Two major etiological agents, hepatitis B virus and
aflatoxin B1, are considered to be involved in the induction of
liver cancer in Africa. In order to elucidate any synergistic effect of these two agents we conducted a study in various parts of Kenya with different
liver cancer incidence in order to establish the rate of exposure to
aflatoxin and the prevalence of
hepatitis infections. Of all tested individuals 12.6% were positive for
aflatoxin exposure as indicated by the urinary excretion of
aflatoxin B1-guanine. Assuming no annual and seasonal variation, a regional variation in the exposure was observed. The highest rate of
aflatoxin exposure was found in the Western Highlands and Central Province. The incidence of
hepatitis infection nationwide as measured by the presence of the
surface antigens was 10.6%, but a wide regional variation was observed. A multiplicative and additive regression analysis to investigate if
hepatitis and
aflatoxin exposure had a synergetic effect in the induction of
liver cancer was negative. However, a moderate degree of correlation between the exposure to
aflatoxin and
liver cancer was observed when the study was limited to certain ethnic groups. The study gives additional support to the hypothesis that
aflatoxin is a human liver
carcinogen.