People stopped regarding tap water as a luxury a long time ago - in some parts of the world, at least - and for all of us fortunate enough to live in a modern, developed society, tap water is part of our daily lives and we need it as strongly as we need to breathe or sleep. Tap water is cleaned via a process known as "chlorination", during which a series of chemicals are pumped into it to kill germs and dangerous bacteria while still making it fit to be drunk. Although many of us do not particularly enjoy drinking tap water and some even avoid it completely, we often forget that we also wash our hands and shower in it on a daily basis - thus getting regular exposure to the chemicals it contains.

And this may be a problem - especially for pregnant women. Scientists from Birmingham University recently conducted a study on almost 400,000 babies and found a clear connection between chemicals formed during chlorination on the one hand and the occurrence of three severe birth defects, on the other hand. The "guilty" chemicals are called trihalomethanes, or THM for short, and we're all exposed to them daily by drinking, showering or taking baths, swimming in pools or even breathing in steam from a boiling pot of water. THM were found to affect pregnant women more and cause a higher incidence of three birth defects - hole-in-the-heart defect, cleft palate or anencephalus (in which, parts of the baby's brain, skull and scalp are missing).

Doctors say that pregnant women should thus avoid drinking tap water of any kind. As for the other types of exposure, it would, of course, be impractical to stop showering with tap water, so scientists insist on the use of further disinfection methods which limit levels of the chemicals - which, they warn, may harm the unborn baby directly or damage the mother's eggs and thus cause any of the three problems mentioned above. "Water disinfection has an important purpose in reducing microbial load and reducing acute gastro-intestinal infections. Some have claimed it is the best public health measure ever introduced[...]. I don't suggest stopping using tap water but we have to be conscious that at population level some risks may be related to increased levels," warned a member of the research team.