THE level of radioactive contamination from Sellafield is now so low that it should not put people off eating fish from the Irish Sea, according to the Radiological Protection Institute of Ireland.
In a new report on radioactivity levels in the Irish marine environment, the RPII said the total estimated radiation dose to a heavy consumer of seafood, attributable to discharges from Sellafield, fell from 70 microsieverts per year in the early 1980s to just two microsieverts last year.
Putting this in perspective, the report notes that the estimated annual dose to seafood eaters from a naturally occurring radionuclide, polonium 210 - present in fish throughout the world - is 148 microsieverts, "clearly dwarfing the dose now incurred due to Sellafield discharges".
By comparison, the annual average dose to a person in Ireland from all natural and artificial sources of radioactivity is estimated at 3,000 microsieverts. In previous reports, the RPII said radon gas represents a much higher risk than BNFL's nuclear reprocessing operations.
However, it said particular note had to be taken of the presence in the Irish Sea of highly toxic plutonium and americium, due to discharges from Sellafield. Though these were known to be in "small quantities", they would remain present in the marine environment for centuries.
According to the report, a "sharp increase" in the levels of technetium 99 was detected in seaweed collected along the east coast in August, 1994, indicating the first effects of the commissioning of the THORP plant at Sellafield. However, technetium's radiotoxicity is relatively low.
The report also notes that it makes "only a minor contribution" to the radiation dose from Sellafield. The principal contributor to this dose is caesium 137, and the most common way of ingesting it is through consumption of fish or shellfish caught in the Irish Sea.
"The long term and continuing radioactive contamination of the Irish Sea due to activities at Sellafield is highly objectionable from an Irish viewpoint, and the RPII recognises the widespread anxiety of people in Ireland about risks to health arising from this contamination," said one of the report's authors.
But Mr John Cunningham, RPII assistant chief executive, added that its job was to determine whether this anxiety was justified by scientific evidence. "Our latest findings show that the level of contamination is so low that it should not deter people from eating fish caught in the Irish Sea."
He stressed the RPII continued to consider that Sellafield's most serious threat to Ireland was the risk of a major accident.
