PBDE
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PBDE, or polybrominated diphenyl ether is a flame-retardant of the brominated flame-retardant group rated as a Persistent Organic Pollutant. It has been used in a wide array of household products, including fabrics, furniture, and electronics. There are three main types, referred to as penta, octa and deca for the number of bromine atoms in the molecule. Of the three, deca is most commonly used and is considered the "safest" of the three. After studies in Sweden found the chemicals accumulating in breast milk and other tissues, Sweden banned the chemicals. The European Union is in the process of banning PBDEs with a full ban to be in place by 2006. Surprisingly, an experiment done the at Woods Hole Oceanographic Institution in Massachusetts in 2005 showed that the isotopic signature of PBDEs found in whale blubber contained carbon-14, the naturally occurring radioactive isotope of carbon. If the PBDEs in the whale had come from artificial (human-made) sources, they would have only contained carbon-12 and no carbon-14 due to the fact that virtually all PBDEs which are produced artificially use petroleum as the source of carbon, all carbon-14 would have long since completely decayed from that source. The experiment thus shows that there must be some as yet unidentified natural source of PBDEs.
Sub-groups
There are two sub-groups:
Low-rated PBDEs have 1-5 bromine atoms and are regarded as the most dangerous ones, because of the smaller molecules which can be absorbed by living organisms. Low-rated 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.
High-rated PBDEs have more than 5 bromine atoms and were formerly regarded as environmentally harmless chemical compounds, but studies by the Swedish Environmental Board have linked them to thin egg shells for Peregrine falcons.
Health concerns
Since 1998, there have been concerns raised about the safety of PBDEs after Swedish scientists noticed the chemicals to be accumulating in human breast milk. Based on the precautionary principle, Sweden banned PBDEs.
Some studies in Canada have found notable concentrations of PBDEs in common food products such as salmon, ground beef, butter, and cheese [1]. In Canada there is no set limit for what upper amount of PBDEs in the human body is still considered to be safe, but there remains concern in the general public that the PBDEs are having harmful effects on human health and the environment.
Environmental organizations argue that all PBDEs should be banned as they aren’t needed and replacements are available. But, the electronics industry claims that PBDEs are applied to most newly manufactured electronic assemblies such as printed circuit boards and capacitors and thus are vital to their business.
There is growing evidence that indicates these chemicals may cause liver toxicity, thyroid toxicity, and neurodevelopmental toxicity. PBDEs have also had a strong resemblance to PCBs, which, due to health concerns, were banned in the US in the late 1970s.