Category approaches, read-across, (Q)SAR

Health Sciences Manager Christa Hennes

Administrative Assistant Christine Yannakas

The task force completed its work in 2012; the Technical Report No. 116 can be downloaded here.

Categorisation, read-across and (quantitative) structure-activity relationships are alternative approaches to fill data gaps, for example, in chemical safety dossiers for REACH. They are, in principle, accepted by regulatory authorities but difficulties remain in practice. Technical guidance is available and there are a plethora of models and tools. Guidance, however, on applying them in practice is still missing. This Task Force had the objective of summarising guidance and tools available, reviewing their practical utility and providing recommendations and learning. A number of case studies were added for illustration.

This ECETOC report was developed within a few months only, thanks to the hard work by the Task Force members. It was shared in time with the participants of a workshop by ECHA (with the active support from Cefic-LRI) on “Read-across assessment‘ held last October.


An accepted practice for the assessment of human health and environmental safety of chemicals is the use of models and analogues to fill data gaps for specific endpoints either for single or multiple chemicals that share structural similarities, and/or comparable reactivity or similarities in metabolism in mammals, fish and other organisms. For example, this approach is acceptable, with limitations, in preparing dossiers for REACH, and it supports efforts for reducing animal testing. The OECD has published guidance on the formation and use of chemical categories for data gap filling. An ECETOC Task Force recently produced TR 109: High information content technologies in support of read-across in chemical risk assessment; a project that has highlighted methods for read-across.

With the plethora of models and guidance growing for both human health and the environment, it would be prudent to identify recommended practices. Additionally, the 2013 and 2018 REACH deadlines are pending; these deadlines require lower volume producers and importers to submit chemical safety assessments. A report describing recommended practices in this area would be useful in supporting industry‘s risk characterisation and prioritisation activities across all sectors.

It is recommended that a Task Force of industry and regulatory experts on categorisation methods, read-across and the use of (Q)SAR in risk assessment prepares such a report. This should be published as a relatively brief ECETOC “special report‘ and be available by summer 2012.

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