69 studies were analysed , covering four alkyl OPFRs, five aryl OPFRs and fifteen chlorinated or brominated FRs. Principal metabolites of OPFRs are identified as di-alkyl phosphates (DAPs) and hydroxylated OPFRs. These are concluded to have low bioaccumulation potential but possible developmental toxicity and endocrine effects. The metabolites of the current brominated FRs are considered to have high stability in animal bodies and possible cytotoxicity, neurotoxicity, genotoxicity and hormone or endocrine effects. The authors conclude that more research is needed on the metabolism of recent FRs in different organisms and across food webs, and on effects of co-exposure to FRs and to their metabolites.
FRs considered:
– alkyl-OPFRs :tributyl phosphate (TNBP), tris(2-butoxyethyl) phosphate (TBOEP), tri(2-ethylhexyl) phosphate (TEHP), and tripropyl phosphate (TPRP)
– aryl-OPFRs [tripheny phosphate (TPHP), tricresyl phosphate (or so-called tris(methylphenyl) phosphate) (TCP or so-called TMPP), cresyl diphenyl phosphate (CDP), 2-ethylhexyl diphenyl phosphate (EHDPHP), and bisphenol A bis (diphenylphosphate) (BPA-BDP)
– halogenated FRs: TBB, tis(2-ethylhexyl)-2,3,4,5-tetrabromophtalate (TBPH), pentabromotoluene (PBT), pentabromophenol (PBP), hexabromobenzene (HBB), pentabromoethylbenzene (PBEB), 2,3,4,5-tetrabromo-6-chlorotoluene (TBCT), tribromophenol (TBP), 2,4,6-tribromophenyl allyl ether (ATE), and pentabromobenzyl acrylate (PBBA), DBDPE, BTBPE, tetrabromobisphenol A-bis(2,3-dibromopropylether) (TBBPADBPE), tetrabromoethylcyclohexane (TBECH), dechlorane plus, tris(2-chloroethyl) phosphate (TCEP), tris(2-chloroiso-propyl) phosphate (TCPP), and tris(2-chlorol-chloromethy) phosphate (TDCPP).
“The metabolism of novel flame retardants and the internal exposure and toxicity of their major metabolites in fauna – a review”, R. Hou et al., Environ Expo Assess 2023;2:10 https://dx.doi.org/10.20517/jeea.2023.08