Carcinogen in a Transkeian Bantu Food Additive

Abstract

THE high incidence of oesophageal cancer in Bantu people in localized areas of the Transkei, between which there is little or none of the disease, has developed rapidly since the early 1940s. This, and the fact that the women spend most of their lives (and men up to the age of 20) within a mile or so of their homes, presents a rare opportunity for studying the aetiology of the disease. A close association was found between the occurrence of the disease in women and signs of molybdenum deficiency in the leaves of their food plants such as pumpkins, beans and maize¹. Molybdenum is essential for nitrogen metabolism in plants and a deficiency is known to lead to an accumulation of nitrate². The addition of nitrate to chopped herbage enhances its tendency to form nitrite and nitrous gases³. These and secondary amines present in all plants might form nitrosamines, many of which are carcinogenic and several of which have been shown to cause oesophageal cancer selectively in rats⁴.