The effect of insecticide aerosols on lung function, airway responsivenessand symptoms in asthmatic subjects

The object of this study was to compare the effect of standard and "low irr itant" insecticide aerosols on lung function, airway hyperresponsiveness (A HR) and symptoms in asthmatic subjects. A double blind randomized, crossover study was conducted in 25 asthmatic su bjects who reported sensitivity to insecticide aerosols, All subjects were exposed for 30 min, on separate occasions, to two standard insecticide form ulations (A and B), one low irritant formulation (C) and a negative control aerosol. Spirometric function and chest, nose and eye symptoms were record ed during, and for 90 min after, the exposure, AHR to methacholine was meas ured 90 min after the exposure. Compared to the negative control, the maximum fall in forced expiratory vol ume in one second (FEVI) was slightly greater after standard insecticides ( mean differences from control+/-95% confidence interval: aerosol A, 3.3+/-3 .6%, p=0.08; aerosol B, 5.1+/-4.7%, p=0.04), AHR was significantly more sev ere (mean difference from control: aerosol A, 0.35+/-0.29 doubling doses, p =0.028; aerosol B, 0.52+/-0.43 doubling doses, p=0.028), and symptoms were more severe. The low irritant test aerosol (C) did not differ significantly from the negative control with respect to FEVI, AHR or symptoms. It is concluded that some insecticide aerosols trigger symptoms and falls i n lung function in some people with asthma, Furthermore, these aerosols may also increase airway hyperresponsiveness, although the mechanism of this e ffect has not been determined. The low irritant formulation did not appear to have the same effects.