Dar seafood ppp standard

4. Discussion of relative risk rankings

The relative risk rankings for those commodity/hazard pairings ranked as medium or high are summarised in Table 12. The factors impacting upon the rankings are discussed below, and a comparison is made with the findings of other relevant risk assessments or ranking exercises.

High relative risk rankings

Oysters and other bivalve molluscs – polluted and/or unmonitored waters

Oysters and other bivalve molluscs (except when the consumed product is only the adductor muscle, for example, roe-off scallops) harvested from growing environments likely to be exposed to faecal contamination and/or not under a shellfish safety management scheme were found to present a relatively high risk to public health. The risk is mainly due to the likelihood of illness caused by contamination with the hepatitis A virus and algal biotoxins (particularly amnesic shellfish poison and paralytic shellfish poison). These hazards are introduced in the pre-harvest phase of bivalve production.

The incidence of food-borne illness from eating oysters and other bivalve molluscs in Australia is characterised by a number of small outbreaks and sporadic cases due to Vibrio species and a few large outbreaks due to enteric viruses in oysters harvested from polluted and inadequately controlled waters. While adoption of risk management strategies has improved the safety of bivalve shellfish in Australia, residual risks remain. Monitoring of harvest waters for indicators of sewage pollution (for example, faecal or total coliforms) helps manage the risks from enteric pathogens, bacterial and viral, but cannot predict levels of Vibrio species in oysters. Monitoring for potentially toxic species of algae only partly reduces the risks due to algal biotoxins, as concentrations of toxin in oysters do not necessarily always correlate with levels of algae in the water.
Based on these considerations, for oysters and bivalves harvested from waters managed by a comprehensive shellfish safety scheme, such as the ASQAP, the relative risk ranking reduces to medium.

The risk ranking for cooked oysters and other bivalves is the same as the ranking for product to be eaten raw, as the hazards leading to the risk ranking are not greatly affected by the light cooking normally applied to these products.

Table 12: Summary of selected seafood commodities including current risk management*

Commodity	Hazard/environment or species	Severity	Likelihood	Relative risk ranking^1	Current risk management
Raw oysters	V. vulnificus	Serious	Likely	Medium	ASQAP/Ch 3^2
	V. cholerae O1/O139	Severe	Unlikely	Medium	ASQAP/Ch 3^2
	Noroviruses/Uncontrolled^3	Moderate	Very likely	Medium
	Noroviruses/Managed^4	Moderate	Unlikely	Low	ASQAP
	Hepatitis A virus/ Uncontrolled^3	Serious	Very likely	High
	Hepatitis A virus/Managed^4	Serious	Unlikely	Low	ASQAP
	Algal biotoxins/Uncontrolled^3	Severe	Likely	High	Ch 1
	Algal biotoxins/Managed^4	Severe	Unlikely	Medium	ASQAP/Ch 1
	Arsenic, Cadmium, Lead	Severe	Unlikely	Medium	ASQAP/Ch 1
Commodity	Hazard/environment or species	Severity	Likelihood	Relative risk ranking^1	Current risk management
Cooked oysters	V. cholerae O1	Severe	Unlikely	Medium	ASQAP/Ch 3^2
	Noroviruses/Uncontrolled^3	Moderate	Very likely	Medium	Ch 3^2
	Noroviruses Managed^4	Moderate	Unlikely	Low	ASQAP/Ch 3^2
	Hepatitis A virus/ Uncontrolled^3	Serious	Very likely	High
	Hepatitis A virus/Managed^4	Serious	Unlikely	Low	ASQAP
	Algal biotoxins//Uncontrolled^3	Severe	Likely	High	Ch 1
	Algal biotoxins/Managed^4	Severe	Unlikely	Medium	ASQAP/Ch 1
	Arsenic, Cadmium, Lead	Severe	Unlikely	Medium	ASQAP/Ch 1
Cooked abalone /roe-off scallops	Algal biotoxins	Severe	Unlikely	Medium	Ch 1
Green prawns	V. cholerae O1^5	Severe	Unlikely	Medium	Ch 3^2
	Salmonella Typhi^5	Severe	Unlikely	Medium	Ch 1/Ch 3^2
	Arsenic	Severe	Unlikely	Medium	Ch 1
Cooked prawns	V. cholerae O1^5	Severe	Unlikely	Medium	Ch 3^2
	Salmonella Typhi^5	Severe	Unlikely	Medium	Ch1/Ch 3^2
	Arsenic	Severe	Unlikely	Medium	Ch 1
Chilled/ frozen whole fin fish and fillets	Mercury, Ciguatoxin^6	Serious	Unlikely	Low	Ch 1/Advisory Notes
	Ciguatoxin/Tropical^7	Serious	Likely	Medium	Advisory Notes
	Mercury/Predatory species^8	Serious	Likely	Medium	Ch 1/Advisory Notes
	Arsenic	Severe	Unlikely	Medium	Ch 1
Canned fish products	C. botulinum^4, 9	Severe	Unlikely	Medium	GMP/GHP
	Arsenic	Severe	Unlikely	Medium	Ch 1
Cold-smoked fish products	C. botulinum^4, 9	Severe	Unlikely	Medium	GMP/GHP
	L. monocytogenes	Serious	Unlikely	Low^10	Ch 1/Ch 3^2/Advisory
	L. monocytogenes	Severe	Likely	High^10, 12	Ch 1/Ch 3^2/Advisory
	L. monocytogenes	Serious	Likely	Medium^11
	L. monocytogenes	Severe	Very likely	High^11, 12
Hot-smoked fish products	C. botulinum^4, 9	Severe	Unlikely	Medium	GMP/GHP

