In a nutshell: Chemical respiratory allergy – clinical information and how to use it and improve it

Brussels, March 2017

A variety of natural and man-made materials can cause allergic sensitisation of the respiratory tract in susceptible individuals. However, the mechanisms involved in the development of chemical respiratory allergy1 are currently not fully understood and no validated models exist for the identification of chemical respiratory allergens. There are also no methods suitable for the routine assessment of threshold values for sensitisation (the first stage in the development of allergy) of the respiratory tract by chemicals and thus human exposure thresholds are poorly characterised. All this creates great uncertainty surrounding the identification and safe-use of H334 (previously assigned the risk phrase R42) classified substances.

A workshop was therefore held with the two main aims of:

  1. Developing best practice guidance on how to assess and use available human data for the identification of chemical respiratory sensitisers
  2. Driving discussions on identifying human biomarkers for chemical respiratory sensitisation and the use of such tests to identify more accurate human threshold data, which would help refine current risk assessment approaches for the use of such materials, both from occupational and consumer exposure standpoints.

The workshop identified various areas that could drive improvements in the identification, classification and risk characterisation of chemical respiratory sensitisers and recommended several practical steps to improve the current situation, which are captured in the workshop report.

This report will be of interest to academic researchers, occupational health clinicians, industrial toxicologists and regulatory bodies involved in the identification, characterisation, risk assessment and risk management of chemical sensitisers.

1 For the workshop, chemical respiratory allergy was defined as an immune-mediated hypersensitivity reaction to an exogenous low molecular weight chemical resulting in symptoms such as asthma and rhinitis.

A synopsis of the meeting is found in ECETOC Workshop Report no.33: Chemical Respiratory Allergy: Clinical Information and How To Use It and Improve It. October 27-28 October 2016, Madrid.

The Executive Summary and free PDF of the report are available at