Looking at the flood of water filters available, you have to wonder whether they’re worth the $20 to $1,500 price. For more reasons than taste, your body might think so. Some of these filters can remove compounds from the water that have been associated with bladder cancer.
While the number-one risk factor for bladder cancer is smoking, it’s not the only risk factor for that cancer. Looking at 321 bladder-cancer cases and 261 people with other cancers, researchers saw an association between that cancer and chlorinated drinking water. People who drank such water for more than 30 years (the average was 2 1/2 glasses per day) had nearly twice the risk of that cancer as people who drank water disinfected by other processes. In addition, the more water people drank and the more years they drank it, the higher the risk (American Journal of Epidemiology, October 1993).
Researchers aren’t sure what could be behind the chlorine connection, although they point out that chlorine can react with organic compounds in the water to create substances called trihalomethanes that have been found to be carcinogenic in animals. Sensitive to this issue, municipalities often use a combination of chlorine and ammonia (a process called chloramination) to reduce those potentially harmful by-products. People in the study who drank chloraminated water did not have an increased risk for this cancer.
Now, before you get worried about the water you’ve already been drinking, get the facts: First, bladder cancer is pretty rare – it occurs at a rate of 60 people per 100,000,and many of those cases may be hnked to smoking. Second, find out about your water supply at work and at home by calling someone at your public water system and asking what they use to disinfect the water.
“In many places, levels of trihalomethanes are so low that drinking other types of water isn’t necessary. But other systems have relatively high levels, and it might be worth drinking water from another source or using a filter,” says study leader Michael A. McGeehin, Ph.D., senior epidemiologist at the Agency for Toxic Substances and Disease Registry in Atlanta.
Activated carbon filters are the only type that filter out trihalomethanes. (By the way, they filter chlorine and lead, too.) For a list of filters certified to reduce these compounds, write to NSF (National Sanitation Foundation) International and ask for the information packet on water filters. The address is: P.O. Box 130140-PVN, Ann Arbor, MI 48113-0140 (information not available by phone).
If you’re worried about keeping up the protection when you’re away from home, you might find bottled waters worth the price. All of them are tested for trihalomethanes before they can be put on store shelves.
Reference: Clean Water Act