Occupational asthma: dust exposure as a contributory factor and implications for classification of respiratory...

Occupational asthma (AO) is an important chronic respiratory disease associated with airway narrowing. Chemicals that cause OA are regulated under the UN GHS endpoint of respiratory sensitisation. Such chemicals are typically identified using evidence suggesting work-related exposure resulting in the ab initio development of asthma, rather than simply aggravating pre-existing asthma (work exacerbated asthma; WEA). There exist predisposing and aggravating factors within and outside the workplace that influence the development and severity of the disease. Inhalation exposure to dusts is one factor and is recognised as directly causing respiratory disease, and also aggravating pre-existing disease, including asthma. Here the contribution of dusts to the development of work-related asthma has been re-examined with reference to published clinical case studies. The data reveal a link between exposure to dusts and OA, suggesting an additional role of dust in this respect may be the presentation of irritant or sensitising agents in a way that promotes the development of OA, even under conditions where exposure to those agents alone does not. We propose that the significance of co-exposure to dusts may be currently under-estimated in health management of OA, clinical identification of chemicals suspected of causing OA, and classification of true respiratory sensitisers.