Drinking Water and Cancer in Louisiana. A Retrospective Mortality Study

Thirteen Louisiana parishes (counties) using the Mississippi river as a source of potable water have the highest mortality rates (1950-1969) in the drinking water source, a comparison of cancer deaths and noncancer deaths from 1960-1975 in selected southern Louisiana parishes was conducted. Parishes were grouped for similarities in industrialization and approximately equal exposure of the population to surface water and ground water. Cancers were studied in groups by hypothesized risk: high for bladder, colon, kidney, liver, lymphoma, rectum, and stomach; low for Hodgkin's lymphoma, leukemia, lung, malignant melanoma, multiple myeloma, and prostate; and questionable for breast, brain, esophagus, and pancreas. Noncancer deaths were randomly selected and matched 1:1 to cancer deaths on age, race, sex, and year and parish group of death. Water source at death was based on residence at death, surface or ground water, and chlorinated or nonchlorinated water. The risk associated with using surface water least likely due solely to change occurred for cancer of the rectum. Other risks which were lower but still greater than 1.0 occurred for cancer of the kidney and breast. No risk was observed for other cancers of the gastrointestinal or urinary tract. Risk for multiple myeloma was associated with use of ground water.