Health hazard evaluation report: HETA-2007-0331-3100, evaluation of potential exposures at an electrolytic manganese dioxide processing plant, Erachem Comilog, Inc., New Johnsonville, Tennessee.
NIOSH received an HHE request from a representative of the International Union of Operating Engineers Local 369 at Erachem Comilog, Inc., in New Johnsonville, Tennessee. The requestors were concerned about exposure to cobalt and nickel in the filter mud, manganese dust in the production areas, and sulfuric acid mist in the cell rooms. The health effects reported were cancer, lung problems, skin and eye irritation, nausea, and exhaustion. We conducted site visits in October 2007, February 2008, and August 2008. On October 24-25, 2007, we toured the facility to observe work processes, work practices, and PPE use. Confidential medical interviews were conducted with 11 employees, and 4 PBZ air samples were collected for sulfuric acid. We reviewed previous air sampling records, injury and illness records, and the respiratory protection and hearing conservation programs. During the February 20-22, 2008, site visit, we collected 16 full-shift PBZ air samples for sulfuric acid and 13 full-shift PBZ air samples for dust to evaluate employee exposure to metals such as manganese, cobalt, and nickel. We also conducted task-based air sampling by collecting four PBZ air samples for metals on employees performing job tasks associated with dropping and drumming the filter mud and spray washing the filters. During the August 25-28, 2008, site visit we collected 50 full-shift PBZ air samples, 2 full-shift GA air samples, and 3 task-based air samples for dust-containing metals over the morning and night shifts. We found that 2 PBZ air samples for manganese exceeded the NIOSH REL of 1 mg/m3, and 16 exceeded the ACGIH TLV of 0.2 mg/m3. The highest PBZ concentrations of manganese were among operators working in the product preparation area, ore trammers, and CCOs in the digest area of the plant. Of the 33 PBZ air samples collected from employees (CCOs and product preparation operators) working 12-hour shifts, seven exceeded the ACGIH TLV of 0.2 mg/m3. However, if the ACGIH TLV for manganese is adjusted to account for the 12-hour work shifts, 16 PBZ air samples would have exceeded the adjusted TLV of 0.1 mg/m3. In addition, a 30-minute task-based sample collected when an employee was bagging the final product exceeded the ACGIH excursion limit of 0.6 mg/m3. Employees' full-shift and task-based exposures to cobalt, nickel, and sulfuric acid were very low and below their applicable OELs. We also found that the respiratory protection and hearing conservation programs had deficiencies. The written respiratory protection program did not accurately reflect actual employee PPE use. Interviewed employees were concerned about cancer risk, upper airway irritation from exposure to sulfuric acid mist, and safety when working in cell rooms. Four out of 11 employees reported nosebleeds when exposed to the sulfuric acid mist. Review of the OSHA Form 300 Log of Work-Related Injuries and Illnesses for the years 2002-2007 showed entries for chemical and thermal burns, falls, and musculoskeletal injuries such as sprains and strains. We found no cases of chronic manganese, cobalt, or nickel poisoning. We recommend installing local exhaust hoods for the bag filling operation and using existing local exhaust hoods when cutting and grinding parts. We recommend that employees with job titles exceeding the OELs for manganese wear a minimum of a NIOSH-approved half-mask air purifying respirator with N95 or higher filter efficiency until engineering controls reduce exposure below the OELs. We also recommend using nonreactive fiber-reinforced plastic covers to reduce the amount of acid mist and steam generation. Until the plastic covers are installed, management should place barricades along the full length of the cell tank to as a warning and to prevent employees from falling into the cell tanks. Employees could be also provided with crane-mounted fixed/extendable walkways to conduct their job safely in cell rooms. Additionally, we recommend revising the written respiratory protection program to address inconsistencies between the written program and the employees' current respirator use.