O-108 Assessment of the Incremental Lifetime Cancer Risk by Who and Us-Epa Criteria for the Contribution of Pm 2,5 Bounded Carcinogenic Pahs Inside a University Classroom in Rome

Introduction Directive 2004/107/EC identifies annual 1 ng/m3 benzo(a)pyrene (BaP) as the air quality indicator for PAHs. The WHO still assumes the BaP for estimating the Incremental Lifetime Cancer Risk (ILCR). Instead, US-EPA for the ILCR takes into account the contribution of individual PAHs to total carcinogenic potency (TCP). Methods WHO and the US EPA criteria were applied to assess the contribution to the ILCR of PM2,5-bound carcinogenic PAHs inside a classroom of the Sapienza University of Rome and outdoors. Aggregating data according to weekdays (WD) and weekends (WE), it allowed distinguishing the contribution by working and non-working days. WHO ILCR was calculated from the BaP concentration and the carcinogenic risk unit (UR) 8.7x10-5 ng/m3); that of US-EPA, from the TCP concentration and the carcinogenic unit risk of inhalation (URI) 6.4x10-7 ng/m3. The contribution of individual congeners to carcinogenic potency was also calculated (%potency). Results and discussion BaP_WE concentrations were similar to those of BaP_WD, while TCP concentrations about 1.15 higher, indoors and outdoors. ILCRs_WHO were approximately 60 times ILCRs_US-EPA. BaP and DahA contributed about 80% to the carcinogenic potency of the mixture, with the greatest contribution given by BaP_WD. Conclusion ILCRs for indoor carcinogenic PAHs from outdoor on working and non-working days show that the WHO criterion BaP based is more protective in representing the carcinogenic risk of the mixture. The US-EPA criterion, while considering the contributions of individual congeners, returns lower ILCR values, being however more sensitive to variations between weekdays and weekends, better reflecting the different contribution of external sources.