Objective: A risk assessment and dietary exposure to polycyclic aromatic hydrocarbons (PAHs), lead and cadmium from bread, a common food consumed in Nigeria.
Material and methods: Sixty samples of bread were collected from different types of bakeries where the heat is generated by wood (42 samples) or by electricity (18 samples) from twenty bakeries located in Gusau Zamfara (B1- B14) and Port Harcourt Rivers States (B15-B20) in Nigeria. PAHs in bread were determined by gas chromatography. Lead and cadmium were determined using atomic absorption spectrophotometry.
Results: Non-carcinogenic PAHs pyrene (13.72 μg/kg) and genotoxic PAHs (PAH8), benzo[a]anthracene (9.13 μg/ kg) were at the highest concentrations. Total benzo[a]pyrene concentration of 6.7 μg/kg was detected in 100% of tested samples. Dietary intake of total PAHs ranged between 0.004-0.063 μg/kg bw. day-1 (children), 0.002-0.028 μg/kg day-1 (adolescents), 0.01-0.017 μg/kg day-1 (male), 0.002-0.027 μg/kg day-1 (female), and 0.002-0.025 μg/kg day-1 (seniors). The Target Hazard Quotient (THQ) for Pb and Cd were below 1. Lead ranged from 0.01-0.071 mg/kg with 10.85 and 100% of bread samples violating the permissible limit set by USEPA, WHO and EU respectively. Cadmium ranged from 0.01-0.03 mg/kg, with all bread samples below the permissible limits as set by US EPA, JECFA and EU. The daily intake of Pb and Cd ranged from 0.03-0.23 μg/kg bw day-1 and 0.033-0.36 μg/kg bw day-1 respectively. Incremental lifetime cancer risk (ILCR) was 3.8 x 10-7.
Conclusions: The levels of these contaminants in bread if not controlled might present a possible route of exposure to heavy metals and PAHs additional to the body burden from other sources.
Keywords: bread; polycyclic aromatic hydrocarbons; lead; cadmium; risk assessment; Nigeria.