Tests on milk by the Food Safety Authority of Ireland (FSAI) have so far found no traces of a microbe which some scientists believe is linked to the intestinal disorder Crohn's disease.
A British study found that the microbe survived the pasteurisation process, according to the British Food Standards Agency.
The agency said "troubling new questions" had been raised by a study, which found at least one pathogen, mycobacterium paratuberculosis, survived the pasteurisation process and was then cultured from 2.1 per cent of off-the-shelf milk tested.
However, similar tests have been carried out at dairies in the State by the FSAI, and the results have been very good, as the pathogen has not been found in any samples, said Mr Pat O'Mahony, chief specialist of veterinary public health in the FSAI.
These tests have been carried out since September last year, said Mr O'Mahony. Scientists were divided over whether or not there was a link between the pathogen and Crohn's disease, with currently "no definite view on the matter".
Crohn's is an auto-immune disease in which the immune system attacks the lining of the gut, causing severe symptoms which include pain, diarrhoea, fever, loss of appetite and loss of weight.
Tests were performed over an 18-month period on 258 large dairies in England. Scientists were able to culture the pathogen in 10 of 466 samples taken after milk had gone through commercial pasteurisation.
The pasteurisation process involves heating milk to 162 degrees Fahrenheit (72 degrees Celsius) for 15 seconds.
The pathogens often clump together in milk, allowing the pathogens at the centre of the clump to escape the pasteurisation heat, said Mr O'Mahony.
He said, however, that in the light of this new evidence pasteurisation methods had changed, taking place at a higher temperature, or for a longer time, or through a combination of both. These newer methods were designed to kill the bug.