* Relative risk rankings are under constant review to identify emerging significant information.
1. Risk ranking reflects current practice for that commodity/seafood sector. The risk ranking is based on the severity of the hazard and an estimate of the likelihood of illness that takes into account various factors, including current risk management practices.
2. Chapter 3 provisions in the Code apply to the processing sector only.
3. ‘Uncontrolled’ describes a growing environment not under a shellfish safety management scheme and/or likely to be exposed to faecal contamination. Includes growing waters adjacent to urban areas and rural habitation. In contrast, a growing environment considered pristine is unlikely to be exposed to faecal contamination. Pristine environments would typically include growing waters remote from human habitation and even if uncontrolled, present similar risk to managed waters for enteric pathogens. Algal toxins remain a risk for pristine environments.
4. Where a food safety hazard is controlled under a management system/program, the likelihood of illness is very low.
5. For product from intensive farming systems or estuarine harvest areas subject to human faecal contamination.
6. Majority of finfish present a low risk to consumers (serious x unlikely) due to mercury or ciguatoxin.
7. Ciguatoxin may be found in larger specimens of particular species of tropical and sub-tropical finfish from certain fishing areas. It is predominantly a problem in the recreational fishing sector (Table 4.19).
8. Predatory species – mercury is a problem in large, long-living or predatory fish, such as swordfish, shark/flake and some tuna. These fish tend to accumulate higher levels of methylmercury than other species. The relative risk ranking is medium for the at-risk sub-population (the foetus) when the mother consumes mainly large, predatory or long-lived fish species.
9. Industry adherence to good manufacturing practice, good hygiene practice and appropriate product formulation (for example, pH, levels of salt, preservatives) control this hazard.
10. When correctly managed, the risk ranking is low for the general population (serious x unlikely), but high for at-risk sub populations.
11. When not managed, that is, processing, product handling and storage not adequately controlled, the risk ranking is medium for the general population and high for at-risk populations.
12. L. monocytogenes is a severe hazard for at risk populations.
Key: ASQAP = Australian Shellfish Quality Assurance Program; GMP = good manufacturing practices; GHP = good hygiene practices.

Findings of other risk assessments

This high relative risk ranking for oysters and other bivalves from polluted and/or unmanaged waters is consistent with the findings of other risk assessments and ranking exercises conducted in Australia on viruses and algal biotoxins in molluscs.

The National Risk Validation Project ranked producers, harvesters, processors and vendors of raw ready-to-eat seafood (including oysters and other bivalves) amongst the five highest risk food industry sectors for food-borne illness in Australia, based on recent epidemiological data [19].
Ross and Sanderson [8] found that consumption of raw shellfish carried a relatively high risk of viral infection compared to other seafoods, whilst recognising that the generally low level of reported illness suggested existing control strategies are effective. They also deduced that the risk of illness due to algal toxins was reduced from medium to low when shellfish were harvested under a quality assurance system. These findings are consistent with the estimates of the likelihood of adverse health effects derived in this report (Table 12).
Sumner [9] ranked the risks from viruses in shellfish from contaminated waters and from algal toxins from uncontrolled waters in an algal event as high (risk rankings of 67 and 72, respectively), with the rankings dropping to low (risk rankings of 31) when harvesting was from approved waters under a quality assurance management system. Again, these are broadly in line with the risk ranking derived in this report (noting that a ranking of 32 is considered ‘medium risk’ in the Sumner system).

ANZFA [4] concluded that the available data suggested the potential for significant health risk from consumption of shellfish contaminated with algal biotoxins. As a result of that analysis, new end-point maximum level standards were introduced for diarrhoetic and neurotoxic shellfish poisons in bivalve molluscs, and standards were maintained unchanged for amnesic and paralytic shellfish poisons in bivalve molluscs in the Code.

