Quantitative Risk Assessment Don Schaffner, Ph.D. Rutgers, The State University of NJ Food Safety Microbiology - February, 2005

Food Safety Microbiology - February, 2005 Overview How does risk analysis relate to risk assessment? How is risk assessment applied to food microbiology? A very simple example of a quantitative risk assessment Web links and more information Food Safety Microbiology - February, 2005

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 Food Safety Microbiology - February, 2005

Food Safety Microbiology - February, 2005 Cartoon Food Safety Microbiology - February, 2005

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 Food Safety Microbiology - February, 2005

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 Food Safety Microbiology - February, 2005

Food Safety Microbiology - February, 2005 Exposure Analysis Estimate likelihood of consumption likely number (dose) of the pathogen If “quantitative” assessment Modeling Simulation Food Safety Microbiology - February, 2005

Exposure - Simple Example Initial number of organisms follows a Poisson distribution Growth rate is normally distributed Product composition and storage temperature are fixed The product becomes unsafe when it contains 100,000 organisms/gram Food Safety Microbiology - February, 2005

Initial number - Poisson Food Safety Microbiology - February, 2005

Food Safety Microbiology - February, 2005 Growth rate is normal Food Safety Microbiology - February, 2005

Food Safety Microbiology - February, 2005 Simulation Results Food Safety Microbiology - February, 2005

Dose-Response Analysis Translates exposure analysis output in to a measure of human health If “quantitative” Use dose-response curve Estimate probability of infection and illness from dose Food Safety Microbiology - February, 2005

Food Safety Microbiology - February, 2005 Dose response curve Cassin et al. Quantitative risk assessment for Escherichia coli O157:H7 in ground beef hamburgers. Int.J.Food Micro. 41 (1):21-44, 1998. Food Safety Microbiology - February, 2005

Dose-Response factors Statistical model(s) to analyze or quantify dose- response relationships Threshold vs. non-threshold models Dose response data Human Animal Outbreak or intervention data Food Safety Microbiology - February, 2005

Dose-Response factors Source and preparation of challenge material or inoculum Organism type and strain Virulence factors or other measures of pathogenicity Characteristics of the exposed population Age, immune status, etc. Food Safety Microbiology - February, 2005

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 Food Safety Microbiology - February, 2005

A good risk assessment… Transparent Iterative Includes… Variability and uncertainty Management input into problem formulation Food Safety Microbiology - February, 2005

A hot-air balloon floats overhead… RM: I’m 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 technically correct, but of absolutely no use. Food Safety Microbiology - February, 2005

A hot-air balloon floats overhead… RA: Aha, you must be a risk manager? RM: Why yes, how do you know? RA: That’s easy, you don’t know where you are, what you want or where you are going… and you are in the same position now as you were before you asked for my help, but now it’s my fault! Food Safety Microbiology - February, 2005

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 Food Safety Microbiology - February, 2005

Food Safety Microbiology - February, 2005 For more information Annotated bibliography on Food Safety Risk Assessment, Management and Communication http://www.nal.usda.gov/fnic/foodborne/risk.htm Food Safety Risk Analysis Clearinghouse http://www.foodriskclearinghouse.umd.edu/welcome.htm Food Safety Microbiology - February, 2005

Food Safety Microbiology - February, 2005 For more information Revised Framework for Microbial Risk Assessment – ILSI http://www.ilsi.org/file/mrabook.pdf WHO/FAO microbial risk analysis page http://www.who.int/fsf/mbriskassess/index.htm Food Safety Microbiology - February, 2005

Food Safety Microbiology - February, 2005 Software USDA Pathogen Modeling http://www.arserrc.gov @risk http://www.palisade.com/ Crystal ball http://www.decisioneering.com/ Analytica http://www.lumina.com Food Safety Microbiology - February, 2005

Food Safety Microbiology - February, 2005 Books T. A. McMeekin, et al. Predictive microbiology: 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 Quantitative Guide, Chichester:John Wiley & Sons, 2000. Food Safety Microbiology - February, 2005

Published risk assessments S. enteritidis in eggs http://www.fsis.usda.gov/OPHS/risk/index.htm Listeria in RTE foods http://www.foodsafety.gov/~dms/lmrisk.html Fluoroquinolone Resistant Campylobacter in Chicken http://www.fda.gov/cvm/antimicrobial/Risk_asses.htm Food Safety Microbiology - February, 2005

Published risk assessments Vibrio in shellfish http://www.cfsan.fda.gov/~dms/vprisk.html E.coli O157:H7 in ground beef http://www.fsis.usda.gov/OPHS/ecolrisk/home.htm Campylobacter in chicken http://www.who.int/fsf/mbriskassess/studycourse/annac/index.html Food Safety Microbiology - February, 2005

Food Safety Microbiology - February, 2005 Cartoon Food Safety Microbiology - February, 2005