2.8.1 Worldwide regulations
Several countries have already established or proposed
regulations for PSP. Most regulations are set for PSP toxins as a group. In
general, limits have often been set at 400 MU/100 g or
80 µg STX eq/100
g. Some countries indicate specific regulations for one of the PSP toxins,
mostly STX. In most cases, existing regulations refer to shellfish. However,
some countries mention molluscs generally or bivalves specifically as the types
of products for which the maximum permissible levels of PSP toxins are
set.
Many countries still use the standard mouse bioassay of the AOAC International as the method of analysis for official purposes. A directive came into force in the European Union in January 1993 stating that the total PSP content in molluscs has to be determined according to the “biological testing method in association, if necessary, with a chemical method for detection of STX. If the results are challenged, the reference method shall be the biological method”.
Different concentration units are used to express the tolerance level: mouse units/g (MU/g) and mg/g (incidentally mg/ml). The latter unit seems to be less appropriate in the countries that use the mouse bioassay because they actually test for toxicity in the mouse. Expression of a tolerance level for PSP in µg/g would be valuable if the various PSP toxins exhibit the same toxicity, which is not the case. If the unit µg/g still would be preferred above MU/g, one might consider application of a toxic equivalence factor and expression of the concentration of the various PSP toxins (if these can be selectively measured) in concentration units of STX (Mons et al., 1998).
2.8.2 Europe
European Union
In EU Directive 91/492/EEC, a limit for PSP toxins in bivalve molluscs is laid down at 80 mg STX eq/100 g of meat. The official method of analysis is the (mouse) bioassay, if needed in association with a chemical detection method. If the results are challenged, the reference method is the bioassay (EC, 1991a).
Results of studies with Acanthocardia tuberculatum
(Mediterranean cockle) led the European Commission to permit heating as a
means to partially detoxify A. tuberculatum. It was allowed to harvest
Acanthocardia tuberculatum when PSP levels in the edible parts
exceed
80 µg STX eq/100 g tissue but are less than 300 µg STX
eq/100 g. If analysis of the heated product has shown that STX levels are below
the EU legal limit of 80 µg/100 g, this product may be marketed and sold
for human consumption (EC, 1996). Most European countries also have monitoring
programmes to check for PSP producing organisms.
2.8.3 Africa
Morocco
The limit for STX in molluscs is 80 µg STX eq/100 g. The method of analysis is the mouse bioassay (Fernández, 1998)
2.8.4 North America
Canada
Molluscs should contain less than 80 mg STX eq/100 g. The mouse bioassay is the required
method of analysis. Products (soft shell clams and mussels) with levels
between
80 and 160 mg STX eq/100 g may be
canned (Shumway et al., 1995). Butter clams containing 300 to 500 µg
STX eq/100g may be marketed after removing the entire siphon. Butter clams
containing 80 to 300 µg STX eq/100 g may be marketed after removing the
distal half of the siphon (Fernández, 1998).
In the western Bay of Fundy, eastern Canada, phytoplankton samples have been collected since 1988 at four stations. Alexandrium blooms occur annually from late May to August with the highest concentrations occurring from 9 to 21 July most years. Future plans include further refining and quality control, and exploring the temporal and spatial variability in the patterns more fully (Martin et al., 2001). A monitoring programme for a.o. Alexandrium spp. exists. Fishery product harvesting areas are closed when toxin levels in shellfish exceed tolerable limits (Hallegraeff et al., 1995).
The United States of America
The limit for PSP toxins in bivalves is set at 80 mg STX eq/100 g. The method of analysis is the mouse bioassay (Shumway et al., 1995). Shellfish with PSP levels over 80 µg STX eq/100 g tissue destined for canning or subjected to evisceration may be harvested (Fernández, 2000).
2.8.5 Central and South America
Argentina
The limit for STX in molluscs is 400 MU/ 100 g. The method of analysis is the mouse bioassay. Snails to be canned may contain up to 160 µg STX eq/100 g (Fernández, 1998). Argentina has a national monitoring programme for mussel toxicity in each coastal province involving regional laboratories and one fixed station in Mar del Plata (Ferrari, 2001).
