Thresholds in respiratory sensitisation

Task Force Manager Alan Poole

Administrative Assistant Christine Yannakas


Respiratory sensitisation gains increasing importance in EU regulations as an endpoint driving restrictive measures. The Biocidal Product Regulation suggests respiratory sensitisers for substitution. Under REACH, several substance classes are under discussion for inclusion into Annex XIV (Authorisation list) as Substances of Very High Concern (SVHCs) based on their classification as respiratory sensitisers. Substance properties qualifying according to REACH Art 57 for “equivalent concern‘ are “scientific evidence of probable serious effects to human health which give rise to an equivalent concern“ comparable to CMR1A/1B substances. The reasoning by some stakeholders to subject respiratory sensitisers to authorisation under REACH is that:

  • Occupational asthma is a serious, irreversible disease;
  • At the present time, it is not possible to define reliable dose-response relationships and thresholds for most respiratory sensitisers.

A broad scientific review on available evidence on thresholds in respiratory sensitisation would support discussions by risk assessors and risk managers on how to assess and regulate respiratory sensitisers.

Terms of reference

  1. Based on a review of the relevant literature, summarise the current knowledge on mode of actions, including potential differences between small molecules/‘chemicals‘ and macromolecules
  2. Elaborate the coherence of findings in animal models versus humans
  3. Describe knowledge on thresholds in induction versus elicitation of respiratory sensitisation
  4. Conclude on whether respiratory sensitisation can be regarded to be a threshold effect with reasonable certainty, and recommend appropriate experimental models or other approaches to derive safe concentrations
  5. Compare the type of possible effects by respiratory sensitisers to those of CMR1A/1B substances

The task force will write a technical report and a publication for the peer-reviewed literature. The draft report should be available within one year from the start of the task force. A workshop to discuss the outcome with a wider audience may be proposed and, possibly, a suitable networking within industry and beyond.

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