Substance flow analysis of antimony for risk assessment of antimony and antimony compounds in Japan

Antimony trioxide is a possible carcinogenic compound that affects humans through inhalation exposure. Therefore, antimony and antimony compounds were included in Class I of the Pollutant Release and Transfer Register (PRTR) list in Japan. In this study, the substance flow analysis of antimony, from its production to final disposal, was performed. The amounts of domestically supplied antimony, stocked antimony, and generated waste containing antimony were estimated for the period from 1970 to 2015 in order to conduct risk assessment of antimony and antimony compounds. Sensitivity analysis was also conducted in order to identify how the uncertain parameters affect the target values for sensitivity analysis in the substance flow of antimony. The amount of domestic waste generated was estimated to be ten thousand tons per year in 2015, which was nearly equal to the amount of domestic supply for the same year. The amount of recovered antimony was estimated to be over three times the amount in 2001, and it was strongly affected by policies relating to the sound material cycle society, particularly the Electric Appliance Recycling Law enacted in 2001. On the basis of this study, it was also concluded that the main source of emission into the air was automotive brake abrasion dust and the amount of emission was estimated to be around 100 t/year in 2001. Furthermore, the amount of emission into the air was largely controlled by two factors, the expected lifetime and future trend of the domestic supply of brake pads.