Classes of PBDEs
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. In the United States, PBDEs are marketed with the trade names DE-60F, DE-61, DE-62, and DE-71 applied to pentaBDE mixtures, DE-79 applied to octaBDE mixtures, and DE 83R and Saytex 102E applied to decaBDE mixtures. The available commercial PBDE products are not single compounds or even single congeners but rather mixtures of congeners.
Health and environmental concerns
Since the 1990s, environmental concerns were raised because of the high hydrophobicity of PBDEs and their high resistance to degradation processes. While biodegradation is not considered the main pathway for PBDEs, the photolysis and pyrolysis can be of interest in studies of transformation of PBDEs. People are exposed to low levels of PBDEs through ingestion of food and by inhalation. PBDEs bioaccumulate in blood, breast milk, and fat tissues. Personnel associated with the manufacture of PBDE-containing products are exposed to highest levels of PBDEs. Bioaccumulation is of particular concern in such instances, especially for personnel in recycling and repair plants working on PBDE-containing products. People are also exposed to these chemicals in their domestic environment because of their prevalence in common household items. Studies in Canada have found significant concentrations of PBDEs in common foods such as salmon, ground beef, butter, and cheese. PBDEs have also been found at high levels in indoor dust, sewage sludge, and effluents from wastewater treatment plants. Increasing PBDE levels have been detected in the blood of marine mammals such as harbor seals.
There is also growing concern that PBDEs share the environmental long life and bioaccumulation properties of polychlorinated dibenzodioxins.
Children whose mothers were exposed to PBDEs during pregnancy may have a lower IQ than their peers who did not experience prenatal exposure, a new study reports. Researchers found that every 10 fold increase of maternal PBDE levels was associated with a drop of 3.7 IQ points in her child.