Workplace irritant exposures: do they produce true occupational asthma?

The recognition that irritant exposures can cause asthma is not new. Many investigators turn towards the gassings of soldiers in World War I as the first examples of this, while Brooks, in 1985, reported this in detail in workers and called it 'Reactive Airways Dysfunction Syndrome (RADS)'. There is considerable overlap with RADS and occupational asthma as both share respiratory symptoms which can be described as 'asthmatic', yet RADS is the result of an acute excessive exposure, while occupational asthma occurs due to a series of sensitizing exposures. Yet, a clear understanding of RADS has been limited by the lack of epidemiologic studies; rather the disease has been described by case series. This report contrasts RADS and occupational asthma and finds that although there may be some difference in lung pathology, reports for the past years since Brooks' initial reports have shown that the line separating occupational asthma and RADS has become increasingly blurred, rather than increasingly distinct, with considerable overlap in the clinical symptoms with the perspective that these described entities are a part of a continuum. Perhaps the development of animal models for RADS may hasten further understanding.