title: Factors influencing atmospheric concentrations of polybrominated diphenyl ethers in Japan.
abstract: We used polybrominated diphenyl ether (PBDE) data in air at 38 sites across Japan (2009-2012), which were measured by the Japan Ministry of Environment (JMOE), to elucidate the time trend and seasonality of atmospheric PBDEs. In order to address few (7% for BDE-47) to many (63% for BDE-153 and 183) non-detect data, Tobit model, also called a censored regression model was used. The model revealed that the concentrations of PBDE congeners were influenced by a combination of year, temperature, rainfall rate, and population density. Greater declines were observed for BDE-47, -99, -153 and -183 (-21, -25, -17, -23%/year, p < 0.05) than for BDE-209 (-6%/year, p = 0.065). These trends were consistent with the estimated trends of penta-, octa- and deca-BDE contained in in-use products based on domestic demand for PBDEs in Japan and product lifespan. Seasonal patterns were opposite for light congeners (BDE-47 and -99), which increased with temperature, and heavy congeners (BDE-183, and -209), which decreased with temperature. Temperature-dependent emission (evaporation) for light congeners and temperature-independent emission (abrasion) for heavy congeners, coupled with seasonality of atmospheric boundary layer height, might explain these seasonal patterns. Human population density showed a positive correlation with all PBDE congener concentrations, whereas PBDEs showed negative correlation with rainfall rate.
authors.affiliation: Environment Preservation Research Center, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Nguyen Thanh
authors.initials: NT
authors.lastname: Dien
authors.affiliation: Environment Preservation Research Center, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan. Electronic address: hirai@eprc.kyoto-u.ac.jp.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Hirai
authors.affiliation: Nippon Steel & Sumikin Technology Co. Ltd., Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Miyazaki
authors.affiliation: Environment Preservation Research Center, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Sakai
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D004784:Environmental Monitoring; D055768:Halogenated Diphenyl Ethers / Q000032:analysis*; D006801:Humans; D007564:Japan; D011075:Polybrominated Biphenyls / Q000032:analysis*; D011156:Population Density; D011891:Rain; D013696:Temperature
chemical_list: D000393:Air Pollutants; D055768:Halogenated Diphenyl Ethers; D011075:Polybrominated Biphenyls; C517828:hexabrominated diphenyl ether 153
keywords: Atmospheric PBDE; Non-detect value; Panel data analysis; Seasonal trend; Temporal trend; Tobit model