Harrad Stuart, Abdallah Mohamed Abou-Elwafa, Covaci Adrian
Division of Environmental Health and Risk Management, School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, B15 2TT, UK.
Environ Int. 2009 Apr;35(3):573-9. doi: 10.1016/j.envint.2008.10.005. Epub 2008 Dec 5.
The temporal evolution of concentrations of alpha-, beta-, and gamma-hexabromocyclododecanes (HBCDs), and pentabromocyclododecenes (PBCDs--degradation products of HBCDs) was studied in separate aliquots of a well-homogenized indoor dust sample. These were: (a) exposed to natural light, and (b) kept in the dark. Results revealed a rapid photolytically-mediated shift from gamma-HBCD to alpha-HBCD that was complete after 1 week of exposure, and a slower degradative loss of HBCDs via elimination of HBr. Under the specific conditions studied in this experiment, calculated half-lives (t(1/2)) showed the decay in SigmaHBCDs concentration was faster in light-exposed samples (t(1/2)=12 weeks), than in light-shielded dust (t(1/2)=26 weeks). Within-room spatial and temporal variability in concentrations and diastereomer patterns were studied in six and three rooms respectively. While in some rooms, little variability was detected, in others it was substantial. In one room, concentrations of SigmaHBCDs and the relative abundance of gamma-HBCD declined dramatically with increasing distance from a TV. The same TV appears to have influenced strongly the temporal variation in that room; with higher concentrations observed in its presence and when the TV was moved closer to the area sampled. Significant negative correlation was observed in one room between concentrations of SigmaHBCDs and dust loading (g dust m(-2) floor), implying "dilution" occurs at higher dust loadings.
在一份充分均质化的室内灰尘样本的不同等分试样中，研究了α-、β-和γ-六溴环十二烷（HBCDs）以及五溴环十二烯（PBCDs，HBCDs的降解产物）浓度的时间演变。这些等分试样分别：（a）暴露于自然光下，（b）保存在黑暗中。结果显示，在光照介导下，γ-HBCD迅速向α-HBCD转变，暴露1周后转变完成，并且通过消除HBr，HBCDs的降解损失较为缓慢。在本实验所研究的特定条件下，计算得出的半衰期（t(1/2)）表明，暴露于光照下的样本中ΣHBCDs浓度的衰减更快（t(1/2)=12周），而避光灰尘中的衰减则较慢（t(1/2)=26周）。分别在六个房间和三个房间中研究了室内浓度和非对映异构体模式的空间和时间变异性。虽然在一些房间中检测到的变异性很小，但在其他房间中变异性很大。在一个房间里，ΣHBCDs的浓度以及γ-HBCD的相对丰度随着与一台电视机距离的增加而显著下降。同一台电视机似乎对该房间的时间变化产生了强烈影响；在电视机开启时以及将电视机移近采样区域时，观察到浓度更高。在一个房间中，ΣHBCDs浓度与灰尘负荷（克灰尘/平方米地板）之间观察到显著的负相关，这意味着在较高的灰尘负荷下会发生“稀释”。
