Risk Assessment of Polycyclic Aromatic Hydrocarbons in Foreign and Local Rice Consumed in South East Nigeria

Abstract

Polycyclic aromatic hydrocarbons are group of organic compounds known for their carcinogenic and genotoxic nature and generated from incomplete burning of organic materials. Rice is one of the staple foods commonly consumed by both genders of all ages in Nigeria. Both local and foreign rice can be obtained from every nook and cranny of the country. The study aimed at determining the quantity of polycyclic aromatic hydrocarbons in foreign and local rice consumed in South East Nigeria; estimating the daily intake amount and the health risks associated with the consumption among adult male and female individuals in South East Nigeria. The samples were analyzed of sixteen PAHs contamination levels using gas chromatography coupled flame ionization detector. The result showed that the ∑16 PAHs concentrations in the foreign and local rice ranged from (24.103 to 26.933) × 10¯² µg/kg and (22.953 to 32.662) × 10¯² µg/kg respectively. The concentrations of ∑8 carcinogenic PAHs in the foreign and local rice ranged from (9.728 to 12.398) × 10¯² µg/kg and (11.262 to 11.717) × 10¯² µg/kg respectively. The mean concentration levels ( × 10¯² µg/kg) of lower molecular weight, LMW PAHs ranged from 9.382±2.474 in Indian rice to 12.448±5.883 in Thailand while that of higher molecular weight, HMW PAHs ranged from 14.238±6.945 in Thailand to 16.377±6.316 in Royal. The dietary intakes of the 16 PAHs were estimated, using the suitable indicators: BaP, PAH2, PAH4, PAH8. The total dietary exposure of adult male individuals (× 10¯² µg/kg bw/day) for all the indicators was 31.94 in foreign and 33.86 in local rice, and for adult female 37.24 in foreign and 39.52 in local rice. This showed that both individuals are more exposed by consuming local rice than foreign rice. It also indicated that adult female individuals have higher intakes and are therefore more exposed to health risk than adult male individuals. Margin of exposures, MOEs, was used to assess the health risk of dietary exposure. This was calculated using the expected daily intake, EDI and benchmark dose level, BMDL10 for BaP, PAH2, PAH4 and PAH8. The values obtained were much higher than 10,000 indicatng a low concern for consumer health at the mean estimated dietary exposures. The PAHs values detected were all below 1.0 µg/kg which is the permissible limit established by EFSA.