Pyridine ‘very unlikely’ to have caused mass Teesside crustacean …
Between October and December 2021, huge numbers of crabs and lobsters were reported to have washed up on beaches in Teesside and north Yorkshire, north-east England, displaying twitching and lethargic behaviour, as well as an inability to self-right. [1]
The government had been insisting since the beginning of 2022 that the cause of mortalities was most likely a harmful algal bloom, despite the fact that a previous DEFRA investigation had concluded that “no single, consistent causative factor” had been identified. [2]
However, university research carried out in 2022 went on to cast doubt on the algal bloom theory, and suggested instead that chemical contamination of the seabed by pyridine, as a result of dredging for the new Teesside freeport, could not be ruled out as a cause. [3]
In January this year an expert panel set up by the government concluded that the mass die-offs were unlikely to have been caused by a harmful algal bloom, but even less likely to have been the result of chemical contamination.[4]
At the time of the initial Environment Agency investigation into the cause of the deaths, there was no available validated method to test for pyridine in animal tissues, with experts instead using an adapted version of a method that tests for pyridine in water.
In December 2021, DEFRA commissioned the Centre for Environment, Fisheries and Aquaculture Science (CEFAS), an executive agency of the department, to develop and validate a “robust quantitative method” for pyridine testing.
In a report published today, CEFAS said it had used a “newly validated” method to re-analyse the samples collected during the mass mortality events. The method found that both the sediment and biota samples “returned levels of pyridine within an expected range based upon the predicted low environmental persistence, and high biodegradation rate of the chemical”.[5]
In an analysis of 17 samples, nine of which came from affected areas and had previously been analysed by the Environment Agency, CEFAS found low levels of pyridine in crab tissue and sediments, which it states supports the conclusion of the expert panel that it is “very unlikely” that pyridine caused the crab and lobster mortalities.
The reanalysis of crustacean samples that had originally returned high indicative pyridine levels with the EA method (3-429 mg/kg) demonstrated “very low” concentrations of the chemical (