Can tap water cause bladder cancer?
issues surrounding tap water or municipal drinking water have been looked at in a number of population-based surveys. Some have been better controlled than others, and there is conflicting data. There is data to suggest two sources of carcinogens or potential problems within the drinking water. One is chlorinated water - chlorine metabolites have been associated, depending on the amount of chlorine in the water, to suggest that there may be a very slight increase in the hazard ratio, or the risk of developing lifetime bladder cancer. The other has involved nitrite content within the water, though the data is conflicting. The data from Iowa that suggested that the nitrate levels in water increased a woman's risk of developing bladder cancer, but at the same time showed that it reduced the risk of uterine cancer, cervical cancer, and colorectal cancer. It's a little bit unclear. The chlorine data also showed that there was an increased associated risk of brain cancer with higher chlorine levels, although that's never been substantiated. Right now, there is certainly no clear cut evidence to suggest that we should stop drinking tap water. In fact, there is evidence that water consumption itself is protective. As in the case of a bladder infection where you want to flush out the bacteria, you want to flush out the carcinogens if there are any in the bladder, and by maintaining good hydration, frequent urination, large volume urination, it has been shown to decrease the risk of bladder cancer. The good news today is we've got lots of choices, and there's a lot of waters. In terms of suggesting that tap water is not safe to drink, we don't have the data right now to back that up.
