Doctors are reviewing medical records of more than 370 patients who received blood products which may not have been properly prepared.
The products were specifically manufactured at the Cork centre of the Irish Blood Transfusion Service (IBTS) for babies and cancer patients in the Munster region.
The IBTS confirmed last night that a review was under way into patients who received the irradiated blood products between August 2003 and April 2004.
The IBTS said "all relevant hospitals and clinicians" had been contacted and of 377 patients reviewed to date no adverse reactions had been found.
Two separate irradiation problems were discovered at the Cork centre of the blood bank during an internal IBTS review in April this year and in a separate inspection by the Irish Medicines Board (IMB) last December. In April it was found that blood products were "marginally under-irradiated" and in December they were found to be "marginally over-irradiated".
An IBTS spokeswoman said doctors ordered irradiated blood products for patients who had severe impairment of the immune system. These include premature babies and babies who get in-utero transfusions, as well as patients with some types of cancer, including lymphomas and leukaemias. Blood products not properly irradiated can lead to a reaction in some patients which is fatal.
The IBTS said in a statement to The Irish Times that the medical charts of patients who received the blood products either had been, or were still being, checked.
"Ninety-six per cent of the relevant medical charts have now been reviewed and no adverse events relating to the transfusion of irradiated blood occurred in any of those patients," it said. It was a matter for doctors to notify the patients themselves.
The IBTS said it viewed these irradiation issues "with the utmost seriousness" and has responded accordingly. "Our central concern as an organisation is patient safety and the board notes that there has been no detected negative impact on those who were administered these products. We have worked with and will continue to work with the IMB to ensure that such incidents will not recur."
Asked if any action had been taken against any member of staff at the Cork centre over the incidents, the IBTS said it has a policy of not responding to any questions concerning individual staff members.
It is understood a further IMB inspection in July found no further problems with irradiation at the Cork centre. The problems discovered earlier arose because of the way an irradiation machine was calibrated.