The government is being urged to launch a public health probe into possible links between chlorinated tap water, cancer and problems in pregnancy.

Liberal Democrat consumer affairs spokesman Norman Baker said an in depth programme of research should be set up. 'On something as basic as drinking water, government spending should be a priority.'

Advice to minimise exposure to chlorination by-products (CBP), as long as this does not undermine disinfection, was passed on to water companies from two Department of Health expert committees last July.

The Drinking Water Inspectorate has also told water companies to initiate schemes to improve water treatment to meet tighter EU standards for certain CBPs by 2003 at the latest.

Two studies in California published in 1998 reported a weak-to- moderate association between consumption of tap water and CBPs in tap water and spontaneous abortion.

But the DoH's committee on carcinogenicity of chemicals in food consumer products and the environment said that 'overall' further studies had 'failed to provide persuasive evidence of a consistent relationship between chlorinated drinking water and cancer.'

Public health minister Yvette Cooper told Mr Baker in a recent written parliamentary reply that the small area health statistics unit at London's Imperial College had been funded to examine a link between CBPs and birth problems.

The DoH has commissioned the Medical Research Council institute of environment and health to carry out a£85,000 project to examine epidemiological techniques, including those used to investigate chlorinated drinking water.

Mr Baker, MP for Lewes, said the government might believe that 'the risks resulting from taking chlorine out of tap water would be greater than those caused by keeping it in'. It may be that chlorine eliminates some health hazards, 'but it may also be the case that chlorine is being added to drinking water because it is cheaper than safer alternatives'.