Influence of shift work and host factors on endotoxin-related acute peak flow changes

There is limited knowledge about which internal and external factors influe nce respiratory effects of occupational endotoxin exposure. Relationships b etween endotoxin exposure, work-related respiratory symptoms, and acute pea k flow changes were studied in 97 shift workers in the potato processing in dustry. For each worker, across-shift peak flow changes were determined for morning, afternoon, and night shifts. A higher endotoxin exposure was asso ciated with an increased prevalence of work-related symptoms, a smaller pea k expiratory flow (PEF) increase across the morning shift, and a larger PEF decrease across afternoon and night shifts. The largest effects occurred d uring the afternoon shift. No consistent differences between smokers and no nsmokers, and between atopics and nonatopics were observed. We conclude tha t endotoxin exposure in the potato processing industry is related to across -shift peak flow changes and the occurrence of work-related respiratory sym ptoms. The host factors smoking and atopy are not important confounding or effect-modifying factors in these relationships. In respiratory health stud ies among shift workers, it is important to investigate all work shifts bef ore drawing definitive conclusions about exposure-response relationships.