I propose to take Questions Nos. 16, 56, 64 and 113 together.
Aluminium sulphate is used worldwide in the treatment of drinking water and is accepted by the World Health Organisation and the EC. I am satisfied that its use in accordance with the drinking water regulations is consistent with international practice and is safe. My Department closely follow research developments in this area.
A report of the Quality of Drinking Water in Ireland (1989), compiled by the Environmental Research Unit, was published on 17 October, 1991 and copies are available in the Oireachtas Library. This identifies local authority use of aluminium sulphate in 1989 to treat drinking water, and the incidence of alluminium residuals above the maximum admissible concentration set in the regulations. Some 1,992 samples, covering 456 water supplies, were analysed for aluminium content. Almost 86 per cent of these samples — 1,712 — were in compliance with the requirements of the regulations, while just over 14 per cent — 280 — showed levels in excess of the 0.2 mg per litre standard. The majority of exceedances are not far removed from the maximum admissible concentration. However 2.3 per cent indicate aluminimum concentrations greater than 1.0 mg per litre.
The reports have identified aluminimum as a significant problem. I regard any exceedance of the standard with concern. However, I should emphasise that a casual link has not been established between aluminimum in water and Alzheimer's disease. Counter-measures to deal with the exceedances identified are a priority in the programme of capital works for water supply. Extension and replacement of treatment works and distribution systems, where necessary, are being supported by grants from my Department under that programme. A small number of water supplies are treated with ferric sulphate rather than aluminium sulphate. Further experiments with the use of this alternative coagulant are now underway.
Sanitary authorities have also been asked to review all aspects of the management and operation of water supplies. The indications are that, in many cases, better treatment works practice and more active supervision could bring the drinking water quality into conformity with the regulations.