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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.htm

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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.pdf

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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/

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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.htm

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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.html

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Cartoon