Abstract

A retrospective review was performed on the files of 154 consecutive workers assessed for occupational asthma to clarify the relative frequency of asthma induced by irritants in the workplace and to determine whether such asthma was clearly distinguishable from other forms of occupational asthma. Fifty-nine workers were considered to have occupational asthma. A subset of ten had a history consistent with asthma initiated by exposure to high concentrations of an irritant, had persistent symptoms for an average of five years when seen, demonstrated increased reactivity to methacholine, and gave no prior history of pulmonary complaints. These ten had a lower incidence of atopy (20 percent vs 58 percent) and a more frequent history of smoking (80 percent vs 38 percent) than the other subjects with occupational asthma but did not differ in average latency (5.9 years vs 5.7 years). Our findings suggest that irritant-induced asthma is not uncommon, and those affected may have different baseline characteristics from others with occupational asthma.

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Comments

A four-fold change in methacholine Pc20 was seen in 16/49 with sensitizer-induced occupational asthma (clinical diagnosis, some with challenges). 19/49 had supporting PEF changes (denominator of those actually doing the test not stated) Irritant induced asthma seen in 15, (No prior asthma, onset within 24 hours of a high exposure to a respiratory irritant on one or more occasions,symptoms persisting for at least 3 months, bronchodilator response or NSBR,) 3/15 had more than 6 months latency to similar exposures, 2/3 had NSBR work-related changes. These 3 probably had work-related pef and symptom changes ( welder,calcium oxide,phisgene/HCl).

5/18/2011