Formalin in imported frozen fish products in Bayelsa State, Nigeria: effects of heat treatments on the concentration and health risk assessment

Abstract

Fish make up an essential component of daily diets due to their nutritional composition. In this study, formalin concentration in imported  fish products in Bayelsa State, Nigeria, was undertaken. The effect of household heat processing treatments on the formalin  concentrations, and the potential risk associated with consumption of these fish products, were evaluated. Fish products of different  species were obtained from wholesale and retail outlets, and were prepared as raw, cooked, fried and smoked samples. Formalin was  extracted from the prepared fish samples using a mixture of acetone and dichloromethane, and quantified using GC-MS. The average  daily intake (ADI) of formalin was used to estimate potential health risk. Results showed low concentration of formalin in the raw fish  samples, while heat processing treatments (frying and boiling) significantly elevated formalin concentrations. The formalin  concentrations of heat processed fish samples with respect to the raw samples followed the order: smoked < raw < boiled < fried; and  raw < smoked < boiled < fried for wholesale and retail products respectively. However, all formalin concentrations were below guideline  values. The ADI of formalin were below established guideline values, suggesting that the intake of formalin in fish before and after  household heat processing treatments may not pose significant risk to consumers of the imported frozen fish products.