Cold-smoked ready-to-eat finfish

Ready-to-eat cold-smoked finfish (and other ready-to-eat cold-smoked seafood products) present a higher risk to public health relative to other seafoods due to the possibility of contamination with Listeria monocytogenes and the potentially severe illness it causes in at-risk population sub-groups such as pregnant women. L. monocytogenes is a ubiquitous organism often found in processing environments, and may also be present in fish at the time of harvest. Cold smoking is not a listericidal process.

Recognition of the risks by both regulators and the industry has resulted in a high level of management of L. monocytogenes in Australia and a lower risk of illness to the general population. FSANZ has previously recognised the inherent risk to the general population due to L. monocytogenes in cold-smoked seafoods by including a microbiological limit standard for the organism in ‘ready-to-eat processed finfish, other than fully retorted finfish’ in the Code. When the food safety risks are managed, such that cold-smoked seafoods meet this regulatory requirement, the relative risk ranking for the general population is low, although the relative risk ranking for susceptible populations (for example, pregnant women, neonates and the elderly) is high. FSANZ is currently reviewing its dietary advice to these at-risk sub-groups in order to manage their food safety risks due to L. monocytogenes from all food sources.
If the food safety risks are not properly managed, such that cold-smoked seafoods do not meet the microbiological limit standard for L. monocytogenes, the relative risk ranking is high for at-risk sub-groups and medium for the general population. This takes account of the relatively long shelf life of the product, the high standards of hygiene and sanitation in processing, and good temperature controls across the food supply chain, up to and including the consumer, that is needed to ensure the safety of the product.
Invasive listeriosis is mainly confined to susceptible sub-populations, such as pregnant woman and their unborn children, neonates, immunocompromised people and the elderly. In addition, there is general susceptibility to a milder gastrointestinal illness due to L. monocytogenes.
While cold-smoked seafoods have been linked to outbreaks of listeriosis overseas, there has been no such epidemiological linkage established in Australia. However, there are several factors that might lead to an underestimation of the linkage. Listeriosis is primarily a sporadic disease mainly affecting the susceptible sub-populations and, although it can infect healthy people, the low rate of infection in the general population probably means some outbreaks go undetected [58].

In addition, there are inherent difficulties in determining the food vehicle due to the potentially long incubation time (up to three months) of listeriosis.

Findings of other risk assessments

Several recent risk assessments and ranking exercises have considered the public health and safety risk of L. monocytogenes in cold-smoked seafoods. There are some apparent inconsistencies between the findings of these studies.

Ross and Sanderson qualitatively ranked the risk to New South Wales consumers of listeriosis from consumption of ready-to-eat smoked seafood products to be low, relative to other seafood/hazard combinations. However, application of their quantitative ranking tool led to a higher relative ranking, behind only viruses and algal biotoxins in molluscs, and C. botulinum in vacuum-packed seafoods [8]. This higher ranking reflects the greater influence of the severity of outcomes in the ranking tool compared to the qualitative risk ranking. They further estimated that the incidence of listeriosis in the susceptible sub-population in New South Wales would be, at most, a few cases per annum, depending on the degree of adherence to the microbiological limit standard in the Code.
Sumner ranked the public health risk from smoked seafood containing L. monocytogenes as medium (risk ranking 39 for the general population, 47 for the foetus – the extremely susceptible sub-population).
However, he concluded that the estimate of 14 cases per annum due to smoked seafood, as generated by the ranking tool, was not supported by the epidemiological data, and that several factors could account for a lower actual case rate [9]. The average annual reported incidence of listeriosis in Australia (from all food sources) in the period 1991–2002 (inclusive) was 59 cases [56].
The quantitative comparative risk ranking of L. monocytogenes in ready-to-eat foods conducted jointly in the United States by the Food and Drug Administration, United States Department of Agriculture and Centers for Disease Control and Prevention concluded that smoked seafoods had a relatively high risk ranking on a per-serving basis, but only a moderate relative risk ranking on a per-annum basis (estimated 1.3 cases per annum in the whole population) [11]. However, these rankings are for ‘likelihood of illness’ (specifically, invasive Listeriosis) in the total population, and do not take into account a severity factor because the comparisons were made between risks due to a single hazard (L. monocytogenes) in a large number of foods. The report also generated estimates of likelihood of illness in the perinatal and elderly susceptible populations.
FSANZ previously concluded that L. monocytogenes in ready-to-eat finfish (such as cold-smoked salmon) poses a significant public health risk, particularly for vulnerable subgroups, recognising that while the incidence of disease is low in the population, the impact (death) for the infected individual is severe [49]. The assessment led to maintenance of the microbiological limit standard for L. monocytogenes in smoked seafood.