Novel flame retardants: Estimating the physical-chemical properties and environmental fate of 94 halogenated and organophosphate PBDE replacements

In the wake of the listing by the Stockholm Convention of PBDEs, an increasing number of "novel" flame retardants (NFRs) are being used in products. The properties that make for desirable flame retardants can also lead to negative health effects, long environmental residence times and an affinity for organic matrices. While NFRs are currently in use, little information is available regarding their physical-chemical properties and environmental fate. In this study, 94 halogenated and organophosphate NFRs were evaluated for their persistence and long-range transport potential. Physical-chemical properties (namely liquid sub-cooled vapor pressure P_l and solubility S_l, air-water (K_AW), octanol-water (K_OW), and octanol-air (K_OA) partition coefficients) of the NFRs were predicted using three chemical property estimation tools: EPI Suite, SPARC and Absolv. Physical-chemical properties predicted using these tools were generally within 10²-10³ for compounds with molecular weight < 800 g/mol. Estimated physical-chemical properties of compounds with >800 g/mol, and/or the presence of a heteroatom and/or a polar functional group could deviate by up to 10¹². According to the OECD P_OV and LRTP Screening Tool, up to 40% of the NFRs have a persistence and/or long range transport potential of medium to high level of concern and up to 60% have persistence and or long range transport potential similar to the PBDEs they are replacing. Long range transport potential could be underestimated by the OECD model since the model under-predicts long range transport potential of some organophosphate compounds.