Country
|
Outbreaks
|
Cases
|
Cases/outbreak
|
Annual rate (per 100 000 population)
|
Australia
|
3
|
102
|
34
|
0.060
|
United States
|
9
|
125
|
14
|
0.005
|
Source: Extracted from M&S Food Consultants 2001; after Smith de Waal et al. 2000.
Concentrations in seafood: The results of monitoring for paralytic shellfish poisons in Port Phillip Bay and Western Port Bay in Victoria are shown in Table 4.12 (ANZFA 1999a).
Table 4.12: Paralytic shellfish poison results in mussels in Victoria
Year
|
No. of samples
|
No. of positive samples
|
Average concentration
(all samples)(µg/100 g)
|
Highest concentration
(µg/100g)
|
1987
|
11
|
0
|
0
|
0
|
1988
|
81
|
17
|
29.1
|
480
|
1989
|
88
|
3
|
2
|
66
|
1990
|
87
|
3
|
3.16
|
121
|
1991
|
34
|
5
|
15.4
|
185
|
1992
|
46
|
25
|
710.4
|
10009.6
|
1993
|
160
|
41
|
64.3
|
4127.7
|
1994
|
188
|
25
|
26.6
|
1286.8
|
1995
|
165
|
10
|
6.6
|
406.6
|
1996
|
161
|
0
|
0
|
0
|
1997
|
44
|
0
|
0
|
0
|
Extensive testing for PSP has also taken place in Tasmania in mussels, oysters and scallops. The results are shown in Table 4.13 (ANZFA 1999a).
Table 4.13: Paralytic shellfish poison results in Tasmania
Food
|
No. of samples
|
Average concentration (µg/100 g)
|
Range
|
Mussels
|
168
|
636
|
35–18429
|
Oysters
|
75
|
123
|
38–699
|
Scallops
|
6
|
60
|
56–83
|
Current regulations: A maximum level 0f 0.8 mg/kg for paralytic shellfish poisons (saxitoxin equivalent) has been established in Standard 1.4.1 – Contaminants and Natural Toxicants – of the Code.
Ranking of hazard: PSP is ranked as ‘severe’ in terms of adverse health effects (Section 3, Table 3) because of its potential to be life-threatening or cause chronic sequelae following acute exposure.
Diarrhetic shellfish poisons
Diarrhetic shellfish poisoning is caused by a group of high molecular weight polyethers, including okadaic acid, the dinophysis toxins and the pectenotoxins produced by the armoured dinoflagellate algae Dinophysis fortii and D. acuminata.
In this report, yessotoxins have also been considered as a subset of the diarrhoetic shellfish poisons, although this classification is under review due to apparent significant differences in structure and mode of action between yessotoxins and the ‘true’ DSPs, particularly okadaic acid and dinophysis toxins.
Potentially toxic diarrhoeic shellfish poisoning plankton dinoflagellates in Australian waters include the planktonic species Dinophysis acuminata, D. caudata, D. fortii, D. hastata, D. mitra, D. rotundata, D. tripos and the benthic dinoflagellates Prorocentrum lima, P. elegans, P. hoffmannianum and P. concavum (Morton & Tindall 1995). Dense blooms have occurred in Tasmanian and New Zealand waters, and can sometimes be completely non-toxic, but at other times shellfish can become toxic even when only sparse dinoflagellate populations are present (ANZFA 1999a).
Hazard identification and characterisation: No human fatalities have been reported due to diarrhoeic shellfish poisoning and patients usually recover within three days. Diarrhetic shellfish poisoning is generally a mild gastrointestinal disorder, that is, nausea, vomiting, diarrhoea, and abdominal pain accompanied by chills, headache, and fever. Onset of the disease, depending on the dose of toxin ingested, may be as little as 30 minutes to 2–3 hours, with symptoms of the illness lasting as long as 2–3 days (ANZFA 1999a). Recovery is complete with no after effects and the poisoning is generally not life threatening (FDA 2003). In extreme cases chronic exposure may promote tumour formation in the digestive system (Hallegraeff 2003).
The toxic dose may be as low as 80 µg (Council for Agricultural Science and Technology 1994).
Incidence of human illness: Diarrhoeic shellfish poisoning is usually caused by the consumption of contaminated mussels, oysters and scallops (FDA 2003).
Pipi shellfish poisoning events occurred in New South Wales (56 patients) in December 1997 and in 1998 (20 patients) circumstantially linked to lipid soluble toxins (Hallegraeff 2003).
Concentrations in seafood: Low concentrations of diarrhoeic shellfish poisoning toxins (generally <0.5 mg okadaic acid/gram) have been reported from New Zealand shellfish (Jasperse 1993).
Current regulations: A maximum level of 0.2 mg/kg for diarrhetic shellfish poisons (okadaic acid equivalent) has been established in Standard 1.4.1 – Contaminants and Natural Toxicants – of the Code.
Ranking of hazard: Diarrhoeic shellfish poison is ranked as ‘serious’ in terms of adverse health effects (Section 3, Table 3) because of its potential to cause incapacitating but not life-threatening illness following acute exposure.
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