Determination of Polycyclic Aromatic Hydrocarbons (PAHs) Contamination Levels in Underutilized Grains (Guinea Corn, Pigeon Peas and Bambara Nut) in South East Nigeria

Abstract

Polycyclic aromatic Hydrocarbons, PAHs are harmful persistent organic pollutants formed by incomplete combustion of organic matter. They are carcinogenic and mutagenic and can occur in foods. These underutilized grains-guinea corn, pigeon peas and bambra nut are commonly consumed in South East Nigeria. This study aimed to quantitatively determine the polycyclic aromatic hydrocarbons contamination levels in these underutilized grains (guinea corn, pigeon peas and bambara nut) commonly consumed in Eastern part of Nigeria. The sixteen PAHs were determined in the grain samples using gas chromatography coupled with flame ionization detector, GC-FID after extraction by sonication. The concentrations (×10 -2 µg/kg) of ∑16 PAHs in the analyzed samples were in the range of 24.07 to 36.49 in red guinea corn and red pigeon peas respectively. The lower molecular weight polycyclic aromatic hydrocarbons, LMW-PAHs total mean concentrations (×10 -2 µg/kg) varied from 6.217±0.442 in red guinea corn to 10.423±6.661 in pure white bambara nut at the percentages of 25.83% and 33.51% respectively. While the high molecular weight polycyclic aromatic hydrocarbon, HMW-PAHs varied from 14.835±7.178 to 27.657±14.190 respectively in white pigeon peas and red pigeon peas at the percentages of 59.34% and 75.79%. The total mean concentration levels (×10 -2 µg/kg) of ∑8 carcinogenic PAHs in samples ranged from 10.913±4.215 in white pigeon peas to 17.444±7.023 in red pigeon peas. The sixteen priority PAHs were detected in all the samples at a very low level, below the maximum allowable limit-1.0µg/kg established by European Food Safety Authority, EFSA for cereals and cereal-based products. But this can be harmful to human being at long time accumulation in the body. Permissible limit of PAHs in legume grains should also be established.

Technical Report on the notification of dried seeds and flour thereof of Vigna subterranea (L.) Verdc. as a traditional food from a third country pursuant to Article 14 of Regulation (EU) 2015/2283

“…EFSA notes that considering the process applied to produce the flour, PCBs and PAHs are expected to be present in comparable amounts in the seeds. A publication retrieved by EFSA reported sums of PAHs at around 0.31-0.33 μg/kg in seeds of bambara groundnut (Odika et al, 2022). No maximum levels are set for PCBs and PAHs in Commission Regulation (EU) 2023/915 for legume vegetables or groundnuts.…”