Risk assessment provides the scientific basis for risk analysis. It is the process of determining the likelihood that exposure to a hazard, such as a foodborne pathogen, will result in harm or disease; it helps characterize the nature and magnitude of risks. Risk assessments also assist regulators in decision making on food safety guidance and policies by providing a systematic evaluation of the state of knowledge related to the hazard including the degree of uncertainty. The V. parahaemolyticus risk assessment (VPRA) process illustrated in this document adhered to the framework proposed by the CODEX Committee on Food Hygiene (68) and by the National Advisory Committee on Microbiological Criteria for Foods (103), which involves four steps: Hazard Identification, Exposure Assessment, Hazard Characterization/Dose-Response, and Risk Characterization.
This risk assessment utilized quantitative risk assessment modeling, which is a mathematical process used to evaluate the likelihood of adverse human health effects occurring following exposure to a pathogenic microorganism. Or more simply stated, it describes what we know and how certain we are of what we know. The risk is expressed as a mathematical statement of the chance of illness or death after exposure to a specific pathogen and it represents the cumulative probabilities of certain events happening and the uncertainty associated with those events. Quantitative risk assessment modeling is a relatively new approach to the field of microbial risk. The data are represented as large sets of numbers called distributions rather than as point estimates, which offer several potential advantages over traditional approaches. One advantage is that distributions may represent the spread of real world data more accurately than point estimates like a mean. Distributions can also reflect the presence of uncertainty in the data. Another potential advantage is that modeling allows risk assessors to test which factors are most important in determining the magnitude of a risk or what effect control measures will have on a risk. Quantitative models are also flexible; inputs and model components can be changed readily as new data become available.
Determinants of the hazard of V. parahaemolyticus illness due to consumption of oysters containing this pathogen, include: the initial levels of pathogenic V. parahaemolyticus in the oysters at harvest, the effect of normal handling and processing on these levels, and the pathogen's capability to multiply and reach an infectious level in the food prior to consumption. Taking into account these determinants, the risk assessment was divided into three different modules within the CODEX framework: Harvest, Post Harvest, and Public Health Modules. The Public Health Module was further subdivided into three segments: epidemiology, consumption, and dose-response, even though dose-response forms the Hazard Characterization section of the risk assessment.
Hypertext updated by bap/kwg/dms 2001-JAN-30