Endotoxin exposure and symptoms in wastewater treatment workers.

BACKGROUND Wastewater treatment workers can be exposed to biological and chemical agents resulting in work-related health effects. The aim of this study was to investigate work-related symptoms in these workers. METHODS Questionnaire data of 468 employees from 67 sewage treatment plants is evaluated. Personal endotoxin exposure (8 hr measurements; n = 460) was measured in a sample of workers in three different periods over 1 year. RESULTS Endotoxin exposure ranged from 0.6 to 2093 endotoxin units (EU)/m(3), the geometric mean exposure was low (27 EU/m(3)). Factor analysis yielded three clusters of correlated symptoms: "lower respiratory and skin symptoms," "flu-like and systemic symptoms," and "upper respiratory symptoms." Symptoms appeared to be more prevalent in workers exposed to endotoxin levels higher than 50 EU/m(3). A significant dose-response relationship was found for "lower respiratory and skin symptoms" and "flu-like and systemic symptoms" (P < 0.05). CONCLUSIONS Wastewater treatment workers reported a wide range of symptoms that may be work-related. Microbial exposures such as endotoxin seem to play a causal role.