Arlene Blum, Heather Stapleton and several other scientists from six universities in North America have published a paper comparing toxicity and exposure of organophosphorus flame retardants (OPFRs) to brominated flame retardants (BFRs). Firstly, total levels of OPFRs in water and air are compared to total PBDEs, showing to be generally higher. However, the data come from different studies so are not necessarily comparable, and it is not clear why total OPFRs are compared to levels of only one class of (organo)brominated FR. The paper does note that environmental accumulation of OPFRs is not expected, due to their lower environmental persistence. Secondly, toxicity is compared using computational modelling, for six non-halogenated OPFRs (TPHP, IPP, EHDPP, BPDP, IDDP, TMPP = all additive phosphorus esters) and two halogenated OPFRs (TDCIPP, TCEP) to two BFR classes (PBDEs and TBBPA). This shows (estimated) exposure concentrations lower than modelled effect thresholds for four of the six non-halogenated OPFRs (IPP, EHDPP, BPDP, IDDP) but possibly reaching these modelled thresholds for TPHP and TMPP. The authors conclude by proposing to move away from addition of any flame retardant chemicals to products, thus apparently drawing conclusions for all types of FRs (inorganic chemicals, mineral clays, polymers …) and for all types of organophosphorus FRs (e.g. DOPO derivatives, phosphites …) from modelling of (only four representatives) of a specific chemical family, the phosphorus esters.
Adrian Beard, chairman of pinfa, comments: “pinfa does not consider it valid to treat all phosphate esters as one group, because some of these chemicals are already under regulatory scrutiny or have been restricted (e.g. chlorinated alkyl phosphates TCEP and TCPP), whereas others have data showing their good environmental and health profiles. Nevertheless, pinfa welcomes critical research. We are currently discussing this paper in depth with our experts, both the methodology and the results, and we are open for dialogue with the authors, other scientists and stakeholders.”
TPHP = triphenyl phosphate, IPP = isopropylated phenyl phosphate, EHDPP = 2-ethylhexyl diphenyl phosphate, BPDP = tert-butylated phenyl diphenyl phosphate, IDDP = isodecyl diphenyl phosphate, TMPP = trimethyl phenyl phosphate). TDCIPP = tris(1,3-dichloro-2-propyl) phosphate, TCEP = tris(2-chloroethyl) phosphate.
“Organophosphate Ester Flame Retardants: Are They a Regrettable Substitution for Polybrominated Diphenyl Ethers?”, A. Blum, H. Stapleton et al., Environ. Sci. Technol. Lett. 2019 http://dx.doi.org/10.1021/acs.estlett.9b00582