Model Analysis On Population Inhalation Exposure To Polycyclic Aromatic Hydrocarbons And Associated Lung Cancer Risk

The incidence and mortality of lung cancer have been increasing rapidly in the lastthree decades in China. Polycylic aromatic hydrocarbons (PAHs) are a knowncarcinogen in ambient air and their pollution in China’s atmosphere is very heavy. Toquantitatively assess the lung cancer risk due to PAH inhalation exposure is veryimportant to address the pollution in China and to make effective control strategies.The core of this study was to establish suitable model for population inhalationexposure to PAHs. As the first step, the concept of exposure coefficient was introducedto explain the geographical heterogeneity found in China Air Pollution and HealthEffects Study. The results showed significant correlation between the PM10exposurecoefficients and mortality coefficients, underscoring the importance of indoorenvironment and ventilation condition on exposure estimates. This concept was furtherdeveloped into a population exposure model for PAHs. This model used a2-stageMonte Carlo simulation framework, consisted of a core of indoor PAH concentrationmodel and could quantitatively assess population inhalation exposure to PAHs and theassociated lung cancer risk. The indoor concentration simulation module was evaluatedagainst avalaible experiments and showed good accuracy in model prediction. And theapproapriateness of adopting Monte Carlo framework for indoor concentrationsimulation was validated in an experiment. This study took Beijing region in2006as anexample to demonstrate the use of the proposed model. Parameters related to thiscalculation were collected, including demographical information, meteorlogicalparameters, outdoor PAH and particle concentrations, indoor PAH and particle sourcesand emission factors, etc. The analysis showed that, the popolulation attributablefraction (PAF) of lung cancer rik due to exposure to PAHs in Beijing was2.99%(95%confidence interval:1.75%-4.26%), and the exposure pattern analyses showed thatindoor exposure to outdoor originated PAHs was the dominating exposure pattern forurban residents while indoor sources played an important role in determining ruralresidents’ exposure. This population exposure model was further applied toquantitatively compare and analyze various intervention strategies for PAH inhalationexposure. A total of thirteen strategies in five different categories were assessed in termsof their performance in reducing indoor PAH concentration, controlling annual dose and alleviate lung cancer risk. This analysis showed a good practice of the application of thepopulation exposure model established in this study.