Due to the high magnitude of the results and the wide geographical spread of the affected beds, the FSA instigated a multi-agency investigation to try to determine a potential cause. A full evaluation of the investigation reports has been carried out by the FSA and other key regulatory partners to assess the findings.
No conclusive cause for the event has been identified. However, a number of possible causes have been ruled out and recommendations from the reports are also being considered.
The FSA is holding a stakeholder event at the end of January 2016 to review findings from the reports with the shellfish industry and other agencies.
The FSA is responsible for classifying shellfish harvesting areas. Its official control monitoring uses E.coli as an indicator to determine the level of faecal contamination in an area.
Between 9 and 16 July 2015, a high proportion of samples of raw shellfish, 40 out of 67 samples, taken from beds along the South West and South coast generated exceptionally high results. All of the samples had been tested at the same official control laboratory, with results between three to six orders of magnitude greater than the levels which might be expected.
Immediate action was taken to temporarily close the affected areas. This action was in line with standard procedures to prevent potentially contaminated shellfish being placed on the market.
Following an assessment of the situation, the FSA made the prompt decision to deviate from the strict protocol and allow beds to reopen following one compliant sample, rather than the usual two. This decision was taken as other water testing carried out by the Environment Agency (EA) did not show elevated levels of faecal indicator bacteria in water. In addition, the unprecedented nature of the results and the lack of a clear cause, including rainfall or sewage discharge-related data, suggested there was no immediate risk to consumers.
As an additional precaution, the industry were asked to implement enhanced testing on each batch of shellfish harvested, until a second investigative resample of the harvesting area showed a return to E.coli levels within the usual safety limits.
The FSA has confirmed the results under investigation will be omitted from the annual classification carried out in August so will not affect shellfish beds that were closed at the time of the incident.
The FSA investigation comprised four main elements:
- Audit by the National Reference laboratory (NRL) of the official controls laboratory which had tested all the samples for which the exceptionally high results were reported. This included a review of the findings of the laboratory’s own investigation.
- Statistical analysis by the Centre for Environment, Fisheries and Aquaculture Science (Cefas) to establish whether the E.coli test results fell within an acceptable range for the areas affected.
- An EA review of bathing water results, rainfall data and waste water discharge statistics.
- An independent expert opinion on the likelihood of such a magnitude of E.coli results over such a large area, how quickly the results could return to normal levels and the types of situation that could cause such widespread high levels of E.coli contamination.