RESUMO
Pulmonary flow rates and methacholine inhalation challenge were assessed in 150 Egyptian male petroleum workers and 50 male normal control subjects to study the effect of exposure to pollutants in petroleum industry on airways. According to methacholine inhalation challenge [MIC] the workers were distinguished into positive [PW+, n=27] and negative [PW-, n=123] responders. The positive response is 20% or more fall in FEV1. In the [PW+] pulmonary flow and MIC assessment were repeated after three months away from exposure. The pulmonary flow rates of the [PW+] and [PW-] were similar and significantly lower than those of normal subjects. The slope and intercept of the methacholine dose-response curves of [PW+] and [PW-] were significantly different from those of the normal subjects indicating bronchial hyperreactivity and hypersensitivity in petroleum workers whether positive or negative methacholine responders. Three months away from exposure in [PW+] resulted in significant changes of the intercept without changes of the slope of the curve suggesting improvement of bronchial sensitivity without affection of the reactivity. From the obtained data we may suggest that the pollutants in petroleum industry lead to bronchial hyperreactivity and hypersensitivity even in those workers who are not currently complaining. Measurements of pulmonary flow rates is not a sufficient tool, whereas MIC and analysis of the dose- response curve for the slope and the intercept is useful in distinguishing the subjects at high risk from those at low risk