Asthma in apprentice workers The birth cohort parallel: Using apprentices as a powerful cohort design for studying occupational asthma

Abstract

This chapter presents a review of longitudinal studies of apprentices in trades and professions entailing substantial risks for the development of occupational asthma (OA). Prospective studies of OA enable the assessment of host characteristics before apprentices/workers enter a particular workforce, thus before being exposed to a suspected etiological agent, as well as the early detection of sensitization to a specific work-related antigen and the evaluation of bronchial responsiveness before onset of symptoms of asthma. Since 1973, several cohort studies have been conducted in Europe and Canada among apprentices exposed to high- and low-molecular-weight agents. The investigated outcomes were, apart from OA, work-aggravated asthma, bronchial hyperresponsiveness, work-related symptoms and specific sensitization. The rate of onset of the relevant outcomes was high even after 1 year of training; the implications for setting timing of surveillance programs would be to screen for sensitization and symptoms in the first 2-3 years of apprenticeship. Several host factors assessed at baseline were identified as risk factors for the incidence of work-related outcomes. However, more investigations are needed to explore the extent to which the risk of work-related allergy and asthma increases with exposure characteristics during apprenticeship. Directions for research in the existing cohorts and in future ones are suggested.