Chlorine worries keep bubbling up

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HELSINKI--Perhaps nothing has improved our health more than the addition of chlorine to drinking water. That measure alone ended epidemics of typhoid fever, cholera, and other water-borne diseases. But for 20 years now, scientists have worried whether chlorinated water might also cause cancer. A study from Finland offers disturbing clues.

Unlike American cities, those in Finland have long kept detailed records of the compounds added to public water. Finnish government researchers reviewed water records from 56 towns in two years, 1955 and 1970, then examined medical registries for information on local cancer rates in later years.

The results were unsettling. Finns drinking chlorinated surface water were up to 40 percent more likely to have developed kidney cancer than those drinking unchlorinated water, and up to 20 percent more likely to have had cancer of the bladder or stomach.

Those illnesses are exceedingly rare in most of the industrialized world, including the United States, so the increases don't signal a cancer epidemic in the making. But other studies have produced similar findings, and now scientists generally agree that a lifetime of drinking chlorinated water may pose a small risk.

If you have reason to worry-say, because of a family history of bladder cancer--then use unchlorinated bottled water. Alternately, say experts at the National Cancer Institute, you might install a carbon filter on the household spigot from which you drink. You'll want a filter that removes chemicals called trihalomethanes, which are the most common chlorine by-products.

Government agencies are grappling with the issue, and already the Environmental Protection Agency has proposed lowering the amounts of trihalomethanes permitted in public water. But redesigning treatment plants is expensive, so changes will be a long time coming.

PHOTO: Drinking Water

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By John Hastings, Patricia Long, and Michael Mason

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