Ah Receptor Agonists in UV-exposed Toluene Solutions of Decabromodiphenyl Ether (decaBDE) and in Soils Contaminated with Polybrominated Diphenyl Ethers (PBDEs) (9 pp) (original) (raw)
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Polybrominated diphenyl ethers (PBDEs) are important chemical flame retardants, but also environmental pollutants. Their behaviour in the environment is a function of their inherent molecular properties, largely governed by the number and character of the bromine atoms substituted, and the microenvironment where they reside. In this thesis different aspects of importance for the understanding of the behaviour of lower brominated and higher brominated PBDEs in the environment are addressed. The contamination of a Swedish freshwater system with lower brominated BDEs was assessed by a retrospective study of pike from Lake Bolmen covering the time period 1967 to 2000. The concentrations of tetra-to hexaBDEs increased exponentially up to the mid-1980s and then leveled off/decreased slowly, possibly reflecting the voluntary reduction in production and usage of lower brominated BDEs in Europe. Methoxylated PBDEs were found to be present in similar concentrations to the PBDEs. However, there was no correlation between the levels of the two substance groups, and it was therefore concluded that they originated from different sources. To understand the low abundance of higher brominated BDEs in wildlife despite their extensive use and high levels in e.g. sediment, the dietary uptake of the fully brominated BDE, BDE209, was studied in fish. Although it was not expected to be taken up due to its large size and hydrophobicity, it was absorbed to a small extent via the diet. Once absorbed, BDE209 was reductively debrominated to nona-to hexa-brominated BDE congeners. Reductive debromination in vivo was also demonstrated in dairy cows exposed to higher brominated BDEs in their natural diet. The transfer of BDE209 to milk was low (< 0.2 %). In contrast to PCBs and lower brominated BDEs, there was no equilibrium between adipose tissues and milk fat, and for congeners with a log K ow > 7 a progressively smaller fraction of the ingested PBDEs was transferred to the milk. The results indicate that while lower brominated BDEs are excreted in the milk of dairy cows exposed to PBDEs, the higher brominated BDEs are accumulated in the meat. At the same time that PBDEs were receiving increasing regulatory attention, the next generation of brominated flame retardants was introduced. In this thesis decabromodiphenyl ethane, a replacement for the technical BDE209 formulation, was identified for the first time in the environment. This thesis identified differences in uptake, metabolism and excretion for brominated compounds compared to the previously thoroughly characterized organochlorines. This knowledge will be useful for future risk assessments given the ongoing use of these brominated aromatic compounds. "To dare is to lose one's footing momentarily. Not to dare is to lose oneself." Sören Kierkegaard v List of papers This thesis is based upon the following papers which are referred to in the text by their Roman numerals. I Polybrominated diphenyl ethers (PBDEs) and their methoxylated derivatives in fish from Swedish waters with emphasis on temporal trends, 1967-2000.
Environmental Science & Technology, 2009
The potential photochemical formation of polybrominated and mixed halogenated dibenzo-p-dioxins (PBDDs and PXDDs) from hydroxylated polybrominated and polybrominated/ chlorinated diphenyl ethers (OH-PBDEs and OH-PBCDEs) in aqueous solution was studied. The ortho-hydroxylated BDE47 derivative 6-OH-BDE47, and chlorinated derivatives 3-Cl-6-OH-BDE47, 5-Cl-6-OH-BDE47, and 3,5-Cl-6-OH-BDE47 were photolyzed under sunlight at 45 degrees N latitude in buffered waters, Mississippi River water, Lake Josephine water, and ultrapure water adjusted to the pH of the natural waters. Chemical actinometry was used to determine reactant quantum yields which were calculated to be between 0.03 and 0.21, with lower yields for the chlorinated derivatives under all conditions. Quantum yields under natural water conditions were not significantly enhanced indicating that direct photolysis is the primary process of photochemical degradation. The formation of halogenated dioxins from the outdoor photolysis of the four OH-PBDEs/OH-PBCDEs under all conditions was confirmed. Dioxin yields of 0.7-3.6% were found, with higher yields for 6-OH-BDE47 under all conditions. This study suggests that photolysis of OH-PBDEs and OH-PBCDEs is a potential formation pathway of PBDDs and PXDDs in the environment.
Polybrominated diphenyl ether fl ame retardants in the U.S. marine environment: A review ⁎
Lichens and mosses are considered good indicators of atmospheric pollution as they absorb contaminants directly from the air. Polybrominated diphenyl ethers (PBDEs) are man-made chemicals used as flame retardants in materials such as plastics, textiles, electronic circuitry and furnishing foam. Few studies have investigated PBDEs in the southern hemisphere including Antarctica. This paper presents the first evaluation of PBDEs in lichens (Usnea antarctica and Usnea aurantiaco-atra) and mosses (Sanionia uncinata) collected at King George Island, maritime Antarctica. PBDEs were detected at low levels in all lichen and moss samples. On average, the levels of PBDEs in mosses (818 pg g À1 dry weight; 101 ng g À1 lipid) were significantly higher than in lichens (168 pg g À1 dry weight; 9.11 ng g À1 lipid). This difference is most likely due to the differing mechanisms of PBDEs uptake from the atmosphere which are controlled by a number of chemical, environmental and plant variables. Contaminant concentrations were not statistically different at sites close to and distant from human facilities. Long-range atmospheric transport is believed to be the primary source of PBDEs to King George Island. The pattern of congeners in plants resembles those found in commercial mixtures of Penta-BDE. In addition, the presence of BDE-183 in lichens and mosses suggests that other technical formulations (e.g., Octa-BDE and Deca-BDE) have reached Antarctica. Further studies are needed to better understand the role of Antarctic vegetation as a sink for anthropogenic organic pollutants.
Environmental analysis of higher brominated diphenyl ethers and decabromodiphenyl ethane
Journal of Chromatography a, 2009
Methods for environmental analysis of higher brominated diphenyl ethers (PBDEs), in particular decabromodiphenyl ether (BDE209), and the recently discovered environmental contaminant decabromodiphenyl ethane (deBDethane) are reviewed. The extensive literature on analysis of BDE209 has identified several critical issues, including contamination of the sample, degradation of the analyte during sample preparation and GC analysis, and the selection of appropriate detection methods and surrogate standards. The limited experience with the analysis of deBDethane suggests that there are many commonalities with BDE209. The experience garnered from the analysis of BDE209 over the last 15 years will greatly facilitate progress in the analysis of deBDethane.