I propose to take Questions Nos. 22 and 115 together. I am aware of the studies referred to by the Deputies. The causes of Alzheimer's Disease have been under investigation for a number of years. One area of investigation involves a possible association between the disease and aluminium in drinking water. However, the recent studies published in Great Britain and Ireland have not established a casual relationship between the two.
Aluminium sulphate has been used worldwide for the past 50 years to clarify water and this method of treatment is the most common source of residual aluminium in water. Aluminium is also one of the commonest metals in the earth's surface and another area of investigation relates to the influence of acid rain in causing the metal to leach from soil into the environment and water.
In the case of Dublin's drinking water, Dublin Corporation monitor levels of residual aluminium on a daily basis, having regard to the quality standard set in the European Communities (Quality of Water Intended for Human Consumption) Regulations, 1988, which gave legal effect to the mandatory limit set by the EC. This limit is difficult to maintain where water treatment works are over-loaded or where filters are in poor condition. In Dublin, the Ballymore Eustace water supply cannot always be kept within the statutory limit for these reasons and slight breaches occur frequently, particularly in winter time.
Last month, however, I approved the acceptance of tenders by Dublin Corporation for major improvement works costing £14 millions at Ballymore Eustace Treatment Works. In addition to providing an extra 40 million gallons of water a day to the Dublin area, this major investment will ensure that the quality standards in the Drinking Water Regulations are consistently met.
In general, Ireland does not experience significant acid deposition, although elevated levels occur from time to time along the eastern seaboard when winds from the east predominate. Irish emissions of the principal primary pollutants involved in the creation of acid deposition, i.e. SO 2 and NO x, are relatively small and do not give rise to significant acidification problems here or elsewhere. Ireland supports moves at international level to deal with the pollutants in question through active participation in the EC Action Programme on the Environment and as a signatory to the 1979 Geneva Convention on Long Range Transboundary Air Pollution which aims to limit and, as far as possible, gradually reduce and prevent air pollution including long range air pollution. At national level, implementation of the Air Pollution Act, 1987, will contribute to the reduction of the emissions in question.
There is no evidence to suggest that acidification is effecting a release of aluminium into waters used for abstraction of drinking water in Ireland. Studies on acidification are being carried out by the Environmental Research Unit, and the issues involved will be kept under close review.