ARTICLE pubs.acs.org/est
Polybrominated Diphenyl Ethers and Polychlorinated Dibenzop-dioxins and Dibenzofurans in Surface Dust at an E-Waste Processing Site in Southeast China Anna O. W. Leung,† Jinshu Zheng,† Chik Kin Yu,† Wing Keung Liu,‡ Chris K.C. Wong,† Zongwei Cai,§ and Ming H. Wong†,^,* †
Croucher Institute for Environmental Sciences, and Department of Biology, Hong Kong Baptist University, Kowloon Tong, Hong Kong, PR China ‡ School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, PR China § Dioxin Analysis Laboratory, and Department of Chemistry, Hong Kong Baptist University, Hong Kong, PR China
bS Supporting Information ABSTRACT: Surface dust collected from printed circuit board recycling workshop floors, roads, a schoolyard, and an outdoor food market in Guiyu, China, a village intensely involved in e-waste processing, were investigated for levels of polybrominated diphenyl ethers (PBDEs) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). PBDE concentrations in dust from workshop-floors (14 800 ( 5130 ng/g) and on adjacent roads to the workshops (24 900 ( 31 600 ng/g) were highest among the study sites whereas PCDD/F concentrations were highest at the schoolyard (1316 pg/g) and in a workshop (1264 pg/g). Analyses of schoolyard (807 ( 190 ng/g; 6941030 ng/g) > reference sites, Gurao (328 ( 162 ng/g; 182502 ng/g) and Shantou (396 ( 65.8 ng/g; 312473 ng/g). The largest range in PBDE concentrations was found in dust collected from underneath exhaust fans (maximum concentration being 10 times higher than the minimum). The reason may be attributed to plastic computer scraps, which also contain PBDEs, found on the roads outside the workshops. Many of the results revealed large standard deviations indicating the high heterogeneous nature of the dust samples. In general, the concentrations of BDE-47, -100, -99, -154, -153 in dust collected from directly underneath exhaust fans were significantly higher (p < 0.05) than dust from the road, schoolyard, open food market, plastic chips drying district, and the two reference sites. Only concentrations of BDE-100 and BDE-99 in the exhaust fan dust were significantly higher than in workshopfloor dust. The average concentration of BDE-28 in dust collected from workshop-floors was significantly higher (p < 0.05) than the other sampling locations. BDE-209 levels in dust from the plastic chips drying district and underneath exhaust fans were also found to be significantly higher (p < 0.05) than dust from the other sites. The total concentrations of the eight congeners contributed to 61.3, 66.3, 66.5, and 83.3% for the main road, workshop-floors, road at intersection and underneath exhaust fans, respectively. No significant differences were found with respect to BDE-47, -99, -100, -153, -154, and -183 among the other sites due to wide variability in the concentrations of the samples. BDE-47, -99, -183, and -209 contributed the greatest to the average total concentration. For workshop-floor dust, the highest percentages were attributed to BDE-47 (1826%), -99 (1221%), and -183 (3.123%). For dust collected underneath exhaust fans, the highest percentages were attributed to BDE-99 (2639%), -47 (1721%), and -209 (2.316%). Highest 5777
dx.doi.org/10.1021/es103915w |Environ. Sci. Technol. 2011, 45, 5775–5782
Environmental Science & Technology average percentages of BDE-209 were found in dust from the main road (15%), open food market (18%), plastic chips drying district (20%), and in road dust from Shantou University campus (26%). This was in contrast to the percentage of BDE-209 found in Guiyu soil which ranged from 35 to 82%.3 From the congener profiles (not shown), it was obvious that the source of PBDEs in the dust at Guiyu was not the same as that for the reference site because the percentage of BDE-209 was comparatively higher at the latter site. In fact, it was not surprising to detect a higher percentage of BDE-209 at the reference site because the commercial product deca-BDE is still commonly used whereas pentaBDE and octa-BDE are globally phasing out. Furthermore, the e-waste recycling areas of Guiyu generally receive high inputs of penta-BDE and octa-BDE due to the presence of these flame retardants in older e-waste. The source of PBDEs at the sampling locations in Guiyu appeared to be the same due to similarities in their congener profiles. PBDE contaminated dust from the workshops which were partially exhausted to the outside road could have been atmospherically transported (i.e., by wind) to the other study sites. Moreover, due to the heat generated from circuit board recycling, BDE-209 may have debrominated into lower brominated congeners, however, this requires further investigation. In general, the average concentrations of the eight PBDE congeners (Table 1) in dust from underneath exhaust fans and workshopfloors were significantly higher than dust from the other sampling sites in Guiyu. They contributed to an average of 67% for workshop-floor dust, 83% for exhaust fan dust and 22 and 44% for the reference sites (Gurao, Shantou, respectively). For the reference sites, the dust was dominated by high brominated compounds (BDE-206, -207, and -209) which accounted for 2151% (Gurao) and 4669% (Shantou) of the total concentrations. From the homologue profiles (Figure S2, SI), tetra-BDE and penta-BDE were prominent in the workshop-floor dusts (57%) and exhaust fan dust (77%), whereas nona-BDE and decaBDE were prominent in dust at the reference sites (45, 55%). When the average total concentrations for the two particle sizes (
