Determination of benzo[a]pyrene levels in smoked and oil fried Lates niloticus

Polycyclic aromatic hydrocarbons (PAHs) are a large group of organic compounds included in priority pollutant lists because of their mutagenic and carcinogenic properties. Several studies have shown that exposure to benzo[a]pyrene (BaP), a member of the PAHs increases the risk of cancer. This study investigated the effects of firewood smoking and oil frying on the BaP levels in Nile perch (Lates niloticus) sold in Western Kenya. The methodology involved BaP extraction with cyclohexane and dimethylformamide-water, clean up on silica gel column and determination by high performance liquid chromatography (HPLC) using fluorescence detection. Variable levels of BaP were detected ranging from 7.46 to 18.79 μg/kg in smoked fish and 4.17 to 11.26 μg/kg in oil fried fish. These levels were further compared with the regulatory limits. All smoked fish samples were found to exceed the acceptable Maximum residual limit (MRL) of 5 μg/kg while 20% of the oil fried samples were within the acceptable limit. BaP was not detected in raw fish samples analysed. It was concluded that firewood smoking as practiced in the study areas resulted in higher levels of BaP contamination compared to oil frying.