Polybrominated+diphenyl+ethers


 * Polybrominated diphenyl ethers ** or ** PBDEs **, are [|organobromine compounds] that are used as [|flame retardants] . Like other [|brominated flame retardants] , PBDEs have been used in a wide array of products, including building materials, electronics, furnishings, motor vehicles, airplanes, plastics, [|polyurethane] foams, and textiles. They are structurally akin to the [|PCBs] and other [|polyhalogenated compounds] , consisting of two [|halogenated] aromatic rings. PBDEs are classified according to the average number of [|bromine] atoms in the molecule. The health hazards of these chemicals have attracted increasing scrutiny, and they have been shown to reduce fertility in humans at levels found in households. [|[1]]  Their chlorine analogs are [|polychlorinated diphenyl ethers] (PCDEs). Because of their toxicity and persistence, their industrial production is to be eliminated under the [|Stockholm Convention] , a treaty to control and phase out major [|persistent organic pollutants] (POPs).

The family of PBDEs consists of 209 possible substances, which are called [|congeners] (PBDE = C12H(10−x)BrxO (x = 1, 2, ..., 10 = m + n)). The number of isomers for mono-, di-, tri-, tetra-, [|penta-], hexa-, hepta-, [|octa-] , nona-, and [|decabromodiphenyl ethers] are 3, 12, 24, 42, 46, 42, 24, 12, 3 and 1, respectively [|[2]]. In the United States, PBDEs are marketed with trade names: DE-60F, DE-61, DE-62, and DE-71 applied to pentaBDE mixtures; DE-79 applied to octaBDE mixtures; DE 83R and Saytex 102E applied to decaBDE mixtures. The available commercial PBDE products are not single compounds or even single congeners but rather a mixture of congeners.

Lower brominated PBDEs
These species average 1-5 [|bromine] atoms per molecule and are regarded as more dangerous because they more efficiently [|bioaccumulate]. Lower-brominated PBDEs have been known to affect [|hormone] levels in the [|thyroid] gland. Studies have linked them to reproductive and neurological risks at certain concentrations or higher. [|[3]]

Higher brominated PBDEs
These species average more than 5 [|bromine] atoms per molecule.

The commercial mixture, named pentabromodiphenyl ether, contains the pentabromo derivative predominantly (50-62%), however the mixture also contains tetrabromides (24-38%) and hexabromides (4-8%), as well as traces of the tribromides (0-1%). In similar manner, commercial octabromodiphenyl ether is a mixture of homologs: hexa-, hepta-, octa-, nona-, and decabromides.