Accurate regulatory classification of chemical respiratory allergens: The case for robust characterisation of...

Occupational health standards, worker safety and effective regulatory classification relies upon characterisation of occupational asthma and discrimination between allergic asthma, irritant-induced asthma, and work-exacerbated asthma, and the accurate identification of chemical allergens of the respiratory tract. No in silico, in vitro or in vivo experimental method can, either alone or in combination, accurately identify chemical respiratory allergens and provide a sound basis for regulatory classification. Measurement of IgE antibody and skin prick testing can characterise allergy to proteins, but not to chemical respiratory allergens. Therefore, characterisation of causation and accurate regulatory classification of work-related asthma relies upon characterisation of clinical and workplace histories and specific inhalation challenge tests conforming to current guidelines and best practice. This manuscript reviews the important of accurate characterisation of causation in cases of work-related asthma to ensure accurate classification and robust regulation, and to promote a sound basis for clinical and experimental research. Commentaries on selected clinical case studies are provided that highlight key issues that confound attribution of causation. Specific recommendations are made regarding the design, conduct and interpretation of clinical investigations of work-related asthma that could provide a basis of more robust regulatory practice, and the more reliable identification of chemical respiratory allergens.