Primary liver cancer and aflatoxin intake in Transkei.

Transkei has an intermediate primary liver cancer (PLC) rate that is unusually high for a corn-based subsistence economy. The situation is complicated by a very high esophageal carcinoma incidence rate and known exposure to hepatocarcinogenic N-nitrosamines. A total of 623 cooked food samples were collected from two northeastern and two southern districts over two seasons, in a single-sample grid pattern, for aflatoxin analysis. Aflatoxin B1 was quantitated in 26% of all samples during 1976, resulting in a mean contamination rate of 0.65 microgram/kg wet food. Mean contamination during 1977 was 0.66 microgram/kg, and 24% of samples were positive. Thus for both years a mean aflatoxin B1 intake of 16.5 ng/kg body weight per day was calculated. When the data were plotted on our published PLC incidence-aflatoxin intake graph constructed with standardized data from four countries, Transkei was well within the 95% confidence limits. Individual district comparisons are handicapped by as yet inadequate PLC incidence data, but rank order correlations (rs) between aflatoxin intakes and the PLC incidence in goldminers originating from the study districts were significant (P less than .05). Corn was the basis of 95% of the meals and was also the main source of contamination. Six of 23 samples of home-brewed corn beer were positive for aflatoxin, resulting in an overall contamination of 0.69 microgram/L.