Air Pollution and Human Health Risk: Evaluation of Carcinogenic Potential of Urban Airborne Particulate Matter

Urban airborne particulate matter (PM) is known to increase morbidity and mortality due to cardiopulmonary diseases related to inflammatory processes and genotoxic effects. The aim of this thesis is to highlight the toxic and carcinogenic potential of airborne particulate matters collected during different seasons at a site that is located in the northern area of the city of Bologna by using alternative in vitro tests, such as the cell transformation assay with BALB/c 3T3 A31-1-1 and Bhas 42 cells. The purpose is also to evaluate the lifetime cancer risks associated with air inhalation in different sites (rural and urban), by using the relative potency of compounds belonging to the same chemical class (PAHs and nitro-PAHs) and the specific unit of carcinogenic risk. None of the organic or inorganic extracts of PM2.5 and PM1 induced a significant increase in the average number of transformed foci/plate or in the transformation frequency of BALB/c 3T3 A311-1 cells, whereas the results obtained by Bhas 42 cell transformation showed a significant increase in the average number of transformed foci/plate. All the analyzed organic extracts showed promoting effects in Bhas 42 cells. The application of the UR cancer risk to the transformed value of B(a)P equivalents in the winter– autumn campaigns leads to estimate an increase in the cancer risk similar to that defined in the literature (1 x 10-4 for exposure to 1 ng/m3). The calculated cancer risk was about one order of magnitude lower in the summer campaigns. In conclusion, the proposed approach, based on the integration of the data derived from in vitro testing and cancer risk assessment, could represent a reliable model for investigating environmental mixtures and predicting their effects on toxicological relevant endpoints.