Dar seafood ppp standard

Food-borne illness associated with Australian seafood

There have been a number of documented outbreaks of seafood-associated food-borne illness in Australia in recent years. Since 1987:

• 
  outbreaks due to finfish have been caused by ciguatoxin, histamine (scombrotoxin) and wax esters (gempylotoxin)
  
• 
  outbreaks due to crustacea have been caused by bacterial and viral pathogens, including Salmonella Typhi, S. Typhimurium PT 64, Vibrio parahaemolyticus, V. cholerae non-O1/ non-O139, hepatitis A virus and Clostridium perfringens
  
• 
  outbreaks due to molluscs have been caused by Noroviruses, hepatitis A virus, V. parahaemolyticus, V. vulnificus, S. Mississippi, Listeria monocytogenes and diarrhoetic shellfish poison (Appendix 2; [19]).
  
  
  

However, these outbreak data represent only a small component of the total morbidity due to seafood consumption in Australia. Sporadic cases of food-borne illness are not included in these datasets (unless a death results), and a low level of reporting of food-borne illness is generally understood to be a major problem. While physicians are required to report some specific illnesses with food-borne aetiology, many food-borne illnesses are not notifiable. Furthermore, most people do not seek medical attention for various mild forms of gastroenteritis, and even quite severe illnesses are typically significantly under-reported [20].
In 2003, OzFoodNet conservatively estimated that the number of cases of food-borne illness in Australia in a typical year from all food sources is between 4 million and 6.9 million cases (mid point 5.4 million cases) [21]. However, in the same report, data is given for outbreaks of food-borne illness in Australia in 2002, indicating there were 92 documented outbreaks affecting only 1819 people. The extent of under-reporting of food-borne illness evident in these datasets highlights the danger of relying solely on outbreak data in evaluating the public health risks due to food safety hazards.

Approaches taken in this report

Grouping of seafood commodities

The extent to which a food safety hazard is likely to be present in seafood and to give rise to a public health and safety risk depends on a number of factors. These factors are related to the biology of the particular seafood species, its growing environment, and the specific activities along its production and processing supply chain. To simplify consideration of these factors, this report considers separately the broad classes of seafood species (bivalve and cephalopod molluscs, crustacea and finfish), and subsequently considers hazards associated with specific commodity groups within these classes. For molluscs and crustacea, these groups are defined broadly in terms of species, genus or family (for example, bivalves, abalone, prawns), whereas for finfish, the groups are based on the different post-harvest processing steps undertaken (for example, canning, smoking, fermenting).

In cases where these relatively broad commodity classes mask a wide range of relative risk across species or between different geographical areas, the impact of these factors on the rankings are discussed more fully in the summary and conclusions. Examples include methylmercury in larger, predatory and long-lived fish species and viral and algal toxin contamination of oysters and other bivalves harvested from polluted and/or unmanaged waters.

Format of this report

The method by which relative risk rankings were estimated for each commodity group is explained in Section 3. This section describes how consideration of the severity of adverse health effects due to hazards present in food and estimates of the likelihood of those adverse health effects occurring in the Australian population due to consumption of seafood are combined into commodity/hazard relative risk rankings. The method by which these rankings are used to provide the overall relative risk ranking for each commodity group is explained.

The relative risk rankings for individual seafood commodity groups are contained in Section 4. The likelihood and severity of adverse health affects due to the hazards potentially associated with each seafood commodity are described, and the estimated risk rankings tabulated. An overall ranking for the commodity is then generated by consideration of the highest relative risk level pertaining to that commodity. Those commodities ranked as relatively high or medium risk are discussed further in Section 5, with attendant uncertainties described in Section 6. The overall conclusions are in Section 7.
In order to avoid unnecessary duplication of material and to simplify this report, various sets of relevant data have also been collated in separate appendixes.
Appendix 1 contains information relevant to the through-chain assessment of hazards in seafood commodities. It includes:

• 
  a description of the production and processing supply chain for each sector/commodity
  
• 
  a discussion of the points along that supply chain at which specific hazards might be introduced, increased, reduced or eliminated
  
• 
  a description of the effects of processing and handling and the impacts of existing food safety regulations and voluntary risk management practices on levels of hazards.
  

This information is important in assessing the level of food safety risk in cases where epidemiological and hazard prevalence data are scarce, and as an aid to developing appropriate risk management strategies.

Australian epidemiological data on outbreaks of food-borne illness linked to consumption of seafood between January 1995 and June 2002 are at Appendix 2.
Information on the consumption by (non-infant) Australians of various classes of seafood is at Appendix 3.
Detailed notes on the properties of identified food-borne hazards and their association with seafood commodities relevant to this evaluation are provided at Appendix 4.
The information includes data, where available, on the prevalence and concentration of hazards in seafood and further discussion of epidemiological evidence of food-borne illness due to the presence of each hazard in seafood in Australia or overseas. Much of the information in Appendix 4 has been drawn from formal quantitative and qualitative assessments of the risks associated with consumption of various classes of seafood, or with exposure to certain hazards within the total diet.

Risk ranking method

The public health and safety risks posed by particular seafood sectors have been ranked in general agreement with the principles for risk characterisation as outlined by the Codex Alimentarius Commission.

Codex defines risk as:

a function of the probability of an adverse health effect and the severity of that effect, consequential to a hazard(s) in food [22]

and recommends that a risk characterisation should provide a:

qualitative and/or quantitative estimation, including attendant uncertainties, of the probability of occurrence and severity of known or potential adverse health effects in a given population based on hazard identification, hazard characterization and exposure assessment [22].

In the case of microbiological hazards, Codex further suggests that such estimates may be validated by comparison with relevant epidemiological data [23]. However, it should be recognised that epidemiological data do not clearly reflect the ‘severity’ component of risk, except to the extent that the severity of illness impacts upon the relative level of reporting.