6 February 2003
QUALITY OF TAP WATER AFFECTED BY CERTAIN TYPES OF HOUSEHOLD APPLIANCES, SAYS DWI RESEARCH
The standard of tap water in this country has been increasing year by year for the last decade. In 2001, 99.86 per cent of 2.8 million samples taken by water companies met the required standards. But research recently commissioned by the Drinking Water Inspectorate (DWI) shows that the high quality of tap water supplied by water companies in England and Wales could be affected by contact with some household equipment, including certain types of kettle.
The research has shown that there is a high pick-up of nickel if water is boiled in certain types of electric kettle. The research also showed that jug filters increased the acidity of water and that boiling the filtered water might release even higher concentrations of nickel. .
The standard for nickel in tap water is currently 50 microgrammes per litre. (See below : effects of nickel exposure). Researchers found that boiling water in kettles with exposed elements not made of stainless steel increased the average concentration of nickel to about 1000 microgrammes per litre. European proposals for standardisation of water supply fittings are expected to lead to the withdrawal of nickel coatings in direct contact with tap water. This will not, however, cover consumer appliances such as kettles.
Effects of Nickel Exposure
John Fawell, international toxicologist says
“ Nickel is an important metal that occurs widely in the environment and is found naturally in food and drinking water. It is known to be toxic at high intakes but toxicity in humans, other than those exposed in particular industrial circumstances, is very unusual. The World Health Organization considered nickel in their drinking water guidelines and developed a guideline value of 0.02 mg/litre based on effects in laboratory animals. This guideline is currently being considered for revision in the light of new studies, which will probably result in a modest increase in the guideline value. The United States Environmental Protection Agency has established a lifetime drinking water health advisory level of 0.1 mg/l based on the same studies as those used to develop WHO guidelines. The no effect levels in these studies are well below the levels to which humans are normally exposed. Nickel is well known to cause skin sensitisation and a high proportion of the population, particularly women, have become allergic to nickel, mostly through nickel costume jewellery, such as ear-rings, in extended contact with the skin. Ingestion of nickel at high levels in food or drinking water has been shown to cause dermatitis in some, but not all, nickel sensitive individuals. These effects are not normally severe and there is evidence that ingestion of low doses of nickel may even desensitise some individuals who are nickel allergic. Exposure by ingestion does not cause sensitisation, this only occurs following extended skin contact with the metal.”
The Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT) has been asked for its view on the significance of the findings for public health. The COT concluded, “In order to assess the risks associated with nickel in boiled water, more information is needed on the possible exposure resulting from use of different types of filter and kettle under normal conditions of use.” The full COT statement has been posted on the Food Standards Agency’s website along with Background papers.
Further studies are now being commissioned to provide more information on exposure to nickel. These will compare different water sources and will provide more data on consumer exposure to nickel from boiled water.
Answers to Questions you may have and how this might affect you
The full report of the DWI research and Details of how to obtain a copy can be viewed at www.fwr.org under FWR Publications and Summaries which can be found by clicking "Website Contents".
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Published 6 February 2003
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