Carcinogen Risk Assessment of Polycyclic Aromatic Hydrocarbons in Drinking Water, Using Probabilistic Approaches

Background: This study was focused on the probability of carcinogen risk of low-level ingestion and dermal exposure with polycyclic aromatic hydrocarbons (PAHs) from drinking water in Tehran, capital of Iran. Methods: Concentrations of 16 PAHs were measured in the tap, bottled and heated tap water in four different seasons. Using a questionnaire-based survey, exposure with PAHs from drinking water was evaluated via direct ingestion, swimming, washing and showering. Finally, a comprehensive risk assessment was performed in four age groups. Rank correlation was used to represent variability in risk analysis and obtained coefficients were used for sensitivity analysis. In addition, Monte Carlo simulation was implemented to determine risk probability distributions and to calculate cumulative probability of the total risks in different age groups. Results: The lifetime average daily dose and the dermal absorbed dose were 0.69E-06 and 1.33E-05 mg/kg/day, respectively. The total estimated excess lifetime cancer risk (ELCR) of ingestion and dermal exposure were 1.57E-05 and 17.24E-05. Conclusion: Sum of estimated ingestion and dermal ELCR was 18.81E-05, which was higher than the acceptable value recommended by WHO. It means a total of 1504 lifetime cancer cases in residents of Tehran. Monte Carlo simulation indicated that risk probability above the acceptable level was 96.2% in dermal exposure. Moreover, sensitivity analysis indicated that tap water consumption (P-spearman > 0.92) and washing activities (P-spearman > 0.95) had the greatest correlation on the cancer risk.