To the Editors:Substantial evidence exists that indoor dust contains poly-brominated diphenyl ethers (PBDEs), which are structurallysimilar to the known human toxicants PBBs, PCBs, dioxins,and furans. In addition to having similar mechanisms oftoxicity in animal studies, they also bioaccumulate andpersist in both humans and animals (Blum 2007). Duringthe past decades, PBDEs have been produced in largeamount and universally used in indoor environment.Though pentabromodiphenyl ether (Penta-BDE) and octab-romodiphenyl ether (Octa-BDE) commercial mixtures havebeen added to the POPs list of the Stockholm Conventionand have been banned in some regions for their persistenceand toxicity, decabromodiphenyl ether (Deca-BDE) is stillproduced and applied around the world, with China includ-ed, which means that it is possible that the proportion ofDeca-BDE in indoor environment and in indoor dust wouldrise in the future. In 2001, the last year for which figures areavailable, global production of Deca-BDE, Octa-BDE, andPenta-BDE amounted to 56,100, 3,790, and 7,500 t(83:6:11 %), respectively (Hazrati et al. 2010). Used as fireretardants, they will migrate from indoor consumergoods andwill be exposed to human beings in a longer future time.Indoor dust is a complex mixture of particulate materialsof both natural and anthropogenic origin. Like all semi-volatile substances (SVOCs), PBDEs are present in both,indoor air and indoor dusts, often primarily in the latter,depending on the vapor pressures of the compounds. Thus,indoor dust acts as a sink for SVOCs including PBDEs. AsDeca-BDE has the lowest volatility but the largest applica-tion amount (83 % of all PBDEs), the major proportion ofPBDEs in indoor environment will occur in indoor dust. Inrecent years, study on PBDEs has been focused on indoordust because PBDEs, especially Deca-BDE in indoor dust,are the major threat to human health compared with that ingas phase and other matrix. The analysis of organic com-pounds adsorbed on indoor dust has been recognized as avaluable tool for estimating indoor pollution, and indoordust is proposed as anindicatorof residential contamination.Seen as “indoor POPs,” PBDE levels in the indoor envi-ronment are much higher than those in the outdoors asshown by numerous studies all over the world. The medianPBDE concentrations in home dust range from some lowlevels found in Thailand (10 ngg