Dioxin levels in milk from cows in the heavily industrialised Cork Harbour area are well below the EU limit in milk, and over the period of testing showed a remarkable decrease.
A study, initiated in 1991 by Cork County Council's veterinary section and taken by the Food Safety Authority of Ireland (FSAI) for analysis in Germany recently, was carried out over that nine-year period, probably the longest for any such study in the State.
"The study concentrated on dairy farms because the dairy cow has been described as the most suitable animal for assessing the effects of industrial effluents on environmental quality and because of the important position which dairy cattle occupy in the human food chain", Mr Jim Buckley, acting chief veterinary officer with Cork County Council, explained.
Since humans are at the high end of the food chain, human tissue can contain relatively high levels of dioxins, which is why foodstuffs of animal origin are of such special importance.
Ten dairy herds, consisting of 900 cows in the immediate harbour area and 300 cows in two herds within a 15-to-20 mile radius, were monitored every year.
The Cork Harbour area, which has a large concentration of chemical industries, has been the focus of concern about environmental contamination, and several other investigations have been undertaken, but nothing of this duration and importance.
The study has found that the dioxins, polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) "are well below the EU limit of three picogramme per gramme of fat for milk and milk products" as specified in new EU regulations, which will come into force from July 1st next.
The study was undertaken because of environmental concerns and unusual incidents of animal ill-health or decreased productivity in the Cork Harbour area and following an explosion and fire in one industrial plant in 1993.
"There was no evidence that exposure to environmental pollutants caused variations in either productivity or the incidence of disease," Mr Buckley said.
"Many incidents which might have been linked with environmental pollution were found to have other causes.
"A broad database of animal disease incidence, productivity and blood composition has been established, and a bank of tissues taken from animals submitted for routine slaughter has been frozen so that they may be analysed for toxins, if required," he said.
The study was made a condition of the air emission licence of one large multinational company locating in the area at the time, and there was scepticism on both the farmers' side and that of the industrialists.
But as Mr Buckley, in a new report explains: "The initial resistance and scepticism of some industrial representatives and farmers have diminished, and confidence in the scheme has grown.
"Animal health surveillance in the vicinity of all industrial sites is clearly neither feasible nor desirable. Nevertheless, when there is heightened public perception of risk from environmental contamination, studies such as this can play an important role in quantifying the risk, in countering allegations where they are ill-founded and in restoring consumer confidence."