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Characterization of hydrogen sulfide and endotoxin exposure at three wastewater sewage treatment plants.

Marlow D
American Industrial Hygiene Conference and Exposition, May 19-23, 1997, Dallas, Texas. Fairfax, VA: American Industrial Hygiene Association, 1997 May; :5-6
Investigators for the National Institute for Occupational Safety and Health (NIOSH) conducted. health hazard evaluations (HHEs) at three municipal wastewater sewage treatment plants. These evaluations were conducted in response to reported worker health symptoms including periodic headaches, burning sensation in the nose, shortness of breath, sore throat, eye irritation, nausea, and diarrhea. Personal breathing zone (PBZ) and area air samples were collected for hydrogen sulfide using passive monitors with electrochemical sensors and data loggers. Personal breathing and area air samples also were collected for endotoxin using tared, S.O-micrometer pore size, 37-millimeter diameter, polyvinyl chloride filters operated at a volumetric airflow rate of 1.5 liter per minute. Each filter sample was extracted with sterile, nonpyrogenic water with supernates being analyzed for endotoxin by quantitative chromogenic Limulus amebocyte lysate test. Maximum PBZ hydrogen sulfide concentrations ranged from nondetectable (ND) to 124 parts per million air (ppm). Ten of 21 PBZ sample results for hydrogen sulfide exceeded the NIOSH recommended exposure limit (REL) (the NIOSH REL for hydrogen sulfide is a ceiling concentration of 10 ppm, which must not be exceeded during any part of the workday), and 7 of the 21 samples exceeded the OSHA permissible exposure limit (PEL) (the Occupational Safety and Health Administration (OSHAI PEL for hydrogen sulfide is a ceiling limit of 20 ppm). The highest exposures to hydrogen sulfide occurred while working in sludge dewatering and incineration operations. The 124 ppm hydrogen sulfide concentration, which exceeds the immediately dangerous to life or health concentration of 100 ppm, was measured on a maintenance worker performing repairs in the sludge dewatering operations. Time-weighted average personal breathing zone concentrations for endotoxin ranged from ND to 10.9 endotoxin units per cubic meter of air (EU/m3). No REL or PEL has been established for endotoxin. Rylander suggested a maximum exposure limit of 100 EU/m3. These levels were well below this suggested exposure limit. Based on the overexposures to hydrogen sulfide, recommendations made included the use of personal monitors for hydrogen sulfide for those workers with exposure that exceeded 5 ppm, and the use of the appropriate respirator when hydrogen sulfide concentrations exceeded 10 ppm.
Hazards; Health-hazards; Waste-treatment; Waste-disposal-systems; Exposure-levels; Exposure-limits; Workers; Worker-health; Air-samples; Monitors; Electrochemical-properties; Endotoxins; Filters
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American Industrial Hygiene Conference and Exposition, May 19-23, 1997, Dallas, Texas
Page last reviewed: May 11, 2023
Content source: National Institute for Occupational Safety and Health Education and Information Division