Report No DWI0090



Jun 1984


This contract relates to investigations of the trace inorganic constituents in tap-water, undertaken between April 1981 and March 1984. The project had two objectives:

To investigate the relationship between the chemical composition of drinking water, the prevalence of CVD risk factors measured in man and the incidence or cardiovascular disease.

To develop a reliable, practicable and economical method of assessing the mean intake of metals derived from plumbing systems by typical inhabitants of a particular house or water supply zone. This objective embraces several metals, but particular emphasis has been given to lead.

This report is concerned solely with progress under the first of these objectives. Work on the second objective will continue beyond March 1984, for one year to end in March 1985, and so it is being covered by separate reports.

The contract period has seen the publication of a number of epidemiological papers based mainly on information generated by the earlier stage of the contract. New information has, however, been presented on the relationship between blood-lead and water-lead.

Collaboration with the Royal Free Hospital has continued. WRC has provided the water data for Phase II of the Regional Heart Study, and offered interpretive advice on it to the research team at the Royal Free Hospital. An initial examination of this data on a town-by-town basis suggests that, even allowing for personal risk factors such as smoking and blood pressure, water quality still "explains" some of the regional variation in cardiovascular disease. The initiative for further statistical analysis rests mainly with the team from the Royal Free Hospital.

The practical implications of research to date have been widely publicised, as have the results of the "changes" work.

The overall outcome of the epidemiological research assisted by this contract has been to confirm the existence of a water-related factor, independent of socio-economic or geographical influences on CVD. Estimates of the strength of this factor have, however, been smaller than suggested by some of the earlier studies. It has not been possible to identify a specific water constituent as responsible, and there is little hope of doing so by epidemiological research.

While there remains further scope for epidemiological work to demonstrate whether the water factor, that appears to operate at the community level, is actually effective in terms of risk to the individual, the initiation of new studies of the type needed for this is probably not possible for WRC. Work by the Royal Free Hospital on Phases II and III of the Regional Heart Study is however not yet complete and will be continuing.

Copies of this report may be available as an Acrobat pdf download under the 'Find Completed Research' heading on the DWI website.