Why there is no evidence that pyridine killed the English crabs

The North East coast of England experienced a mass mortality event in late 2021 affecting millions of crabs and lobsters. The die-off coincided with the redevelopment of one of the UK's flagship ports, prompting local scientists to suggest the remobilization of dredged industrial contaminants as a cause. A multi-agency investigation found no definitive causal factor; however, re-evaluation of data by consultants drew a different conclusion, linking the industrial compound pyridine to the crustacean deaths. Authors of an unpublished study subsequently claimed that their data demonstrated pyridine to be exceptionally toxic and that their modeling explained the coastal distribution of washups. These data were presented to a cross-party Environmental, Fisheries and Rural Affairs (EFRA) committee in the UK parliament and led to the commissioning of an independent panel to review the data. This panel was also unable to identify a definitive cause, but found that a major role for pyridine was ‘very unlikely’. Unfortunately, the debate has been highly politicised, with misleading information aired by the two leading political parties. Here, several members of that independent review panel refute the pyridine link to the mass mortality, based on both reported data and the known chemistry and behaviour of this molecule, and highlight where the science has been misrepresented by the media.