Human Health Risk Assessment of Pesticide Residues in Some Cereals Sold in Nigerian Markets

Abstract

The occurrence of pesticide residues in agricultural produce and processed foodstuffs can be detrimental to global efforts aimed at ensuring food security. This study evaluated the presence of some pesticide residues in rice and oats sold in Nigerian markets. Samples collected were homogenized, extracted with a hexane-acetone mixture and analyzed using the gas chromatography coupled with mass spectrometry (GC-MS) technique. Results of the analysis showed that the concentrations of lindane isomers in rice and oats ranged from 0.00 mg.kg^-1 to 0.13 mg.kg^-1. Heptachlor concentrations in rice and oats ranged between 0.02 mg.kg^-1 and 0.18 mg.kg^-1 whereas the concentration ranges of endosulphan and endrin aldehyde were 0.03-0.40 mg.kg^-1 and 0.00-0.16 mg.kg^-1 respectively. The levels of dichlorodiphenyltrichloroethane (DDT) and derivatives in rice ranged between 0.13 and 0.23 mg.kg^-1, whilst methoxychlor had 0.08 mg.kg^-1 in rice.  Some pesticide residues (6 in oats and 5 in rice) were detected at levels higher than their maximum residue levels (MRLs) prescribed by the Food and Agricultural Organization/World Health Organization (FAO/WHO) and the European Union (EU). The health quotient (HQ) levels of heptachlor in rice for both adults (HQ = 1.40) and children (HQ = 6.82) exceeded the threshold of health risk safety level (HQ <1) and hence may constitute non-carcinogenic health problems. The health index (HI) of pesticide residues in oat for children (HI = 2.957), as well as rice samples for both adults (HI = 1.576) and children (HI = 7.695) exceeded the threshold health safety mark (HI<1) and hence would be described as not safe for consumption over a lifetime.