Water Chlorination, Mutagenicity, and Cancer Epidemiology.

This article comments on the epidemiological investigation of the correlation between chlorination and the incidence of cancer. As soon as this investigation began, it encountered three hurdles, including the determination which organs might be affected. There has been a general convergence of findings in that cancers of the bladder, colon, and rectum have been associated with various measures of chlorination by-product contamination. An especially challenging aspect of studying environmental contamination and disease is to define and then estimate exposure at the relevant time in a person's life.