PBDEs environmental fate

Polybrominated Diphenyl Ethers. Many of the relevant physical and chemical properties of the PBDEs are not available (see Table 4-4). Very limited data are available on the physical and chemical properties for the individual congeners. Important data, such as vapor pressure, and Henry s law constant, are necessary for the prediction of the environmental fate and transport ofPBDEs. 

In addition to OCs, PBDEs, the popular brominated flame retardants, are now a worldwide problem even in remote areas, and Asia-Pacific region is surely no exception (Ikonomou et al., 2002 Birnbaum and Staskal, 2004 Ueno et al., 2004). PBDEs are structurally similar to PCBs and DDT and, therefore, their chemical properties, persistence and distribution in the environment follow similar patterns. Studies on the environmental behavior of PBDEs are chiefly derived from Europe, North America and the Arctic. Despite the usage of vast amounts of these compounds in Asia-Pacific region, there is a paucity of data on the prevalence of PBDEs in Asian environment. Studies are necessary to identify Asian sources of PBDEs as well as to quantify emissions and document their potential environmental fate in this region. 

Jones-Otazo, H. A., Clarke, J. R, Diamond, M., Archbold, J. A., Ferguson, G., Hamer, T., et al. Is house dust the missing exposure pathway for PBDEs An analysis of the urban fate and human exposure to PBDEs. Environmental Science and Technology, 39(14) 5121-5130 (2005). 

Schenker, U., Soltermann, R, et al (2008) Modeling the environmental fate of polybrominated diphenyl ethers (PBDEs) the importance of photolysis for the formation of lighter PBDEs. Environmental Science and Technology, 42(24) 9244-9249. 

From their high n-octanol/water partition coefficient (K, ) (see Table 15) it can be assumed that PBDEs could be bio concentrated to a high extent in fish and other aquatic organisms. Recently the analysis, environmental fate, toxicokinetics, biotransformation, bio accumulation, toxicity, and environmental occurrence was reviewed by Pijnenburg et al. [249]. In the following part the bioconcentration of PBDEs in aquatic organisms, especially fish, is critically reviewed. Some information on endocrine disrupting properties of PBDEs is also presented. 

In this chapter the chemical and physical properties, production and use, analytical methods, environmental fate and occurrence and the toxicology of PBBs and PBDEs, are discussed. 

No degradation of PBBs by plants has been recorded. In contrast to plants, animals readily absorb PBBs [2]. Data on environmental fate (although limited to MBDE, DiBDE, DeBDE) suggest that biodegradation is not an important degradation pathway for PBDEs, but that photodegradation may play a significant role [3]. 

No matter the source, flame retardants, especially the poly brominated diphenyl ethers (PBDE s), are coming under scrutiny because they are persistent organic pollutants (POPs). They are appearing in human samples, most notably serum, adipose fat tissue and breast milk. PBDE s are also under investigation as potential endocrine mimickers or endocrine disrupters. As a result, PBDE s are the most highly regulated flame retardants. Their environmental fate will continue to be a topic of research for years to come. 

Polychlorinated Dibenzo-(p)-Dioxins and Dibenzo-Furans. Another group of compounds that we need to specifically address are the polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzo-furans (PCDFs) (Fig. 2.15). The PCDDs and PCDFs are not intentionally produced but are released into the environment from various combustion processes and as a result of their occurrence as unwanted byproducts in various chlorinated chemical formulations (e.g., chlorinated phenols, chlorinated phenoxy herbicides see Alcock and Jones, 1996). Because some of the PCDD and PCDF congeners are very toxic (e.g., 2,3,7,8-tetrachloro dibenzo-p-dioxin, see margin), there have been and still are considerable efforts to assess their sources, distribution, and fate in the environment. Similarly to the PCBs or DDT (see above), the PCDDs and PCDFs are highly hydrophobic and very persistent in the environment. It is therefore not surprising that they have also been detected everywhere on earth (Brzuzy and Hites, 1996 Lohmann and Jones, 1998 Vallack et al., 1998). Finally, we should note that polybrominated diphenylethers (PBDEs, see margin) that, like the PBBs (see above), are used as flame retardants, are of increasing environmental concern (de Boer et al., 2000). 

Semi-volatile organohalogen compounds, such as PBDEs, exist in the atmosphere in the gas-phase or associated with the particle-phase. The partitioning of compounds between these atmospheric phases is an important factor in their subsequent fate, transport, degradation, and human exposure assessment. Particle-to-gas partitioning is controlled largely by the physical properties of a compound, such as its vapor pressure and by the prevailing environmental conditions, such as the atmospheric temperature. As noted above, in the Strandberg et al. study, the samples were selected from days when the atmospheric temperature was 20 3 °C [42], At this temperature, the PBDEs were present in both the particle- and gas-phases, except for BDE-209, which was present only in the particle-phase. 

Zhang, X., Diamond, M. L., et al. (2009) Multimedia modeling of PBDE emissions and fate indoors. Environmental Science and Technology, 43(8) 2845-2850. 

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