mouse bioassay

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The Mouse Bioassay for Diarrhetic Shellfish Poisoning: A Gross Misuse of Laboratory Animals and of Scientific Methodology

Robert D. Combes

The UK shellfish industry has recently been affected by the statutory closure of several cockle beds, following the detection of samples causing rapid and severe reactions in the regulatory approved test for diarrhetic shellfish poisoning (DSP) toxins, the mouse bioassay (MBA). It is contended that these socalled atypical results are due to procedural artefacts of the MBA; so far, several studies have failed to identify their cause. This paper critically assesses the development, regulatory use and methodological deficiencies of the MBA. It also discusses how testing for DSP toxins could and should have been improved and made more humane by applying the Three Rs concept of Reduction, Refinement and Replacement, and by the proper validation of the test method used. It is concluded that the MBA should not have been developed for the routine screening of shellfish samples, as it has a substantially severe endpoint and is not used as part of a tiered-testing strategy with non-animal methods. Moreover, during the UK monitoring programme for DSP toxins, the assay has been used without an optimised and universal protocol, and apparently without due regard to the principles of basic scientific methodology. In view of this, the atypical results obtained for cockle samples cannot be relied on as evidence of a human health hazard. It is recommended that the use of the MBA should be discontinued as soon as possible, in favour of other methods, especially those involving non-animal techniques. In the short-term, these methods should be based on analytical chemical detection systems and the essential availability of the relevant pure toxin standards. The lack of any known toxins in samples should be taken as evidence of lack of contamination. The suitability of the existing non-animal methods needs to be assessed as a matter of urgency. It is crucial that all new methods should be properly validated, and that their acceptability for their stated purposes should be endorsed by recognised criteria and validation centres, before being recommended to, or required by, regulatory agencies. In this way, the possibility that scientifically unsuitable methods will once again be used for monitoring for the contamination of shellfish with toxins can be avoided. This gross misuse of laboratory animals and ill-judged application of science should never be allowed to occur again.
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Implementing Scientifically-robust and Humane Shellfish Toxicity Testing: We’re Still Waiting

Gemma Buckland

The response to a Parliamentary Question put to the then-Home Office Minister on 8 March 2006, was that “All protocols for the detection of toxins in shellfish intended for human consumption were assigned a substantial severity limit”, and that “A total of 6,468 animals were used in the relevant procedures [for the testing of shellfish toxins in the UK] during 2004”. The official European Union (EU) method for shellfish toxin testing is the Mouse Bioassay (MBA). The MBA is the primary method, although the Rat Bioassay (RBA) is permitted for some toxins. Six years later, following the completion of ten reports from the European Food Safety Authority (EFSA) stating that current reliance on the MBA is scientifically inappropriate, the regulatory climate for testing is almost unchanged, despite the availability of alternatives. The reliance on such a scientifically questionable method, and the welfare concerns for the animals used, highlight the extent of the clash between policy and science. The ongoing struggle to persuade the European Commission to formally adopt non-animal testing methods for all of the relevant toxins has been fruitless, and evidence remains that thousands of mice are used every year in lethal tests that could be replaced. There is an absolute requirement for advanced scientific methods to replace questionable methods which rely on outdated, inaccurate animal tests; in this case, marine biotoxin testing has surely been waiting in line for far too long.
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