Monitoring risks in association with exposure levels among wastewater treatment plant workers

OBJECTIVE: To investigate the relationship between exposure to hydrogen sulfide and endotoxin during specific job tasks and health symptoms among wastewater treatment plant (WWTP) workers. METHODS: The exposure levels for specific tasks were measured by personal monitoring. The health symptoms of WWTP workers were compared with those of water treatment plant workers through a questionnaire survey. RESULTS: Exposure levels for all monitored tasks were less than 1 ppm for hydrogen sulfide and 91 EU/m (endotoxin units/m) for endotoxin. Statistically higher odds ratios of respiratory, ocular and skin irritation, neurology, and gastrointestine symptoms were shown among WWTP workers compared with water treatment plant workers. Tasks related to sludge handling and plant inspection showed statistically significant associations with memory/concentration difficulties, throat irritation, and stomach pain. CONCLUSIONS: These results suggest that exposure control programs for specific job tasks and work locations are needed.