Distribution Of And Health Risk Assessment On Brominated Flame Retardants In Typical Water Units In The Middle Reaches Of The Yangtze River

Polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs) are two subfamilies widely used in flame retardants and two kinds of pollutants of great concern in the present study. From the year of2000, the domestic demand of PBBs and PBDEs has increased at a rate of8%per year in China. Due to the lack of chemical bond binding, PBDEs and PBBs can enter the environments through production, utilization, and dismantling of the electronic products, and endanger the safety of the environment. The effects of PBBs and PBDEs on environment and humanbody were found to be essentially similar to those of PCBs.This thesis established an analytical method on GC-MS/MS for PBDEs and PBBs in samples of sediments, fishes and plants. Surface sediments, fish muscles and plant leaves in typical water units in the middle reaches of the Yangtze River from Chongqing to Yichang were analyzed and discussed. Similar samples containing PBDEs and PBBs both in China and in other countries were compared, and the estimated cumulative cancer risk were discussed for the local residents who eat fishes from the Yangtze River. The main conlusions from the experiments were summarized as follows.1. Analytical method for27PBDE congeners and22PBB congeners on GC-MS/MS was established for samples of sediments, fish muscles and plant leaves. This paper optimized pretreatment method on analysis of27PBDE congeners and22PBB congeners in sediments, fishes, and plant leaves, and then chose the best ASE, GPC and GC/MS/MS conditions, discussed linear equations, correlation coefficients, method detection limits, average recovery, and relative standard deviations for27PBDE congeners and22PBB congeners by NCI, and analyzed concentrations of49BFR congeners in28surface sediments,24fish muscles and27plant leaves.2The results showed that the average concentration of22PBB congeners was26.25pg·g-1·dw in sediments (varied between0.52and138.62),110.93pg·g-1·dw in fish muscles (varied between30.53and563.44), and84.19pg·g-1·dw in plant leaves (varied between19.65and288.21), respectively. The average concentration of27PBDE congeners was63.10pg·g-1·dw in sediments (varied between ND and648.70),112.47pg·g-1·dw in fish muscles (varied between20.61and789.32), and84.19pg·g-1·dw in plant leaves (varied between15.47and454.75), respectively.3PBB1, PBB31and PBB103in PBBs were found as the most predominant pollutants in the samples in the studied area. On the other hand, low contents of PBB209were detected in Three Gorges Reservoir. Such finding was consistent with the fact that a large amount of low-brominated PBBs were used as flame retardants in market, which implies that the PBB209congener could degraded by photolytic degradation and microbial degradation to low-brominated PBBs. The results showed that PBBs used in commercial products might be the main source of PBBs in this region.4BDE28, BDE47, BDE77and BDE99in low-brominated PBDEs were found having higher detective frequency and higher concentrations, and were the most predominant pollutants of PBDEs congeners in this region. A certain level of BDE209was also found in Three Gorges Reservoir. Studies indicated that BDE28was the main degradation product of BDE47in surfactants show that BDE28can from high-brominated PBDEs. High levels of BDE47,77and99in Octa-BDE prove BDE28,47,77and99may came from Octa-BDE and Penta-BDE used in commerce. BDE209can be degraded easily through exposure to light and through biological activity in the environment, therefore, it is possible that PBDEs used in commercial products like textile and circuit board (Deca-BDE) might be the main source of BDE209in this study area.5Correlation analysis revealed Oxidation-Reduction Potential (ORP) weekly influenced the concentrations of BFRs in sediments. The concentrations of BFRs in the studied area were at a relative low level compared with those in the sedimens, fishes, and plant leaves from other countries. The estimated cumulative cancer risks caused by PBBs and BDE209were1.97x10-7and1.86x10-12, respectively, for the local residents who eat fishes from the studied area, which shows that cancer risk is negligible due to PBBs and BDE209contamination in fish samples.