The document discusses grouping of chemical substances and the issue of regrettable substitution. It notes that grouping enables extrapolation of hazard properties from data-rich to data-poor substances and can help address the data deficit problem. However, there is a risk of regrettable substitution, where an unsafe substance is replaced by another unsafe substance. The document then provides an example of an expert committee recommending grouping to some extent for the assessment of organohalogen flame retardants into 16 groups, as individual assessments of each chemical would be unrealistic. It raises questions about ensuring consistent global approaches to grouping while addressing legislative and chemical diversity, and how risk assessors should define groups.

1. © Copyright 2019 Chemical Watch (CW Research Ltd)
Grouping of chemical
substances and
regrettable substitution
Chair: Andrew Turley, Science
Editor, Chemical Watch

2. © Copyright 2019 Chemical Watch (CW Research Ltd)
Panelists
Ninja Reineke, Chemtrust
Jack de Bruijn, ECHA
Maggie Saykali, Cefic
Kerry Nugent, IMAP, NICNAS

3. © Copyright 2019 Chemical Watch (CW Research Ltd)
Grouping
● For overcoming the data deficit problem
● Enables extrapolation of hazard properties from a data-rich
substance to a data-poor substance that is ‘similar’ (read-across)
● When an unsafe substance is substituted for...another
unsafe substance
Regrettable substitution

4. A recent example
● Request made by regulatory authority
● Independent expert committee recommends
grouping (to some extent…) for assessment of
organohalogen flame retardants
● 16 groups
● “The alternative – individual assessments of
hundreds of chemicals – is unrealistic"

5. Opening questions
● Is everyone using the same approaches to grouping?
○ Minimise duplication of work globally; provide greater certainty for industry; but
○ Challenging given diversity of legislative constraints and diversity of chemicals
● In each case, should the approach be:
○ General (IE, agnostic with respect to chemical structure, use, exposure route, etc);
○ Tailored to the chemicals under consideration; or
○ Something in between?
● How should risk assessors define groups?