Answer given by Mr Dimas on behalf of the Commission
20.3.2007
The Commission does not believe that further studies on hydrofluorosilicic acid (H2SiF6) in drinking water should be carried out or that hydrofluorosilicic acid should be banned from Irish drinking water based on the following grounds.
The drinking water guidelines of the World Health Organisation (WHO)[1] do not highlight any toxicological hazards related to the use of fluorosilicic acid in the preparation of drinking water and do not indicate a safety issue.
In drinking water, fluorosilic acid is strongly diluted and, for the resulting fluoride ion (F-), the Drinking Water Directive[2] establishes clear and legally binding standards (1.5 mg F/l), in line with the guideline value of the WHO. Moreover, the Drinking Water Directive states that no substances used in the preparation of drinking water may appear in concentrations higher than necessary for the purpose of their use and may not reduce the protection of human health. The fluoride content indicated for artificial fluoridation of Irish drinking water supplies (0.8 mg F/l) is below the Drinking Water Directive's maximum concentration.
In drinking water preparation, there is a similar situation as regards chlorine. Chlorine, supplied in liquid form, is extremely toxic. When solved and diluted into the water, it disinfects the water and, due to its lower concentration, it is not aggressive for humans and for animals.
Based on the above, the use of fluorosilicic acid in municipal water in Ireland does not seem to present a toxicological threat or an infringement of the Drinking Water Directive. There are, therefore, no plans to undertake a further toxicological review on the use of fluorosilicic acid as a source of fluoride in drinking water.
Below is additional information on hydrofluorsilicic acid in response to the statement of the Honourable Member. Hydrofluorosilicic acid, which is also known as fluorosilicic acid or as sand acid, is the most frequently used substance for public water fluoridation.
The Honourable Member states that the substance is very toxic for humans, animals and aquatic life form. As a matter of fact, the substance is dangerous in a concentrated form. It is highly aggressive not only if swallowed, but also when it gets in contact with eyes or skin or when it is inhaled. It also tends to fume. Therefore it is rated class R34 (causes burns, avoid contact with eyes, skin, …) in the European chemical substances information system.
These properties are of relevance for the handling of this substance, where this substance is normally supplied in concentrations of 20 % to 40 % like in a drinking water plant.
The same properties cannot be seen when hydrofluorosilicic acid is strongly diluted into water, as the fluorosilicic acid decomposes, releasing fluoride ions. In the fluoridation schemes applied in Ireland for the municipal water, hydrofluorosilicic acid is diluted 110 000 times giving rise to desired concentration of fluoride ions
For what concerns the SiF62- remaining in the water, the Scientific Panel on Dietetic Products, Nutrition and Allergies states[3] in its opinion of 22 February 2005, that when consumed by man, readily soluble fluorides ‘such as fluorosilicic [..] are almost completely absorbed [..] after a plasma peak level at 30 minutes’.
- [1] Guidelines for drinking water quality, 2004, ISBN 92 4154638 7.
- [2] Council Directive 98/83/EC of 3 November 1998 on the quality of water intended for human consumption, OJ L 330, 5.12.1998.
- [3] EFSA Journal 2005-192, 1-65 Request EFSA-Q-2003-18.
OJ C 293, 05/12/2007