Nitrates also are a by-product of municipal waste treatment. And while some have found an association with such diseases as non-Hodgkin's lymphoma, there has only been one study done, in Spain, published in 1993, that showed an association between nitrate, a municipal water supply and an increased risk for bladder cancer.
Bladder cancer is the sixth most common cancer in the United States.
The American Cancer Society predicted about 53,200 new cases of bladder cancer in 2001 in this country. About 12,200 Americans died of the disease, which is more common among men than women, although no one knows why. Weyer and his colleagues used data from more than 41,000 women, aged 55 or older, in the Iowa Women's Health Study. We were looking at the women in the cohort who were using the same water supply for more than 10 years. That turned out to be about 22,000 women, of whom, about 16,500 were using the municipal water supplies from about 400 municipalities.