Quantification of Polycyclic Aromatic Hydrocarbons, Pahs in Grain Legumes from Markets in Anambra and Enugu States of Nigeria

Abstract

Polycyclic aromatic hydrocarbons are harmful persistent organic pollutants generated by the incomplete combustion of organic matter. They have a high carcinogenic and mutagenic potential since they can interfere with the normal function of DNA. Legumes also known as pulses are important staple foods not only for human food and animal feed but also an important sources of proteins, minerals, lipids, vitamins, starch, sugars and other nonstarchpolysaccharides. This study therefore determined the contamination levels of these PAHs in the staple grain legume samples from major markets eastern Nigeria. The samples which included different varieties of beans, soya beans, pigeon peas and bambara nut were purchased, picked and ground into powdered form. The extraction was by sonication and determination of sixteen priority PAHs was carried out using gas chromatography coupled with flame ionization detector, GC-FID. The PAH2 concentration levels in the analyzed samples varied from (5.98 to 8.59) × 10-2μg/kg in soya beans and bambara nut respectively with the percentages of 29.5 and 26.1 of the total PAHs. The PAH4 concentration levels ranged from (9.20 to 14.33) × 10-2μg/kg in soya beans and bambara nut respectively with 45.75% and 43.60% of the total PAHs. While the PAH8 concentrations in the samples ranged from (10.72 to 15.39) × 10-2μg/kg in beans and bambara nut respectively with 41.6% and 46.8% of the total PAHs. So bambara nut has the highest occurrence of B[a]P, PAH2, PAH4 and PAH8. The 16 PAHs were detected in all the samples, diagnostic ratio calculated showed that fuel combustion is the major source of emission. The result of TTEC for cPAHs of the analyzed legumes indicated non-toxicity of the samples. PAHs though detected at a very low concentrations in the samples can at certain significant concentration level be very dangerous to human health. There is great need for setting permissible limits for PAHs in grain legumes as in the case of cereals and cereal products.