Brazil
Brazil has implemented a pilot monitoring initiative for one year but does not have a national monitoring programme (Ferrari, 2001).
Chile
The limit for STX in molluscs is 80 µg STX eq/100 g. The method of analysis is the mouse bioassay (Fernández, 1998). Up until 2001, PSP and DSP toxins have had a severe public health and economic impact in Chile. Consequently, all natural fish beds from 44 °SL southwards were closed and nationwide monitoring programmes maintained (Suárez-Isla, 2001).
Guatemala
The limit for STX in molluscs is 80 µg STX eq/100 g. The method of analysis is the mouse bioassay (Fernández, 1998).
Mexico
In Mexico, a regulatory limit of 30 µg STX eq/100 g is valid. The method of analysis is the mouse bioassay (Aune, 2001).
Panama
The limit for PSP toxins in bivalves is 400 MU/100 g in Panama. The method of analysis is the mouse bioassay (Shumway et al., 1995).
Uruguay
The limit for STX in molluscs is 400 MU/100 g in Uruguay. The method of analysis is the mouse bioassay (Fernández, 1998). Uruguay has a national monitoring programme on mussel toxicity and toxic phytoplankton (Ferrari, 2001).
Venezuela
The limit for STX in molluscs is 80 µg STX eq/100 g. The method of analysis is the mouse bioassay (Fernández, 1998)
2.8.6 Asia
China, Hong Kong Special Administrative Region
The limit for PSP toxins in shellfish is 400 MU/100 g. The method of analysis is the mouse bioassay (Shumway et al., 1995).
Japan
The limit for PSP toxins in bivalves is 400 MU/100 g. The method of analysis is the mouse bioassay (Shumway et al., 1995).
Malaysia
Up until 1990, problems related to PSP incidents were relatively simple, being confined to the west coast of Sabah in Borneo. An effective shellfish toxicity monitoring programme was established by the Malaysian Department of Fisheries, which greatly reduced the occurrences of PSP despite recurring algal blooms. A PSP incident in 1991 on the Malaysian peninsula, linked to the consumption of mussels from Sebatu in the Straits of Malacca, prompted the government to establish an additional shellfish toxicity monitoring facility based at the Fisheries Research Institute in Penang. In September 2001, PSP cases following the consumption of clams from the east coast of the Peninsula Malaysia were reported. Logistical considerations warrant the establishment of a shellfish toxicity monitoring facility on the east coast of Peninsula Malaysia (Usup and Ahmad, 2001).
The Philippines
In the Philippines, a tolerance limit of 40 µg STX eq/100 g is valid (Aune, 2001).
Singapore
The limit for STX in bivalves is 80 mg/100 g. The method of analysis is the mouse bioassay (Shumway et al., 1995).
The Republic of Korea
The limit for gonyautoxins in bivalves is 400 MU/100 g. The method of analysis is the mouse bioassay and the LC method (Shumway et al., 1995).
2.8.7 Oceania
Australia
The limit in shellfish is 80 mg STX eq/100 g of shellfish meat. The method of analysis is the mouse bioassay (Shumway et al., 1995).
New Zealand
The New Zealand Biotoxin Monitoring Programme combines regular shellfish testing and phytoplankton monitoring. The regulatory limit in shellfish is 80 µg STX eq/100 g of shellfish meat (Sim and Wilson, 1997). Shellfish testing currently involves mouse bioassay screen testing with confirmatory testing (Busby and Seamer, 2001).
A new Biotoxin Monitoring Programme providing data that is highly accurate, in a shorter time and without the use of mouse bioassay’s, is being developed. This new programme will implement test methods based on LC-MS providing chemical analytical data in place of bioassay screen test results. The development and implementation of new test methods are in discussion including funding, method validation, testing regulations, availability of analytical standards, comparison to existing tests, type of instrumentation and international cooperation (McNabb and Holland, 2001).
