| Polycyclic aromatic hydrocarbons（PAHs）have widely attracted public attention due to their persistence,semi-volatile,bioaccumulative and long-term residue in the environment.In particular,PAHs are included in the Protocol to the Convention on Long Range Transboundary Air Pollutants due to their long-range transportation ability.PAHs can not only migrate and diffuse through traditional environmental media such as atmosphere and water,but also redistribute and transfer through trade of products and services.Scholars have conducted extensive research on the atmospheric transport and source-sink relationship of PAHs.However,there are few studies on the transfer of PAHs emissions embodied in trade and the impact on human health risks.In this study,the production-based atmospheric emissions inventory of 2004 and2014 for 16 PAH congeners listed as priority control by USEPA was established based on the energy consumption of 207 countries and emission factor of PAHs.The GTAP database and the multiregional input-output（MRIO）model were applied to calculate consumption-based emissions of PAHs and the transfer of PAHs embodied in global trade.The structural decomposition analysis（SDA）was used to quantitatively analyze the contribution of each driving factor to the change of consumption-based PAHs emission from 2004 to 2014.Benzo（a）pyrene（Ba P）was selected as the representative of carcinogenic PAHs,and the Can METOP atmospheric transport model was used to simulate the impact of global trade on Ba P atmospheric concentration in 2004 and 2014.Finally,based on the simulated Ba P atmospheric concentration and Incremental Lifetime Cancer Risk（ILCR）model,the impact of risk due to inhalation exposure to Ba P driven by global trade was evaluated.The main results were as follows:（1）The estimated global production-based PAH emissions were 171274 tonnes in2004 and 150049 tonnes in 2014.The greater PAHs emissions are mainly concentrated in less-developed countries,and the largest production-based PAH emissions were found in China with 38407 tonnes in 2004 and 47228 tonnes in 2014.The global consumption-based PAH emissions were 164231 tonnes and 144255 tonnes.Compared with 2004,the production-and consumption-based PAH emissions were decreased in2014.Overall,the production-based PAH emissions were greater than that of consumption-based in less-developed countries,while the opposite patten in developed countries.（2）Compared with 2004,the global consumption-based PAH emissions decreased by 19976 tonnes in 2014.The final demand level was the strongest driving factor for the growth of consumption-based PAH emissions,accounting for 53.4%of consumption-based emissions,followed by population（8.57%）,production input structure（5.71%）,and final demand structure（7.51%）,and the emission intensity was the key factor in the reduction of consumption-based PAH emissions.（3）China was the largest net virtual PAH exporters in the world,and the net virtual PAH emissions were 9057 tonnes and 8964 tonnes in 2004 and 2014,accounting for29.1%and 54.7%of the total net virtual PAH emissions,respectively.In 2004,the largest net virtual PAH flow was from China to the USA（4071 tonnes）,followed by China to Western Europe（2850 tonnes）,and Southeast Asia to Western Europe（2624tonnes）.The virtual PAH flows embodied in global trade significantly decreased in2014 compared to 2004.The largest net PAH flow was from China to the USA（2626tonnes）,followed by China to Western Europe（2183 tonnes）,and Eastern Europe to Western Europe（1156 tonnes）in 2014.（4）The higher Ba P atmospheric concentrations from the TRADE scenario were found in China and India,and Ba P atmospheric concentrations in less developed countries were overall higher than that in developed countries.In the NO＿TRADE scenario,the Ba P atmospheric concentration in developed countries were higher than that in the TRADE scenario.The global trade reduced annually average atmospheric concentrations of Ba P of 5.12×10-2 ng/m3 in Western Europe,1.13×10-2 ng/m3 in the USA,and 9.86×10-3 ng/m3 in the rest of East Asia,while enhancing 1.36×10-2 ng/m3 in China and 4.95×10-3 ng/m3 in India.It shows that global trade aggravates the Ba P atmospheric contamination in less developed countries,while decreasing that in developed countries.（5）The estimated number of global lung cancer cases due to inhalation exposure to Ba P atmospheric concentration were 11315 in 2004 and 11964 in 2014.Among these cases,7086 and 7010 occurred in China in 2004 and 2014,and 1588 and 3379 occurred in India for the same periods.Those cases accounted for 76.7%and 86.8%of the total number of global lung cancer cases.Western Europe was the largest contributor to lung cancer cases elsewhere due to trade of goods and services,which contributed to 21.2%of lung cancer cases in Eastern Europe,15.5%in Southeast Asia,13.1%in Russia,and11.3%in the Middle East and North Africa in 2004.For the same period,the USA also contributed to 11.1%of lung cancer cases in Canada,10.8%in Latin America,10.8%in Southeast Asia,and 8.7%in China.Overall,global trade increased lung cancer cases worldwide to 1147 in 2004 and 1735 in 2014.PAHs emissions are transferred from developed to less-developed regions due to global trade,especially to densely populated China and India.The global trade increased the PAHs atmospheric pollution and human inhalation exposure risk of Ba P in less-developed countries,but decreased that in developed countries.The results could help clarify the responsibilities of consumers and producers associated with global trade-driven PAH emission transfer.Our study could provide a useful reference for global collaboration in the reduction of PAH pollution and related health risks. |
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