Lot's of Water Reduces Bladder Cancer
... But Will the Water Make You Sick?

Dr. Mom's wise advice about drinking plenty of water each day has suddenly taken on new status as a possible way to prevent urinary bladder cancer, the sixth most common form of cancer in the United States.

Generations of kids have grown up hearing that water is essential for good day-to-day health. Those 8 to 10 daily glasses recommended by parents, health teachers, and nutritionists replace fluids lost from the body in sweat, urine, breathing, and feces. Fluids are especially important in people who exercise and lose more water in perspiration. Water also keeps the feces soft and helps prevent constipation.

Water's role in long-term health has just come to light in a study of 48,000 physicians and other health professionals conducted by researchers at Harvard University and Ohio State University. Those who drank six or more cups of water each day had a 51 per cent lower risk of developing bladder cancer than people who drank less than one cup daily.

People who drank milk, fruit juices, soda pop, coffee, tea, and other fluids also reduced their risk of bladder cancer, when compared to individuals with a small total fluid intake. In general, bladder-cancer risk fell 7 per cent for each cup of fluid that people consumed.

Did the source of water - municipal tap water or bottled water - make any difference?

The question is important because past studies hinted that tap water in some parts of the country could increase the risk of bladder cancer. Municipal water-treatment plants use chlorine to purify water. If certain organic chemical pollutants are present in the water, chlorine can combine with them to form harmful by-products.

Harvard's Dr. Dominique S. Michaud, who headed the study, said it was not intended to answer the question directly. But researchers found no ill effect from tap water. Still, an editorial in the New England Journal of Medicine, which published the study, suggested caution about drinking lots of bad-tasting or low-quality municipal or well water.

How on Earth could drinking lots of water prevent bladder cancer? A major theory suggests that carcinogens in urine cause bladder cancer by damaging genetic material in cells in the bladder's inner lining. The bladder is a hollow, elastic organ that stores urine produced by the kidneys until it can be discharged from the body. A typical bladder can hold about two cups of urine.

The carcinogens get into urine from the environment. Cigarette smoke, for instance, is a major source. Cigarette smoking is the major known risk factor for bladder cancer. Both smokers and nonsmokers exposed to environmental tobacco smoke inhale carcinogens through their lungs and into their blood. Some end up in the urine.

Occupation also is a risk factor, according to the American Cancer Society (ACS). The ACS said that workers may be exposed to high-risk chemicals in the rubber, leather, printing, textile, and paint industries in companies that do not follow good workplace safety practices. Some of the high-risk chemicals are no longer used or subject to strict regulations that limit worker exposure to safe levels.

Drinking large amounts of water dilutes the carcinogens. It also reduces the amount of time that they remain in contact with the bladder wall by making people urinate more often.

Increasing water intake is a simple, straightforward lifestyle change for preventing urinary bladder cancer. The new study makes it more important to heed Dr. Mom's advice and drink plenty of water. The ACS estimated that 54,200 new cases of bladder cancer will be diagnosed in the United States in 1999. About 12,100 deaths will occur.

People with high blood pressure or other chronic medical problems may want to chat with the doctor before making any big increases in water intake.