Radioactive discharge from Cumbria's Sellafield reprocessing plant continues to be the dominant source of contamination of the Irish Sea, a report says.
The Sellafield complex is the main source of pollution in the Irish Sea
The study, by Ireland's nuclear watchdog, also found, however, that the level of radioactivity from waste was lower than that seen in previous decades.
It reassured consumers that eating fish and shellfish caught in the area did not pose a significant risk.
But Irish politicians expressed concern at the news that Sellafield remained the main source of contamination.
The Irish Green Party's Ciaran Cuffe said the British Government should find an alternative way to deal with waste from the site.
He said that discharging it straight into the Irish Sea was a "19th Century solution to a modern day problem".
The report is further evidence that reprocessing is a dirty business.
Irish government spokesman
Emmet Stagg, Irish Labour's spokesman on nuclear safety, said the report by the Radiological Protection Institute of Ireland reinforced his view that the plant should be closed down.
He said: "The debate over Sellafield has gone on far too long.
"We know it is a risk, we know the dangers it poses and we know all about the pollution it spreads into the atmosphere and the sea."
A spokesman for Irish environment minister Martin Cullen said the government would still be calling on the Britain to close the Sellafield reprocessing plant down.
He added: "The report is further evidence - if it was needed - that reprocessing is a dirty business."
A spokeswoman for BNFL said she welcomed the fact that there had been a continuing reduction in the amount of discharge from Sellafield.
She said: "Even though this was the highest source of contamination of the Irish Sea the amount is still negligible.
She added that much of the reaction to reports of this kind was "highly misinformed".
The RPII report was produced after analysing about 300 fish, shellfish, seaweed and water samples from the Irish Sea.