Shellfish sector smells rat in toxicity tests

New time-consuming rules implemented by the European Union to reduce the risk of shellfish and other seafood poisoning could hit Spain's seafood industry hard, and are of questionable validity, say sector representatives. The common mouse bioassay test, introduced in November, can take up to three days to verify the presence of toxins in shellfish.

A spokesman for the regional government of Galicia, in northwest Spain, where the majority of Europe's seafood is cultivated, say the EU's testing method is too slow, and means that areas from which shells have been harvested must be closed down while the results are awaited.

In response, the regional government says that it is to appeal against the new testing methods. Previously, seafood was tested on rats, which offered almost instant results thus avoiding the need to close the harvest sites for days as a precaution.

Bivalves, and particularly mussels, produced in Galicia's fjords are periodically affected by red tides, a natural event that takes place most years toward the end of summer. In September 2010, 95 percent of Galician mussel raft sites were closed as a result of the presence of biotoxins in phytoplankton. Although there are occasionally severe cases of poisoning, the usual indicator of having eaten affected shellfish is a case of diarrhea.

The European Commission says the new tests are aimed at "the total protection of human health," and that the previous tests on rats were not accurate enough. But Rosa Quintana, the head of the Galician regional government's fisheries department, says that the new tests have not been fully validated, and that "consumers will lose out." The regional government says that the new tests are variable by up to one-third, depending on where they are carried out.

The solution may lie with new early warning technology developed in the United States and Ireland. Chemists at the University of California-San Diego have developed a marker that flags toxin-producing organisms in shellfish by setting up a system to add a fluorescent tag to an enzyme that makes one kind of toxin, okadaic acid. By handing the tag to the molecule that turns the enzyme on, it ensures that only the parts of cells that are capable of making the toxin would glow.

A second test developed at Queen's Institute for Agri-Food and Land Use in Belfast reduces the testing time to monitor harmful toxins in shellfish. The test functions by using unique "detector proteins" to seek out minute amounts of toxins present in mussels, oysters, cockles and scallops.

"The test will not only make shellfish safer to eat, but it will also have a significant impact on global aquaculture industries as they struggle to deal with the rising problems of toxins caused by climate change," said Chris Elliott, a biology professor at Queen's University.