Airborne Endotoxin Predicts Symptoms in Non–Mouse-sensitized Technicians and Research Scientists Exposed to Laboratory Mice

Research scientists, laboratory technicians, and animal handlers by either prick skin testing (PST) or RASTs to animal allerwho work with animals frequently report respiratory and skin symp- gens (4, 7, 9–11). Although some animal-related eye, chest, toms from exposure to laboratory animals (LA). However, on the and skin symptoms have been associated with higher allergen basis of prick skin tests or RASTs, only half are sensitized to LA. exposure and atopy in the host (3, 7), nasal symptoms often We hypothesized that aerosolized endotoxin from mouse work is have not (12–14). These findings suggest that there may be responsible for symptoms in nonsensitized workers. We performed environmental triggers for work-related symptoms other than a cross-sectional study of 269/310 (87%) workers at a research animal allergens. institution. Subjects completed a questionnaire and underwent LA workers are exposed to a complex mixture of allergens prick skin tests (n 254) or RASTs (n 16) for environmental and and irritants, including endotoxin, volatile organic comLA allergens. We measured airborne mouse allergen and endotoxin pounds, ammonia, and fecally contaminated particulates, in the animal facility and in research laboratories. Of 212 workers among others. Past evidence suggests that volatile organic not sensitized to mice, 34 (16%) reported symptoms compared with compounds and ammonia levels are generally below levels 26 (46%) of mouse-sensitized workers (p 0.001). Symptomatic that should trigger health effects in animal facilities (15). workers were more likely to be atopic, regardless of mouse sensitiza- Airborne endotoxin has been shown to induce respiratory tion status. Symptomatic non–mouse-sensitized workers spent symptoms (16–19), and in at least three prior studies of a more time performing animal experiments in the animal facility (p LA workplace, airborne endotoxin was detected (20–22). We 0.0001) and in their own laboratories (p 0.0001) and had higher hypothesized that aerosolized endotoxin triggers nasal and daily endotoxin exposure (p 0.008) compared with asymptomatic other symptoms in technicians and research scientists during coworkers. In a multivariate model, daily endotoxin exposure most experimental work with and care of LA, particularly in those strongly predicted symptoms to mice in non–mouse-sensitized workers not sensitized to LA. This study addresses the disworkers (odds ratio 30.8, p 0.003). We conclude that airborne crepancy between symptoms and LA allergy and explores endotoxin is associated with respiratory symptoms to mice in non– the role of endotoxin as well as mouse allergen in causing