Medical geochemistry of nitrates and human cancer in Sri Lanka.

Abstract

A study of the incidence of various types of human cancer in relation to nitrate concentrations in Sri Lanka revealed a significant positive correlation for stomach, small intestine, oesophagus and liver cancers, as well as total malignant cancer incidence and benign tumours. The Northern and Western Provinces of Sri Lanka showed the highest total cancer rate. The abundance of nitrates in the groundwater of certain provinces of Sri Lanka has been attributed to use of nitrogeneous fertilizers, human and animal wastes in densely populated regions and nitrates produced as result of atmospheric electric discharges and precipitation. Even though the correlation of nitrate abundance and cancer rates is significant, nitrate cannot necessarily be considered as being causative in view of the biological intricacies involved in the complicated mechanism of cancer inducement.