Profiling of seasonal variation in and cancer risk assessment of benzo(a)pyrene and heavy metals in drinking water from Kirkuk city, Iraq

Water samples at 13 sites were analyzed to evaluate heavy metals (cobalt, lead, manganese, copper) and benzo(a)pyrene using 2 methods of analysis (high-performance liquid chromatography (HPLC) and enzyme-linked immunosorbent assay (ELISA) kits). The Lesser Zap River is the main tributary of the Tigris and is used as a main source of drinking water in Kirkuk city through the General Kirkuk project. Risk evaluation for benzo(a)pyrene and lead in water samples was accomplished by Monte Carlo simulation. The highest concentrations of B(a)P were recorded at sites S7 and S5, with levels of 0.192 and 0.122 µg L−1 detected by HPLC and ELISA, respectively. The WHO guidelines for benzo[a]pyrene in drinking water recommend 0.7 µg L −1, and none of the samples surpassed this level; moreover, B(a)P levels exceeded EPA standards in 2014 (0.01 µg L−1), particularly when the liquid–liquid extraction method with HPLC was used. Carcinogenic risks for human adults and children exist and are highest during the rainy season as compared with the carcinogenic risk during the dry season and risks for children exceed those of adults. This indicates that the 2nd round of sampling (winter season) harbors more carcinogenic risk than the 1st round of sampling (dry season).