ECHA read-across assessment framework – ‘RAAF’
June 2nd, 2015
The European Chemicals Agency (ECHA) has, after several years consultation with industry, published a document describing the approaches it uses for the assessment of read-across in human health toxicology for REACH. The document is available here.
The document is unusual because it gives detailed insight into ECHA’s methodology, and because reading across human health toxicity data is a highly sensitive area.
The sensitivity of read across for human health toxicity data arises because it involves data generated from mammals. Industry has sought to use read-across of toxicology studies to reduce the use of vertebrates in testing. NGOs also want to reduce testing, but are concerned about inadequate testing. There have been legal challenges to the rejection of read-across proposals. As a result, ECHA is evidently trying to ensure that REACH is enforced fairly in this context, as allowed for in Annex XI of the Regulation.
So what does it say? The ECHA document is not new guidance, rather it is an explanation of parts of the existing R.6 guidance document on grouping, focusing on the quality of documentation. In a rather lengthy way (given there is an annex for each case), six scenarios are described, based on whether
– analogue or category grouping of structures is used;
– biotransformation of the substance to another form is likely;
– trends are within a category or not.
ECHA clearly states that the concept of an ‘analogue group’ (as defined in the R.6 guidance) consists of a ‘very few’ substances.
The key messages are not easy to find in this long text, however, it reinforces strongly that registrants must clearly explain and validate the scientific basis of read-across; ECHA should not be expected to fill in gaps in argumentation.