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Chlorinated water 'increases risk of birth defects'

03/06/2008

Babies born to mothers who drank heavily chlorinated water while pregnant could have an increased risk of a range of birth defects, new research suggests.

Scientists at the University of Birmingham made the link after studying nearly 400,000 babies born in Taiwan.

Their study, published in the journal Environmental Health, found no direct link between the prevalence of any birth defect and the level of chlorination by-product exposure.

But exposure to high levels of chlorination by-products substantially increased the risk of three common defects: ventricular septal defects (holes in the heart), cleft palate and anencephalus (where neural development fails, resulting in the absence of a major portion of the brain, skull and scalp).

Exposure to the highest level of total by-products was associated with a doubled risk of defects.

"The biological mechanism for how these disinfection by-products may cause defects are still unknown," said lead researcher Jouni Jaakkola.

"However, our findings don't just add to the evidence that water chlorination may cause birth defects, but suggest that exposure to chlorination by-products may be responsible for some specific and common defects.

"Whilst the benefits of water chlorination are quite evident, more research needs to be carried out to determine these side-effects."

The UK's Drinking Water Inspectorate (DWI) said however that people need not be worried by the research and pointed to previous studies on the subject.

In 2007 a DWI-funded study with eight times the sample size of the current research found no conclusive link to birth defects.

But DWI principal inspector Sue Pennison added: "We are not complacent and we will look at [the latest] findings and have them reviewed by our scientists and health advisors."