The town of Dundalk on the North-eastern coast of Ireland experiences high levels of stillbirths, miscarriages, birth defects and cancers. Mary Grehan, who has been studying medical abnormalities in Dundalk since the fire at Sellafield (then called Windscale) 40 years ago, found that the disease patterns resembled those experienced around Chernobyl.

More research is needed if the cause, and therefore remedies, can be identified but, for Mary, as a possible source, “Sellafield sticks out like a sore thumb”.

More than 200 kilograms of plutonium were discharged into a bank of sediment in the Irish Sea by the UK's Sellafield nuclear re-processing plant. It appeared that they did not stay there, as scientists predicted, but were washed round the north of Scotland into the North Sea.

Concentrations of plutonium found off the west coast of Denmark had an isotope ratio which pointed the finger at Sellafield. Justin Brown, a senior scientist from the Norwegian Radiation Protection Authority (NRPA) said, "If these sediments (at the bottom of the Irish Sea) are confirmed to be the source, plutonium will be detectable in these waters for the foreseeable future".

Technetium 99 (a radioactive substance with a half life of 215,000 years) has been found in the Irish Sea since the mid-90s. The highest levels are found in lobster and seaweed. Sellafield had been routinely dumping radioactive waste into the sea. Later it was also found in the North Sea and in Norwegian lobsters.

In 2001 British Nuclear Fuels Ltd. (BNFL) admitted that technetium had been found in groundwater both on and off the Sellafield site and accepted that it was the probable cause of the Irish and Norwegian contamination: "Building B241's sludge storage tanks have been suspected of leaking for some years".