Influence of different cleaning practices on endotoxin exposure at sewage treatment plants

M.J. Visser, S. Spaan, H.J. Arts, L.A. Smit, D.J.J. Heederik

    Research output: Contribution to journalArticleAcademicpeer-review


    Exposure to endotoxin at sewage treatment plants is associated with an increased prevalence of work-related symptoms in sewage workers. Since cleaning activities are regarded as an important determinant of endotoxin exposure, workers' endotoxin exposure levels during different cleaning activities were compared in an experimental setting. Variables considered were water used (tap water, surface water or effluent), water pressure (low or high pressure, and a fire hose with the mouth open or obstructed), presence of mechanical ventilation and the distance between the worker and the object to be cleaned (concentration gradient). Experimental cleaning scenarios were defined, during which endotoxin exposure was measured with personal and stationary air sampling. Data were statistically analyzed with mixed effects models. The water used for cleaning appeared to have a large influence on endotoxin exposure, especially the use of effluent, which caused a factor 2.4 increase in exposure. Use of high pressure did not significantly add to the exposure. Use of a fire hose with fully opened mouth (spout opening) led to a 3-fold decrease in exposure when compared with a partially obstructed mouth. The presence of mechanical ventilation decreased endotoxin concentration in a room, provided that the capacity of the ventilation system was sufficient. The worker's distance to the object that was cleaned did not significantly influence exposure.
    Original languageEnglish
    Pages (from-to)731-736
    Number of pages6
    JournalAnnals of Occupational Hygiene
    Issue number7
    Publication statusPublished - Oct 2006


    • cleaning
    • effluent
    • endotoxin
    • pressure
    • sewage treatment plant
    • ventilation
    • wastewater


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