MEASUREMENT OF AIRBORNE RAT URINARY ALLERGEN IN AN EPIDEMIOLOGIC-STUDY

The suitability of radioallergosorbent test (RAST) inhibition to quant ify occupational exposure to rat urinary aeroallergen (RUA) has been a ssessed. When using a constant pool of rat allergic sera, the reproduc ibility of the assay over 1 year was comparable to that reported for o ther immunoassays; at 50% RAST inhibition the inter-assay coefficient of variation (CV) was 7.0% and the intra-assay CV was 3.0%. The assay was highly specific for rat urine; mouse urine was 1100-fold less pote nt at inhibiting the rat urine RAST system. Significant inter-assay va riation in the 'high' control was not due to batch variation and was r elatively small when compared with the variation in RUA concentrations in the occupational environment. Measurement of workplace RUA exposur e demonstrated that those directly involved in the care of rats experi enced the highest RUA exposure of the nine occupational groups studied (animal technicians GM = 23.10 mu g/m(3)) followed in decreasing orde r by those working with soiled litter (e.g. cage cleaners GM = 4.20 mu g/m(3)), dead animals (e.g. post mortem GM = 1.60 mu g/m(3), scientis ts GM = 0.67 mu g/m(3)) and rat tissue (e.g. slide production GM = 0.0 4 mu g/m(3)). In view of the complexity of rat allergens, RAST inhibit ion is an appropriate method for the quantification of occupational ex posure to rats.