Select Committee on Environment, Food and Rural Affairs Fifth Report


4 Alternative explanations for the atypical results

17. At first, the shellfish industry accepted that the atypical positive DSP results might represent the presence of something that was, or could be, a threat to public health.[26] However, as the period of closures continued, the industry began to doubt the presence of a toxin, as normal episodes of DSP are generally short-lived.[27] Furthermore, they argued that outbreaks of DSP are usually associated with an algal bloom, but that this was not the case in the atypical results.[28]

18. The industry noted that the atypical results began to be found when CEFAS took over monitoring for England and Wales, although DARD began to find some atypical results at around the same time. Moreover, the atypical results appear to have stopped since a common method was introduced at all three laboratories in November. The industry put forward the hypothesis that the results were an artefact of the method used at CEFAS and DARD rather than the presence of a novel toxin.[29]

19. When testing was transferred to CEFAS, the laboratory adopted a different scientific protocol for the MBA to that used at FRS (DARD used a third version of the method). The industry's suggestion is that CEFAS's method resulted in solvents used in the preparation of the shellfish extract remaining in the material that was injected into mice, and that it was these solvents that caused the symptoms and death observed in the atypical results. For example, the CEFAS method involved a more vigorous extraction method, which the industry suggests may increase the likelihood of emulsion formation, which in turn could result in greater volumes of solvent remaining in the final extract.[30]

20. Because none of the laboratories concerned found atypical results in other shellfish as often as in cockles, despite using the same procedure, the industry accepts that some factor associated with cockles was involved too, perhaps the presence of stress-induced compounds, but maintains that there was no evidence of any risk to human health.[31] The industry also criticises other aspects of the way in which the mouse bioassay was carried out, which it believes may have allowed certain cockle compounds to remain the final material and thus contaminate the results.[32]

21. The FSA has investigated the possibility that solvent carry-over from the production of the extract to the material that is injected into the mice is responsible for the atypical symptoms. However no relationship was found between the amount of solvent present in the injected material and atypical results: some samples which contained a lot of solvent did not produce the atypical result and some with little solvent did. FSA says that it is not possible to ensure that solvent is completely removed and therefore have not been able to show that samples that are completely free of solvent may still produce the atypical response. The FSA has also found no link between the type of solvent used and the atypical response. It has concluded that there is no evidence that solvent carry-over explains the atypical response.[33]

22. The atypical results prompted closer scrutiny of the methods used at the three laboratories and an audit was carried out by Professor Hugh Makin. This highlighted the fact that originally the three labs were using three separate versions of the MBA and identified some poor scientific practice, principally a lack of quality assurance. Of particular concern was the fact that there were different approaches to determining whether a particular test result was positive or negative.[34] The FSA and the laboratories concerned have taken steps to address those issues, adopting a common method since November 2003. It is both astonishing and unacceptable that the three laboratories conducting statutory toxin monitoring used different methods, and more importantly, did not appear to have a common standard for determining whether a result was positive or negative.

23. The FSA was slow to recognise that the atypical results merited further investigation, slow to take account of the industry's suggested explanations and was slow to investigate the possibility that the methodology could be at fault. The flaws highlighted in the methods applied by the laboratories, even if they do not explain the atypical results, suggest that the FSA should, at the very least, have paid closer attention to quality control in its investigations. These delays have meant that this crisis has been unduly prolonged.

24. The FSA does not appear to recognise that the extent to which the industry believes that the atypical results can be explained by the solvent and methodology hypothesis. As a result it has not done enough to communicate what it has done to investigate this hypothesis and on what evidence it has rejected it, if indeed it has. In such a delicate situation as this, where the risk of a threat to public health must be balanced against the risk of severe and lasting damage to individuals' livelihoods and to businesses, it is imperative that the Agency take all possible steps to ensure that reasonable hypotheses are rigorously researched and that the outcomes of such research are made clear to the other parties involved.

25. The industry's hypothesis is supported by the fact that the period during which atypical results were found coincided with the period during which a new version of the test was in use. The problem of atypical results lasted from the summer of 2001 to late autumn 2003, and if further atypical results are discovered, it seems unlikely to be resolved unless the cause of the results can be discovered. There is an urgent need for further investigation of the cause of the results and what, if any, are the implications for human health. We understand that the FSA has commissioned research with this aim. We recommend that the FSA pursue its research into the causes of the atypical response with urgency and it should inform us of the outcome of such research. The FSA should inform us of its strategy for responding to any future atypical results should further research prove inconclusive.


26   Ev 12 Back

27   Ev 67 Back

28   Ev 12 Back

29   Ev 1, Ev 12, Ev 67, Ev 86 Back

30   Q3 Back

31   Qq27-28 Back

32   Qq23, 25-26 Back

33   Investigations To Assess Whether Diethyl Ether Or Acetone Carry - Over During The DSP Standard Operating Procedure Is Responsible For The Atypical Response In Mice, FSA Report, 01 October 2003 Back

34   An audit of methods and procedures for lipophilic toxin analysis used by laboratories at CEFAS, FRS and DARD, which undertake the statutory monitoring of shellfish toxins in the UK. Hugh L. J. Makin, 1 October 2003, Section 9, para 5. Back


 
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