
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Overview
- How does risk analysis relate to riskassessment?
- How is risk assessment applied tofood microbiology?
- A very simple example of aquantitative risk assessment
- Web links and more information
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Risk Analysis Components
- (Quantitative) Risk Assessment How big is the risk, what factors control the risk?
Scientific process
- Risk Communication How can we talk about the risk with affected individuals?
Social and psychological process
- Risk Management What can we do about the risk?
Political process
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Cartoon
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Step in Risk Assessment
- Hazard Identification What microbe, food(s) and people are involved?
- Exposure Analysis What is the chance of exposure?
How many cells?
- Dose-Response Analysis
What is the human health effect of the exposure?- Risk Characterization
Complete picture of the assessed risk
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Hazard Identification
- Epidemiological data linking Foods
Pathogens
Human illness
- Special considerations Disease complications
Acute vs. chronic disease Specific sensitive consumer populations
Characteristics of the organism
Organisms mode of action
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Exposure Analysis
- Estimate likelihood of consumption
likely number (dose) of thepathogen
- If quantitative assessment Modeling Simulation
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Exposure - Simple Example
- Initial number of organisms follows aPoisson distribution
- Growth rate is normally distributed
- Product composition and storage
temperature are fixed- The product becomes unsafe when it
contains 100,000 organisms/gram
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Initial number - Poisson
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Growth rate is normal
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Simulation Results
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Dose-Response Analysis
Translates exposure analysisoutput in to a measure of humanhealth
If quantitative
Use dose-response curve Estimate probability of infectionand illness from dose
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Dose response curve
Cassin et al.
Quantitative risk
assessment forEscherichia coli
O157:H7 in
ground beef
hamburgers.
Int.J.Food
Micro.41(1):21-44, 1998.
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Dose-Response factors
- Statistical model(s) to analyze orquantify dose- response relationships
Threshold vs. non-threshold models
- Dose response data Human
Animal
Outbreak or intervention data
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Dose-Response factors
- Source and preparation of challengematerial or inoculum
- Organism type and strain Virulence factors or other measures of
pathogenicity
- Characteristics of the exposedpopulation Age, immune status, etc.
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Risk Characterization
- Final task in risk assessment
- Combines the information from Hazard identification Exposure analysis
Dose-response analysis- Produces a complete picture of
the assessed risk
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A good risk assessment
- Is Transparent
Iterative
- Includes
Variability and uncertainty Management input into problemformulation
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A hot-air balloon floats overhead
RM: Im lost, can you tell me where I am?
RA: Sure, you are 30 feet off the ground
RM: Aha, you must be a risk assessor
RA: Why yes, how did you know?
RM: Because what you told me was technicallycorrect, but of absolutely no use.
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A hot-air balloon floats overhead
RA: Aha, you must be a risk manager?
RM: Why yes, how do you know?
RA: Thats easy, you dont know where youare, what you want or where you are goingand you are in the same position now as you
were before you asked for my help, butnow its my fault!
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Importance of risk assessment
- Teaching Students can see what if...
- Research Pinpointing uncertainties or knowledge gaps
- Industry
Optimizing safety while retaining quality
- Government Designing regulations for the greatest benefit
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For more information
- Annotated bibliography on Food SafetyRisk Assessment, Management and
Communication http://www.nal.usda.gov/fnic/foodborne/risk.htm
- Food Safety Risk Analysis Clearinghouse
http://www.foodriskclearinghouse.umd.edu/welcome.
http://www.nal.usda.gov/fnic/foodborne/risk.htmhttp://www.foodriskclearinghouse.umd.edu/welcome.htmhttp://www.foodriskclearinghouse.umd.edu/welcome.htmhttp://www.nal.usda.gov/fnic/foodborne/risk.htm8/14/2019 QRA - food
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For more information
- Revised Framework for Microbial RiskAssessment ILSI
http://www.ilsi.org/file/mrabook.pdf
- WHO/FAO microbial risk analysispage
http://www.who.int/fsf/mbriskassess/index.h
http://www.ilsi.org/file/mrabook.pdfhttp://www.who.int/fsf/mbriskassess/index.htmhttp://www.who.int/fsf/mbriskassess/index.htmhttp://www.ilsi.org/file/mrabook.pdf8/14/2019 QRA - food
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Software
- USDA Pathogen Modeling
http://www.arserrc.gov
- @risk http://www.palisade.com/
- Crystal ball
http://www.decisioneering.com/
- Analytica
http://www.lumina.com
http://www.arserrc.gov/http://www.palisade.com/http://www.decisioneering.com/http://www.lumina.com/http://www.lumina.com/http://www.decisioneering.com/http://www.palisade.com/http://www.arserrc.gov/8/14/2019 QRA - food
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Books
- T. A. McMeekin, et al.Predictivemicrobiology: Theory and application,Somerset, England:Research Studies Press
Ltd., 1993.- C.H. Haas, et al. Quantitative microbial risk
assessment, Ny, NY: John Wiley & Sons,1999.
- D. Vose. Risk Analysis: A QuantitativeGuide, Chichester:John Wiley & Sons,2000.
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Published risk assessments
- S. enteritidisin eggs http://www.fsis.usda.gov/OPHS/risk/index.htm
- Listeriain RTE foods http://www.foodsafety.gov/~dms/lmrisk.html
- Fluoroquinolone ResistantCampylobacterin Chicken http://www.fda.gov/cvm/antimicrobial/Risk_asses.ht
http://www.fsis.usda.gov/OPHS/risk/index.htmhttp://www.foodsafety.gov/~dms/lmrisk.htmlhttp://www.fda.gov/cvm/antimicrobial/Risk_asses.htmhttp://www.fda.gov/cvm/antimicrobial/Risk_asses.htmhttp://www.foodsafety.gov/~dms/lmrisk.htmlhttp://www.fsis.usda.gov/OPHS/risk/index.htm8/14/2019 QRA - food
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Published risk assessments
- Vibrioin shellfish http://www.cfsan.fda.gov/~dms/vprisk.html
- E.coliO157:H7 in ground beef http://www.fsis.usda.gov/OPHS/ecolrisk/home.htm
- Campylobacterin chicken http://www.who.int/fsf/mbriskassess/studycourse/a
http://www.cfsan.fda.gov/~dms/vprisk.htmlhttp://www.fsis.usda.gov/OPHS/ecolrisk/home.htmhttp://www.who.int/fsf/mbriskassess/studycourse/annac/index.htmlhttp://www.who.int/fsf/mbriskassess/studycourse/annac/index.htmlhttp://www.fsis.usda.gov/OPHS/ecolrisk/home.htmhttp://www.cfsan.fda.gov/~dms/vprisk.html8/14/2019 QRA - food
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Cartoon