Aflatoxin Exposure from Milk in Rural Kenya and the Contribution to the Risk of Liver Cancer

Milk is an important commodity in Kenya; the country has the largest dairy herd and highest per capita milk consumption in East Africa. As such, hazards in milk are of concern. Aflatoxin M-1 (AFM(1)) is a toxic metabolite of aflatoxin B-1 (AFB(1)) excreted in milk by lactating animals after ingesting AFB(1)-contaminated feeds. This metabolite is injurious to human health, but there is little information on the risk to human health posed by AFM(1) in milk in rural Kenya. To fill this gap, a quantitative risk assessment (QRA) applying probabilistic statistical tools to quantify risks was conducted. This assessed the risk of liver cancer posed by AFM(1) in milk, assuming 10-fold lower carcinogenicity than AFB(1). Data from four agro-ecological zones in Kenya (semi-arid, temperate, sub-humid and humid) were used. We estimated that people were exposed to between 0.3 and 1 ng AFM(1) per kg body weight per day through the consumption of milk. The annual incidence rates of cancer attributed to the consumption of AFM(1) in milk were 3.5 x 10(-3) (95% CI: 3 x 10(-3)-3.9 x 10(-3)), 2.9 x 10(-3) (95% CI: 2.5 x 10(-3)-3.3 x 10(-3)), 1.4 x 10(-3) (95% CI: 1.2 x 10(-3)-1.5 x 10(-3)) and 2.7 x 10(-3) (95% CI: 2.3 x 10(-3)-3 x 10(-3)) cancers per 100,000 in adult females, adult males, children 6-18 years old, and in children less than five years old, respectively. Our results show that aflatoxin exposure from milk contributes relatively little to the incidence of liver cancer. Nonetheless, risk managers should take action based on cumulative exposure from all sources of aflatoxins.