Health hazard evaluation report: HETA-2004-0145-2941, CH2M Hill Hanford Group, Inc. and United States Department of Energy, Office of River Protection, Richland, Washington.
The National Institute for Occupational Safety and Health (NIOSH) received a confidential request from employees of CH2M Hill Hanford Group, Inc., and a subsequent request from the United States Department of Energy, Office of River Protection, to evaluate the potential for exposures and health effects of vapors emitted from hazardous waste storage tanks at the Hanford Site in Richland, Washington. In response to these requests, NIOSH representatives conducted an evaluation at the Hanford Tank Farms in March 2004. The tanks contain a mixture of chemical and radiological waste which is being transferred to another location for processing into glass. Although there is no occupational exposure limit (OEL) for the mixture of chemicals and compounds that may be present in vapor that escapes from the tanks, OELs do exist for some of the individual vapor constituents. NIOSH investigators determined that employees at the Hanford Site may be exposed to vapor mixtures emanating from the "head space" (air space above the tanks’ liquid contents) area of the tanks and that these exposures, on occasion, may be in sufficiently high concentrations to pose a health risk to exposed workers. The tank farm workforce was not routinely provided personal protective equipment (PPE) to protect them from tank vapors. Exposure data for individual workers were limited in quantity and quality, not easily accessible and, in some situations, had not been obtained until hours after an accidental exposure had occurred. Due to these data limitations, the true exposure potential was difficult to ascertain. Of the 54 interviewed workers, 35 reported a variety of acute and chronic health concerns they believed were related to vapor exposures. Those interviewed were also concerned about the available PPE and the adequacy and accuracy of the environmental monitoring which has been performed. To ensure their safety, NIOSH investigators recommend that, at a minimum, a NIOSH approved air purifying respirator be provided to any worker entering a tank farm to protect against exposure to nuisance vapors. For workers entering known vapor release area, higher levels of respiratory protection may be required, such as powered air-purifying respirators equipped with high-efficiency particulate air filters and organic vapor/ammonia cartridges, airline respirators, or self-contained breathing apparatus. NIOSH also recommends that the employer routinely sample the head space of the tanks and conduct personal sampling while the employees are working. Results from this sampling should then be discussed with employees to develop mutually agreeable strategies for further sampling and appropriate personal protection. NIOSH investigators determined a potential for significant occupational exposures and health effects from vapors released from the hazardous waste storage tanks. Although the concentrations of the compounds in the vapor will change over time and during waste movement activities, vapor constituents may be present at sufficiently high concentrations to pose a health risk to workers. Recommendations are given in this report to help protect workers, including providing, at a minimum, air purifying respirators to workers and routinely sampling the head space of the tanks and the personal breathing zones of the workers.