Peter Fisk, Green Chemical Design presented a study underway for pinfa, looking at whether organo-phosphorus flame retardants (OPFRs) is a meaningful group of chemicals for generic legislation, or how they could be appropriately grouped. He underlined that the REACH dossiers for OPFRs are data rich: studies are available for most required end-points and read-across is little used. Analysis of the REACH data shows that grouping of all PIN OPFRs is very inappropriate, because they show highly variable chemical properties and very different toxicity effects. Ecotoxicity is largely related to KOW (octanol-water partition coefficient, indicative of whether the chemical tends to be water or lipid soluble). Assessment showed that Hansen Solubility Paraments (HSP) for dispersion and polarity varied widely between OPFRs, and that 6 ‘clusters’ of different OPFRs could be identified by these parameters. This possible grouping generally seemed to correspond to ecotox and tox properties, except for the trialyklphosphate esters where only one substance shows carcinogenicity. Therefore, it is necessary to check whether to exempt certain products or subdivide structural groups further before considering regulatory measures on a (sub-)group.