Have the prevalence and incidence of occupational asthma and rhinitis because of laboratory animals declined in the last 25 years?

Data for time trends in the prevalence of occupational asthma (OA) and rhinitis (OR) are not known. To investigate trends in the prevalence and incidence of OA and OR over time, we reviewed the available literature. We analysed 15 cross-sectional and 4 longitudinal studies published from 1980 to 2006. In workers exposed to laboratory animals (LA) the prevalence of OA ranged from 2.2% to 11.7%; the prevalence of OR ranged from 6.7% to 41.7%. When we analysed prevalence by study date using a logistic model, the estimated prevalence of OA declined from 8.7% in 1976 to 4.2% in 2001 (p < 0.003), which is -1.8% every ten years. The prevalence of OR rose slightly from 18.5% in 1976 to 19.7% in 2001 (NS). In four longitudinal studies the incidence of OA ranged from 0.4 to 3.5/100 person years, while the incidence of OR ranged from 2.0 to 10.1/100 person years. No clear trend emerged over time. This review shows a trend toward a progressive decline in the prevalence of occupational asthma due to laboratory animals, which may be due to the reduction of exposure since the early 1980s. A further reduction of exposure is needed to prevent the onset of occupational rhinitis.