Health hazard evaluation report, HETA-2003-0078-2918, Waste Management, Inc. Outer Loop Landfill, Louisville, Kentucky.
On November 25, 2002, the National Institute for Occupational Safety and Health (NIOSH) received a request for technical assistance from the U.S. Environmental Protection Agency (EPA) regarding a landfill bioreactor study at the Waste Management, Inc. (WMI), Outer Loop Landfill in Louisville, Kentucky. The request concerned landfill dozer and compactor operators' potential exposures during the dumping and spreading of biosolids and sewage sludge at the working face of the landfill. No health effects were reported. In response to this request, NIOSH investigators conducted an initial site visit on December 3, 2002. During a follow-up site visit on June 3-5, 2003, NIOSH conducted air sampling which included the collection of area and personal breathing zone (PBZ) samples for culturable bacteria, endotoxin (a component in cell membranes of Gram-negative bacteria), and volatile organic compounds (VOCs). Samples were collected at the active site of the landfill where waste is disposed and at a capped site no longer receiving waste for comparison. Total bacteria concentrations for the comparison samples and active site samples ranged from 96 colony forming units per cubic meter of air (CFU/m3) to 144 CFU/m3 and from 108 CFU/m3 to >62,304 CFU/m3 respectively. The following enteric bacteria (bacteria present in the intestinal tracts of humans and animals) were identified: Klebsiella oxytoca, Leclercia adecarboxylata, Enterobacter cloacae, and Citrobacter freundii. Exposure to these enteric organisms may result in disease (e.g., gastroenteritis) or in a carrier state in which an infection does not clinically manifest itself in the individual but can be spread to others. Occupational exposure criteria for culturable bacteria have not been established. Area endotoxin samples collected at the active site of the landfill ranged from 2.9 endotoxin units per cubic meter (EU/m3) to 170 EU/m3. The personal breathing zone (PBZ) time-weighted average (TWA) exposure of the dozer operator was 27.9 EU/m3. Occupational exposure criteria for endotoxin, based on observed health effects at measured endotoxin levels, have been suggested at 200 EU/m3 for airway inflamation with increased airway activity, 2000 EU/m3 for over-shift decline in forced expiratory volume in one second, 3000 EU/m3 for chest tightness, and 10,000-20,000 EU/m3 for toxic pneumonitis. NIOSH has not established any recommended exposure limits. Major VOCs detected were ethanol, various aliphatic hydrocarbons, toluene, ethyl benzene, xylenes, trimethyl benzenes, styrene, limonene, and siloxanes. Employees working in the landfill did not report any health problems. A locker room for employees is located in the maintenance shop. Shower facilities are not provided and employees wear their work clothes home. An employee reported they received training on proper hygiene precautions. Suggestions to improve personal hygiene, personal protective equipment, and training are provided in the recommendations section of this report. The environmental monitoring data show that exposure to culturable enteric organisms and endotoxin may occur. Although exposure criteria to evaluate the health implications of these exposures are lacking, reasonable precautions to minimize exposures should be taken. Recommendations are provided to help minimize exposure to sewage sludge and to increase employee awareness of the importance of good hygiene and the appropriate use of personal protective equipment.