Occurrence and dietary exposure to organophosphorus esters in foodstuffs of Nigerian origin

Despite extensive evidence of the presence of organophosphate esters (OPEs) in various environmental matrices including foodstuffs in some developed countries, there are no data on the presence of OPEs in African foodstuffs. This study provides the first data on concentrations of OPEs in foods of Nigerian origin by measuring the concentrations of eight OPEs in 85 food items either purchased in Nigeria or from major African stores in Birmingham, UK. Foodstuffs analysed were divided into ten categories. Median concentrations of ∑₈OPEs in melon (Egusi) (17.4 ng/g wet weight (ww)), cassava flour (Fufu) (11.6 ng/g ww), and milk (9.62 ng/g ww) were the highest of the food categories examined. Tris(2-butoxyethyl) phosphate (TBOEP) and triphenyl phosphate (TPHP) were the dominant OPEs. Cassava flour (Fufu) was the major contributor to the estimated daily intakes (EDIs) of Σ₈OPEs, accounting for 26 and 33% of the EDI for children and adults respectively. For individual OPEs, TBOEP contributed the highest median EDI of 183 ng/kg bw/day (42% of the EDI for Σ₈OPEs) for children and 159 ng/kg bw/day (39%) for adults, followed by TPHP (median – children: 92.3 ng/kg bw/day (21%); adults: 90.6 ng/kg bw/day (22%)). The range of OPE concentrations in the present study were comparable to data reported from other countries and EDIs for all OPEs were well below their corresponding health-based reference doses. This study identifies diet as a substantial human exposure pathway to OPEs in Africa.