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BROMINATED FLAME RETARDANTS: WHY DO WE CARE?
Citation:
KODAVANTI, PRASADA RAO S. BROMINATED FLAME RETARDANTS: WHY DO WE CARE? Presented at Building an Integrated Surveillance System for Emerging Chemicals in Great Lakes and Nationwide, Chicago, IL, July 16 - 18, 2007.
Description:
Brominated flame retardants (BFRs) save lives and property by preventing the spread of fires or delaying the time of flashover, enhancing the time people have to escape. The worldwide production of BFRs exceeded 200,000 metric tons in 2003 placing them in the high production volume chemical (HPV) category. The major BFRs include tetrabromobisphenol A (TBBPA), hexabromocyclododecone (HBCD), and polybrominated diphenyl ethers (PBDEs). These compounds have been used in electronics/circuit boards, textiles, thermal insulation, plastics, and foam material. Due to their widespread use and high persistence in the environment, BFRs have become a ubiquitous environmental contaminant similar to polychlorinated biphenyls (PCBs) and have been detected in all tested biological samples. Although the main route of exposure to most of the persistent chemicals is through ingestion of food, inhalation of dust seems to play a major role for PBDEs. Human health concerns stem from the fact that some of the BFRs are structurally similar to PCBs which are known to adversely affect human health. There are 209 PBDE congeners based on position and number of halogens similar to PCBs. In addition, levels of PBDEs have been increasing in almost all the environmental and biological samples. Although there are no epidemiological studies on human health effects, the effects on mammals and aquatic species include developmental delay, endocrine disruption, hepatic-, neurological-, reproductive-, and immune system alterations. Since there is not sufficient pharmacokinetic data on this group of chemicals for extrapolation from rodents to humans with confidence, one approach for risk assessment could be to compare current levels of PBDEs in humans with the levels of PCBs that are known to produce adverse human health effects including developmental neurotoxicity which is considered to be one of the most sensitive endpoints. Studies from Netherlands and Germany documented adverse effects associated with cognition when breast milk levels of ortho-substituted non-coplanar PCBs were in the range of 263-1615 ng/g (median = 690 ng/g). In North America, PBDEs in breast milk were reported to be in the range of 6-1078 ng/g with a median of 34-58 ng/g, which is ten times less than those of PCBs. However, the top 5% of population have levels similar to PCBs and this may pose a risk. Since the effects of PCBs and PBDEs are mostly additive and some times synergistic, the levels of PBDEs at current level may be producing adverse health effects. Additional research is needed to better assess the risk associated with exposure to these persistent chemicals. (This abstract does not necessarily reflect USEPA policy).