NONSPECIFIC BRONCHIAL HYPERRESPONSIVENESS AND OCCUPATIONAL AGENTS

The relationship between occupational asthma (OA) and non-specific bro nchial responsiveness (NSBR) is reviewed. Natural or laboratory exposu re to ubiquitous allergens can induce or increase NSBR. Reduction of e xposure has an opposite effect. Preliminary results suggest that NSBR is not a predisposing factor to OA. NSBR assessment can be useful in s creening for OA, before employment to document baseline levels and ser ially afterwards, alone or combined to immediate skin reactivity to th e occupational agent, to document the onset of OA. Showing NSBR is ess ential to the diagnosis of OA. Although specific broncho-provocation t ests in a hospital laboratory still represent the gold standard to con firm OA, the demonstration of changes in peak expiratory flow rates, i n particular if such changes are coupled to NSBR, is an important diag nostic tool. NSBR assessment is also an interesting guide to specific bronchoprovocation in the laboratory. Several studies have documented a reduction in NSBR in some cases of OA after removal from exposure to the causal agent. The degree of NSBR is one of the criteria that have been suggested in setting permanent disability in subjects with OA. I ncreased NSBR can exist in other occupational conditions and represent s an essential feature of Reactive Airways Dysfunction Syndrome (RADS) .