Occupational challenge studies with laboratory workers allergic to rats.

To relate airborne Rat N I concentrations to airway responses in allergic laboratory workers, we collected allergen on personal monitors while workers and control subjects were exposed in a rat vivarium for 1 hour. Allergen concentrations ranged from less than 1.5 to 310 ng/m3 and were significantly (p less than 0.001) higher during cage cleaning (19 to 310 ng/m3) than during quiet activity (less than 1.5 to 9.7 ng/m3). Among 12 rat-allergic volunteers, all had a nasal response during the exposure with an increase in nasal lavage histamine concentrations or TAME-esterase activity, but only five volunteers had a lower respiratory tract response (fall in FEV1 greater than 10%). Two of five allergic control subjects had a small change in nasal TAME-esterase activity, and none had a 10% fall in FEV1. A dose response was demonstrated between the allergen concentrations and the intensity of the nasal allergic response. This occupational challenge procedure thus was able to measure the nasal and lower respiratory tract response to airborne allergen exposure in a work environment. It can be used to define further the determinants of this response.