Shellfish toxin testing
The recently published Annual report (2009) of the Animals Scientific Procedures Inspectorate and Division highlights progress towards suitable alternatives to replace the use of mice in the testing for toxins in shellfish.
There are a number of different types of toxins that can contaminate shellfish if they feed on certain toxic phytoplankton (algae). These include groups of shellfish poisons (SPs) known as paralytic (PSP), lipophilic (previously known as diarrhetic) (DSP), neurotoxic (NSP), and amnesic (ASP) toxins. If contaminated shellfish are eaten, the symptoms can include diarrhoea and abdominal cramps, numbness and tingling of lips and fingers, and, in extreme cases, death. ASP, PSP and DSP toxins can be present in UK waters. European food hygiene regulations have traditionally required testing for PSP and DSP to use live mouse tests (bioassays).
The Inspectorate has been working with the Food Standards Agency (which has funded a large amount of work on developing alternative methods) and the UK testing laboratories to find validated replacements for these mouse tests. A chemical method has been developed that is effective in detecting PSP in mussels, the shellfish species that is most frequently tested. This new method has therefore replaced mice in the majority of tests for PSP toxins, thus significantly reducing the number of animals that are used. Work is continuing to see whether this method can be adapted to detect PSP in other types of shellfish.In the meantime, a pre-screening method is being used that detects samples that might be toxic, thereby reducing the number of samples that need to be tested on a live animal. Over 80 per cent fewer mice are now used to test shellfish samples for PSP than would have been needed for the same number of samples five years ago.
The search for a reliable replacement test for DSP toxins is also looking promising. The Home Office hopes that a new method might be fully validated for the major species of shellfish during the next year. This should also lead to a further significant reduction in animal use.
In addition to these ongoing attempts to replace the animal bioassays, other strategies are being pursued to reduce the number of animals used per sample, and to refine the ongoing animal tests. These include the use of humane endpoints in the DSP test. This means that, wherever replacing the bioassays is not currently possible, the number of animals used has been reduced and the tests are shorter and more humane, so reducing animal suffering.
The ongoing collaboration between the Home Office, Food Standards Agency and the UK testing laboratory (an executive agency of DEFRA) clearly indicates the Government's real commitment to the 3Rs. UK regulators will also continue to press for early acceptance by the relevant European Authorities of replacements for these animal tests. The alternative methods being developed give more robust results than the mouse bioassays and so the new measures should reduce suffering both in people and in mice.