Glyphosate Residue Concentrations in Organically and Chemically Grown Maize Grains in Selected Local Government Areas in Adamawa State, Nigeria: Health Risk Assessment

Abstract

This study investigated glyphosate residue concentrations in organically and chemically grown maize grains in selected Local Government Areas in Adamawa State, Nigeria, and assessed the potential health risks associated with dietary exposure. A total of nine locations (Song, Yola, Mubi, Gombi, Michika, Ganye, Numan, Hong, and Maiha) were included, with maize samples analysed using high-performance liquid chromatography (HPLC). estimated daily intake (EDI) and health risk index (HRI) were calculated for both adults (60 kg body weight) and children (16.7 kg body weight) based on the maize consumption rate of 0.1659 kg/day and a glyphosate Acceptable Daily Intake (ADI) of 1.0 mg/kg bw/day. Results revealed that chemically grown maize consistently contained significantly higher glyphosate concentrations (ranging from 8.1173 mg/kg in Ganye to 13.0538 mg/kg in Numan) compared to organically grown maize (ranging from 2.2272 mg/kg in Gombi to 7.7131 mg/kg in Numan). All chemically grown maize samples exceeded the maximum residue limit (MRL) of 5 mg/kg, with exceedances ranging from 62.35% to 161.08%. Organic maize samples from Mubi North, Ganye, Numan, and Maiha also exceeded the MRL. All calculated HRI values remained below 1, indicating no immediate non-carcinogenic health risk under the assessed exposure scenario. However, children exhibited approximately 3.59 times higher HRI values than adults, and chemically grown maize showed 1.69 to 5.61 times higher glyphosate concentrations than organic maize. The study concluded that, while estimated dietary risks are currently below levels of concern, the widespread MRL exceedances, particularly in chemically grown maize, represent significant food safety and regulatory compliance concerns requiring urgent attention.