英语医药学专业.doc

Introduction to quantitative risk assessment Risk analysis is a valuable tool in the management of microbial food safety issues and can provide a systematic approach for the regulatory authorities and the food industry to control the risk posed by a pathogen in a particular food commodity. Risk analysis consists of three elements: risk assessment, risk management and risk communication. Risk assessment is the scientific part of the process in which the hazards are identified and the risk posed by that particular hazard (i.e. pathogen) is calculated. The principles of risk assessment including the four stages involved (hazard identification, exposure assessment, hazard characterisation and risk characterisation) are outlined by the Codex Alimentarius Commission (Codex, 1999). Each of the stages is summarised below. 1.1. Hazard identification A hazard is defined as an agent having an adverse effect on the public health of the human population and may pose a short term, chronic, or fatal risk to a person. The identification of microbial hazard associated with a particular food is generally based on information generated from routine microbial analysis of the commodity or from an epidemiological linkage of a particular pathogen with a case of food borne infection. 1.2. Exposure assessment Exposure assessment is a quantitative estimation of the presence of a contaminant in a serving of food at the time of consumption, or as close to this stage as is scientifically possible and practical. However, the final estimation of the numbers and prevalence of a pathogen in the food is of ten based on an accumulation of data on the prevalence and numbers of pathogen at key points in the food chain with data included on how particular stages in the food chain affect the numbers/prevalence of the pathogen. The final step in the process estimates the amount of contaminant in a single serving, with information on the typical amount of food consumed in a serving procured