Alternative risk ranking methods
Many alternative measures are available for, or have been applied to, the task of ranking the public health and safety risks posed by food, including seafood. Several of these are discussed briefly, below. Further information on these approaches may be obtained by reference to the specific literature cited.
Ross and Sumner’s risk ranger
Risk ranger is a semi-quantitative tool for risk profiling based on deterministic Microsoft Excel spreadsheet functions, designed to help risk managers prioritise hazards for more intensive risk assessment and to inform decisions about the value of investing resources in fully quantitative risk assessments [24,25]. It can also be used to explore the effect of different risk management strategies or the extent of changes needed to bring about a desired reduction in risk.
Users of risk ranger input selections from a prepared list of qualitative statements or provide quantitative data (for example, survey or epidemiological data) to describe the commodity/hazard of interest. Based on these inputs, the tool calculates estimates of the probability and severity of outcomes arising from the level and frequency of exposure. These estimates include:
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probability of illness per day per consumer of interest
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total predicted illnesses per annum in the population of interest
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comparative risk in the population of interest
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a risk ranking.
The risk ranking is a logarithmic scale of risk with outputs ranging from zero (absence of risk) to 100 (certainty of death from each serving of food). Rankings were attributed to broad risk categories of Low: <32; Medium: 32–48; and High: >48.
Ross and Sanderson’s qualitative risk assessment tool
Ross and Sanderson developed a novel tool to rank the potential impact of food-borne disease from various seafood commodity/hazard combinations, as part of their consultancy report for SafeFood NSW [8]. The scheme takes into account three factors: the severity of the illness (including severity of symptoms, illness duration and likelihood of death, and mode of transmission); the probability of illness (including likelihood of exposure and population susceptibility); and the likely effect of processing and cooking on levels of the hazard.
Corlett and Pierson’s hazard classification scheme
Corlett and Pierson developed a two-stage risk assessment tool for food businesses to use in development of HACCP food safety plans [26]. Firstly, the raw materials, ingredients or food, along with the process and the intended consumer, are ranked according to six criteria (Table 1). For every applicable characteristic, the food is assigned a ‘+’. The higher the number of pluses, the greater the degree of risk attending the particular food.
Table 1: Hazard classification of Corlett and Pierson
Hazard
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Risk characteristics
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A
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Special class restricted for at-risk populations, for example, aged, immunocompromised, infants
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B
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Product contains sensitive ingredients
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C
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Process has no step which destroys sensitive organisms
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D
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Product is subject to re-contamination between processing and packaging
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E
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Potential for abuse by distributor or consumer which could render the product hazardous
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F
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Product is consumed without further process to kill micro-organisms
| Risk ranking scheme of Huss et al.
Huss et al. developed a qualitative scheme for categorising risk from consuming different seafoods using six criteria (Table 2) [27]. Specific seafoods are ranked according to the number of the risk characteristics that apply. A food is considered high risk if four or more risk characteristics apply, and low risk if less than four apply.
Table 2: Huss et al. risk ranking scheme
Hazard
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Risk characteristics
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I
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Epidemiological evidence exists to link the product with food-borne disease
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II
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The manufacturing process lacks a Critical Control Point (CCP) for at least one hazard associated with the product
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III
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The product has the potential to become recontaminated after processing
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IV
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There is potential for abusive handling during distribution or in consumer handling
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V
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There is potential for growth of pathogens in the product
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VI
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There is no terminal heat process during meal preparation
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Center for Food Safety and Applied Nutrition/Food Safety and Inspection Service/Center for Disease Control listeria risk assessment
The United States Food and Drug Administration’s Center for Food Safety and Applied Nutrition, in collaboration with the United States Department of Agriculture’s Food Safety and Inspection Service and in consultation with the Department of Health and Human Services’ Centers for Disease Control and Prevention, conducted a qualitative assessment of the relative risk to public health from food-borne L. monocytogenes in selected ready-to-eat foods [11].
The exercise involved individual semi-quantitative risk assessments being performed for each of 23 food categories considered. The results and models for each food category were obtained and then compared, to establish the relative risk among the food categories, including an evaluation of the uncertainty associated with the risk comparison.
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