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Abstract
Aflatoxin B1 (AFB1) is a known human carcinogen (Group1), and the mechanism of carcinogenicity has been extensively studied. However, other toxic effects of AFB1, such as immunotoxicity, reproductive and developmental toxicity, have not fully understood. This dissertation presents research involving cohort study populations in rural Uganda and south-central Texas. AFB1 exposure was predominant in rural Ugandan cohorts and higher odds of contracting human immunodeficiency virus (HIV) were observed in highly exposed individuals, which implies that chronic AFB1 exposure at higher levels is associated with HIV acquisition. Additionally, a faster progression from HIV acquisition to the development of acquired immunodeficiency syndrome (AIDS) was observed among the HIV-infected individuals with a hazard ratio of 3.11 per ln (AFB1-lysine). In rural Uganda, the level of AFB1-lysine adduct was significantly associated with abnormal liver enzyme levels, implying that AFB1 exposure is associated with liver disease in the areas. AFB1-lysine adduct in serum was detectable in 84.0 % of the residents of Bexar County, Texas. The geomean of 2.33 in Bexar County, Texas is comparable to the geomean in southwestern Uganda. Consumption of corn-based products and Mexican food items was associated with the higher level of AFB1-lysine adduct in the study participants, Bexar County. An intervention trial with a clay-based enterosorbent (ACCS 100) was carried out to reduce the risk of mycotoxin exposure. A reduction rate of 36% at 1 month after the intervention and 33% at 3 months after the intervention was observed in the low dose (1.5 g/day) treatment group. However, the reduction was not dose-dependent with regards to ACCS ingested. Through these data, we concluded that AFB1 exposure in humans is not only a threat in the developing world but also among the southern U.S. populations; reducing chronic exposure to AFB1 may benefit prevention of potential adverse health effects in these populations.