Superfund Research Program
Identification of Remediation Technologies and Conditions that Minimize Formation of Hazardous PAH Breakdown Products at Superfund Sites
During 2010, Dr. Simonich's research groupo published six manuscripts, including ones on inhalation exposure to PAHs and lung cancer risk of the Chinese population, environmental concentrations of PAHs, and emissions of PAHs from various fuel sources. A summary of the research conducted under this project was presented at the SRP's Annual Meeting in Portland, Oregon. The 2008 Beijing Olympic Games provided a unique case study to investigate the effect of source control measures on the reduction in air pollution and associated inhalation cancer risk in a Chinese megacity. The research group measured 17 carcinogenic polycyclic aromatic hydrocarbons (PAHs) and estimated the lifetime excess inhalation cancer risk during different periods of the Olympic Games to assess the effectiveness of source control measures in reducing PAH-induced inhalation cancer risks. PAH concentrations were measured in Beijing Olympic PM2.5 samples, and the associated inhalation cancer risks were estimated using a point-estimate approach based on relative potency factors (RPF). The lifetime excess cancer risk due to exposure to the 17 carcinogenic PAHs (12 priority pollutant PAHs and 5 high molecular weight (MW 302) PAHs) was estimated to range from 6.5 to 518 per million people for the source control period concentrations and from 12.2 to 964 per million people for the non-source control period concentrations. This would correspond to a 46% reduction in inhalation cancer risk due to source control measures, if these measures were sustained over time. Benzo[b]fluoranthene, dibenz[a,h]anthracene, benzo[a]pyrene, and dibenzo[a,l]pyrene were the most carcinogenic PAH species measured, and the total excess inhalation cancer risk would be underestimated by 23% if the 5 MW 302 PAHs were not included in the risk calculation. The researchers’ results suggest that source control measures, such as those imposed during the 2008 Beijing Olympics, can significantly reduce the inhalation cancer risk associated with PAH exposure in Chinese megacities and that MW 302 PAHs are a significant component of the overall inhalation cancer risk in China. In 2010, the research group continued collaborations on PAH photochemistry at Université de Bordeaux. In addition, five graduate students, including one from the Chinese Academy of Science in Guangzhou, and one postdoctoral fellow were trained.