Replacement substances for the brominated flame retardants PBDE, HBCDD, and TBBPA

A literature and database review was conducted with the aim of identifying new alternative flame retardants (FRs) used as replacement chemicals for the traditionally used polybrominated diphenylethers (PBDEs) and hexabromocyclododecane (HBCDD), and also for tetrabromobisphenol-A (TBBPA). Firstly, selected patents from the US patent database were studied and a number of alternative FRs could be identified, including, e.g., pentaerythritol, melamine, and bis-(t-butylphenyl) phenyl phosphate. Secondly, two databases, containing quantity information on usage from Sweden and the EU, were searched to obtain usage data. In Sweden, the FR that is used in the highest quantities is pentaerythritol, followed by e.g., short-chained chlorinated paraffins (SCCPs), 2-ethylhexyl diphenyl phosphate (EHDPP), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), and tetrabromobisphenol-A-bis(2,3-dibromopropyl) ether (TBBPA-BDBPE). In the EU, pentaerythritol and melamine are used in the highest quantities, followed by e.g., SCCPs, MCCPs, 1,2-bis(2,3,4,5,6-pentabromophenyl)ethane (DBDPE), and triethyl phosphate (TEP). From the Swedish database, exposure indices were obtained, indicating the potential of exposure for different environmental compartments to different FRs. The highest average potential of exposure was found for pentaerythritol, tributyl phosphate (TNBP), triphenyl phosphate (TPHP), SCCPs, and tritolyl phosphate (TMPP). In addition, time trends in the potential of exposure were obtained from the database and showed increasing trends for TBBPA-BDBPE, tris(tribromoneopentyl) phosphate (TTBNPP), DBDPE, Resorcinol bis(diphenyl phosphate) (PBDPP), TMPP, and cresyl diphenyl phosphate (CDP). Thirdly, the open literature (including international peer-reviewed articles and reports from environmental authorities), was reviewed in search for previously reported environmental concentrations of emerging FRs in indoor dust, indoor and outdoor air, water, sediment, sludge, soil, atmospheric deposition, plants and animals including humans. In total, 66 different FRs were detected in at least one of the studied matrices. In addition, six prioritization lists were identified, which included about 50 different FRs that were suggested to be of high environmental relevance. Finally, to be able to prioritize between the identified FRs for future screenings, a multicriteria model was developed based on (i) usage, (ii) time trends in the potential of exposure, (iii) environmental detection, and (iv) previous publication lists. From this multicriteria model, the top ten FRs were: TBBPA-BDBPE, DBDPE, BTBPE, TTBNPP, bis(2-ethyl-1-hexyl)tetrabromophthalate (BEH-TEBP), ethylene bis-tetrabromo phtalimide (EBTEBPI), PBDPP, para-TMPP, TPHP, and tri(1-chloro-2-propyl) phosphate (TCIPP). These FRs are suggested to be prioritized in future screenings.