Longitudinal evaluation of aflatoxin exposure in two cohorts in south-western Uganda

Abstract

Aflatoxins (AF) are a group of mycotoxins. AF exposure causes acute and chronic adverse health effects such as aflatoxicosis and hepatocellular carcinoma in human populations, especially in the developing world. In this study, AF exposure was evaluated using archived serum samples from human immunodeficiency virus (HIV)-seronegative participants from two cohort studies in south-western Uganda. AFB₁–lysine (AFB-Lys) adduct levels were determined via HPLC fluorescence in a total of 713 serum samples from the General Population Cohort (GPC), covering eight time periods between 1989 and 2010. Overall, 90% (642/713) of the samples were positive for AFB-Lys and the median level was 1.58 pg mg⁻¹ albumin (range = 0.40–168 pg mg⁻¹ albumin). AFB-Lys adduct levels were also measured in a total of 374 serum samples from the Rakai Community Cohort Study (RCCS), across four time periods between 1999 and 2003. The averaged detection rate was 92.5% (346/374) and the median level was 1.18 pg mg⁻¹ albumin (range = 0.40–122.5 pg mg⁻¹ albumin). In the GPC study there were no statistically significant differences between demographic parameters, such as age, sex and level of education, and levels of serum AFB-Lys adduct. In the RCCS study, longitudinal analysis using generalised estimating equations revealed significant differences between the adduct levels and residential areas (p = 0.05) and occupations (p = 0.02). This study indicates that AF exposure in people in two populations in south-western Uganda is persistent and has not significantly changed over time. Data from one study, but not the other, indicated that agriculture workers and rural area residents had more AF exposure than those non-agricultural workers and non-rural area residents. These results suggest the need for further study of AF-induced human adverse health effects, especially the predominant diseases in the region.

Keywords:

• aflatoxins
• aflatoxin B₁–lysine adduct
• human exposure
• Uganda
• cohort studies

Acknowledgements

The first three authors contributed equally to the writing of this paper.

Additional information

Funding

This work was partially supported by research contract number ECG-A-00-07-00001-00 from the US Agency for International Development via Peanut CRSP at the University of Georgia; and by planning grant number 1R24TW009489 from the National Institute of Health Fogarty International Center. The authors acknowledge cohort funding from various sources for RCCS and for GPC joint funding by the UK Medical Research Council (MRC) and the UK Department for International Development (DFID) under the MRC/DFID Concordat agreement.