Particle bound polycyclic aromatic hydrocarbons : seasonal variation, source apportionment and cancer risk estimation -

Abstract

Introduction: background and aims: Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants released into the atmosphere as a mixture of different congeners due to incomplete combustion and pyrolysis of organic matter. Many PAHs and their derivatives are strongly potent carcinogens or mutagens to humans; therefore, their quantification and source identification in the environment are continuing concerns. Some studies in Lebanon reported short-term PAH levels at different locations. However, no studies up to our knowledge, evaluated the annual average and the seasonal variation of the 16 PAHs defined by EPA as the most potent at an urban background site. Hence, this study establishes a baseline level of PAHs at an urban representative site in Lebanon, evaluates their seasonal variation, apportion their sources and ultimately estimates their lifetime cancer risk. Methods: Every six days Particle bound PAHs (P-PAHs) were sampled using a high-volume sampler at a representative urban site like AUB. The desired analytes were then extracted using an optimized method and analyzed using gas chromatography-mass spectrometry (GC-MS) Results: The results showed that PAH levels were highly variable between the seasons throughout the year of 2017. The Highest levels of total PAHs were detected during winter (13.852.32) ng-m3 while lowest levels were detected in summer (6.320.74). Consistently, the group 1 carcinogen Benzo[a]pyrene (B[a]p) followed the same trend of seasonal variation with an annual mean (0.750.23) ng-m3 lower than the annual recommended level determined by the European Union (1ng-m3). Among the different congeners of PAHs, the five-member aromatic rings known as possible or probable carcinogens were the dominant PAH congeners in the urban site. Incremental lifetime cancer risk (ILCR) scenario estimation showed that out of 106 population, one individual at this urban site would develop cancer due to daily exposure to ambient PAHs levels. PAH congeners can be emitted by differen