2:30 PM - 2:45 PM
[MZZ41-04] Assessment of the human health risk posed by the chemical substances contained in export products from Japan to the importing country
Keywords:Chemical pollution, Risk assessment, Export products
Export products are one of the possible routes for the transboundary movement of chemical substances from Japan, but they are not included in the scope of the PRTR system. Used products may contain chemical substances regulated by the Chemical Substances Control Law. Accordingly, the transfer of risk between countries via export products has attracted some research attention. Scholars have thus far conducted stock flow and exposure analyses, and others have evaluated the substitution of chemicals with safer substances. However, all these works were conducted in Japan, and no quantitative study has considered the risks posed by the products being exported by the country. To fill such gap, this study quantitatively assesses the human health risk posed by the chemical substances contained in export products from Japan to the importing country and to verify the effectiveness of risk reduction measures, including substance substitution.
As Japan ranked second in the world in 2019 in terms of automobile exports, automobiles were selected as the target product in this study. Decabromodiphenyl ether (DecaBDE) and antimony trioxide (Sb2O3), which are contained in plastic and textile products as flame retardants, were selected as the target chemical substances. DecaBDE has been regulated for use in automotive parts since 2012 in response to concerns about its human health risk. Meanwhile, triphenyl phosphate (TPP) was selected as the alternative to DecaBDE and Sb2O3.
First, a hierarchical cluster analysis was conducted using IBM SPSS statistics (IBM Co., Ltd.) for all 197 countries to which Japan exports its automobiles. Four datasets were used, namely, the number of automobiles exported from Japan, ratio of used automobiles to total exports, population density, and GNI per capita. The importing countries were selected based on the analysis results.
Second, a risk assessment methodology for chemical substances focusing on export products and substance substitution was designed. A substitution scenario and an un-substitution scenario were created while considering the regulations on the use of chemical substances in the exporting countries. In the substitution scenario, the TPP was used as a substitute for DecaBDE and Sb2O3 in stages from 2012 to 2020, whereas in the un-substitution scenario, DecaBDE and Sb2O3 were used without substitution throughout the same period. The volume of exports from Japan to the importing countries was then estimated based on the country’s trade statistics, and the cumulative Weibull distribution function was used to estimate the stock and disposal volumes in the importing countries. The environmental emissions were estimated based on the emission factors, and human exposure was estimated using the USE tox model (UNEP/SETAC). The human health risk for the exposed population was estimated using Disability Adjusted Life Years (DALY), a measure of the overall burden of disease. In addition, the synergistic effects of substance substitution and risk reduction measures in importing countries were evaluated, including in the case where the average usage period in the importing country was reduced by five years, the case where the importing country improved its waste management, and the case where the import of used automobiles containing regulated substances was restricted.
Japan's export partners were eventually classified into 12 groups, and Pakistan and Uganda were selected as importing countries. In the risk assessment, the DALY measures for Pakistan and Uganda in 2045 were 1.5×10-4 and 6.2×10-6 larger in the substitution scenario than in the un-substitution scenario, respectively. In addition, the DALY measures for Pakistan in 2035 for the cases of shorter average usage period and improving waste management in addition to substance substitution were 3.2×10-1 and 7.4×10-1 times larger than those for the case of substitution alone. Meanwhile, the DALY measures for Uganda in 2035 for the case of restricting the importation of used automobiles in addition to substance substitution was 2.0×10-4 times larger than that for the case of substitution alone. Furthermore, if the exposed population was equal to the population of the target countries, then the per capita DALY measures in 2022 for the case of un-substitution were 2.5×10-11 and 4.3×10-11 years in Pakistan and Uganda, respectively. These results fail to meet the WHO standard of 1.0×10-6 year per person and year.
Following the above results, although the amount of risk transferred is not at a level of concern if limited to flame retardants contained in automobiles, such amount is expected to increase when viewed in terms of a single automobile.
As Japan ranked second in the world in 2019 in terms of automobile exports, automobiles were selected as the target product in this study. Decabromodiphenyl ether (DecaBDE) and antimony trioxide (Sb2O3), which are contained in plastic and textile products as flame retardants, were selected as the target chemical substances. DecaBDE has been regulated for use in automotive parts since 2012 in response to concerns about its human health risk. Meanwhile, triphenyl phosphate (TPP) was selected as the alternative to DecaBDE and Sb2O3.
First, a hierarchical cluster analysis was conducted using IBM SPSS statistics (IBM Co., Ltd.) for all 197 countries to which Japan exports its automobiles. Four datasets were used, namely, the number of automobiles exported from Japan, ratio of used automobiles to total exports, population density, and GNI per capita. The importing countries were selected based on the analysis results.
Second, a risk assessment methodology for chemical substances focusing on export products and substance substitution was designed. A substitution scenario and an un-substitution scenario were created while considering the regulations on the use of chemical substances in the exporting countries. In the substitution scenario, the TPP was used as a substitute for DecaBDE and Sb2O3 in stages from 2012 to 2020, whereas in the un-substitution scenario, DecaBDE and Sb2O3 were used without substitution throughout the same period. The volume of exports from Japan to the importing countries was then estimated based on the country’s trade statistics, and the cumulative Weibull distribution function was used to estimate the stock and disposal volumes in the importing countries. The environmental emissions were estimated based on the emission factors, and human exposure was estimated using the USE tox model (UNEP/SETAC). The human health risk for the exposed population was estimated using Disability Adjusted Life Years (DALY), a measure of the overall burden of disease. In addition, the synergistic effects of substance substitution and risk reduction measures in importing countries were evaluated, including in the case where the average usage period in the importing country was reduced by five years, the case where the importing country improved its waste management, and the case where the import of used automobiles containing regulated substances was restricted.
Japan's export partners were eventually classified into 12 groups, and Pakistan and Uganda were selected as importing countries. In the risk assessment, the DALY measures for Pakistan and Uganda in 2045 were 1.5×10-4 and 6.2×10-6 larger in the substitution scenario than in the un-substitution scenario, respectively. In addition, the DALY measures for Pakistan in 2035 for the cases of shorter average usage period and improving waste management in addition to substance substitution were 3.2×10-1 and 7.4×10-1 times larger than those for the case of substitution alone. Meanwhile, the DALY measures for Uganda in 2035 for the case of restricting the importation of used automobiles in addition to substance substitution was 2.0×10-4 times larger than that for the case of substitution alone. Furthermore, if the exposed population was equal to the population of the target countries, then the per capita DALY measures in 2022 for the case of un-substitution were 2.5×10-11 and 4.3×10-11 years in Pakistan and Uganda, respectively. These results fail to meet the WHO standard of 1.0×10-6 year per person and year.
Following the above results, although the amount of risk transferred is not at a level of concern if limited to flame retardants contained in automobiles, such amount is expected to increase when viewed in terms of a single automobile.