In recent months Peter Fisk has had the opportunity to present recent work on organophosphorus flame retardants (FRs) in two public webinars, demonstrating some novel technical approaches to the important hot topic of the grouping of substances for regulatory scrutiny.

In both presentations, over 20 phosphate ester and phosphonate ester substances used as FRs or functional fluids were considered. Some of these substances have hazard classifications.

Physicochemical, environmental and toxicological data were considered alongside the chemical structures. It was discovered that Hansen Solubility Parameters were useful molecular descriptors which divided the substances into several distinct groups. The properties of the substances were highly homogeneous in each group. The toxicological conclusions were based on in vivo studies; some published in vitro data were examined also. The in vitro results from different publications were not consistent so were not used further. It was evident from all the properties examined that the FRs could not be grouped into one set, on the basis of the structural and property data.

The first presentation was for pinfa, the Phosphorus, Inorganic and Nitrogen Flame retardants Association on June 28^th 2022. Pinfa, who supported the study, is a group of global flame retardant manufacturers and users committed to fire safety and improving the health and environmental profiles of its members products. A sector group of Cefic, the European Chemical Industry Association, pinfa was created in 2009. www.pinfa.eu

The presentation was titled One for all and all for one? To what extent can phosphorus-based flame retardants be treated as groups?

Similar material was presented in a more application-oriented event:

One-Size-Fits-All Policies: Why Different Products Call For Different Chemical Compounds
Hosted by the American Chemistry Council, on September 7, 2022

The presentation was titled Why different products require different compounds; Current EU regulatory context for Phosphorus-containing FRs

Why is such work important? The reasons are that conclusions should be based on science, and crude grouping could actually remove useful and low-hazard areas of chemistry from being applied to products.

EU regulation is in principle lead by science then secondarily by socio-economic matters.

The hierarchy of EU regulatory activity can be seen as follows:

Green Deal >
   Chemicals Strategy for Sustainability >
      Restrictions Roadmap >
         Grouping as a means to speed decision-making compared to one substance at a time

See (for example) Commission Staff Working Document, April 2022