Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, HETA 97-0196-2755, 1999 Oct; :1-46
On May 7, 1997, the (NIOSH) received a request for a health hazard evaluation (HHE) at Astoria Metal Corporation (AMC) located at Hunters Point Naval Shipyard in San Francisco, California. The request, which was submitted jointly by AMC management and the International Brotherhood of Boilermakers, raised concerns about repetitive motion injuries and metal exposures during welding, torch cutting, grinding, and abrasive blasting operations. Due to an ongoing OSHA investigation, NIOSH did not conduct a site visit until April 1998. On April 1, 1998, NIOSH researchers conducted an industrial hygiene and ergonomic evaluation on ships being repaired or dismantled on Dry Dock #4, to identify specific work areas and job tasks and to devise an air sampling and ergonomic evaluation plan. On April 2 and 3, 1998, personal breathing zone (PBZ) air samples and bulk paint chip samples were collected for metals analysis. NIOSH investigators also reviewed the lead and respiratory protection programs, and the OSHA 200 Log and Summary of Occupational Illnesses and Injuries. An ergonomic evaluation was conducted on selected employees performing welding tasks on Dry Dock #4, and on three office workers performing administrative duties that involved the use of personal computers. PBZ air samples were collected from AMC workers performing job tasks involving welding, grinding, and torch cutting. In the process area, three workers were monitored while torch cutting (with oxygen and propane) large metal structures (gimbal assembly) removed from the superstructure of the Glomar Explorer. In the dry dock, five workers were monitored while retrofitting and repairing two barges; two workers were underneath the barges and three were inside the barge tanks. Work activities included stick and metal inert gas (MIG) welding of new materials onto the barge. Also in the dry dock, two workers onboard the U.S.S. Ashtabula were monitored while torch cutting and removing non-ferrous materials such as brass, copper, and aluminum from the engine room. PBZ air sample results (8-hr, time -weighted averages (TWAs)) are separated into four work areas: the U.S.S. Ashtabula, the process area, inside the barge tank, and under the barge. On the U.S.S. Ashtabula, all four PBZ air sample lead concentrations exceeded the NIOSH recommended exposure limit (REL), OSHA permissible exposure limit (PEL), and the ACGIH threshold limit value (TLV) of 50 micrograms per cubic meter (ug/m3), with lead concentrations ranging from 253 to 435 ug/m3. Cadmium concentrations ranged from 10 to 61 ug/m3: all four PBZ air sample concentrations exceeded the PEL of 5 ug/m3 and TLV of 10 ug/m3. NIOSH considers cadmium to be a potential occupational carcinogen, and recommends that exposures be reduced to the lowest feasible levels. The highest lead and cadmium concentrations were collected from the worker torch cutting and removing non-ferrous materials. Nickel concentrations ranged from 14 to 55 ug/m3, with three of four PBZ air sample concentrations exceeding the REL of 15 ug/m3. Copper concentrations ranged from 168 to 362 ug/m3, with all four PBZ air sample concentrations exceeding the REL and the PEL of 100 ug/m3. The highest nickel and copper concentrations were collected from the firewatcher. In the process area, lead concentrations ranged from 41 to 399 ug/m3; four of five PBZ air sample concentrations exceeded the REL, PEL, and TLV of 50 ug/m3. Cadmium concentrations ranged from less than concentrations ranged from 1 to 43 ug/m3; three of five PBZ air samples exceeded the REL of 15 ug/m3. Copper concentrations range from 6 to 63 ug/m3; all five PBZ air sample concentrations were below the REL and the PEL. In the barge tank, lead concentrations ranged from 79 to 356 ug/m3; all five PBZ air sample concentrations exceeded the REL, PEL, and TLV. Nickel concentrations ranged from less than 0.6 to 3 ug/m3; all PBZ air sample concentrations were below relevant evaluation criteria. Manganese concentrations ranged from 82 to 873 ug/m3; four of five PBZ air sample concentrations exceeded the TLV of 200 ug/m3. Copper concentrations ranged from 11 to 19 ug/m3; all five PBZ air sample concentrations were below relevant evaluation criteria. Under the barge, lead concentrations ranged from less than 0.6 ug/m3 to 2.5 ug/m3; all four PBZ air sample concentrations were below relevant evaluation criteria. All nickel concentrations were below the minimum detectable concentrations (MDC) of concentrations ranged from 46 to 75 ug/m3; all PBZ air sample concentrations were below relevant evaluation criteria. Copper concentrations ranged from 2 to 5 ug/m3 and were below all relevant evaluation criteria. Workers performing tasks that involved welding, grinding, or torch cutting wore NIOSH-approved half-face, air-purifying respirators equipped with organic vapor and high efficiency particulate air (HEPA) filters. NIOSH has given these respirators an assigned protection factor (APF) of 10. Therefore, the maximum use concentration (MUC) for these respirators for lead is 500 ug/m3 as an 8-hr TWA (OSHA PEL of 50 ug/m3 x APF of 10 = 500 ug/m3). The MUC for cadmium is 50 ug/m3 as an 8-hr TWA. Based on this information, if the respirators are properly fitted to the workers and used in conjunction with a comprehensive respiratory protection program, personal exposures to lead, nickel, copper, and manganese would be expected to be below the occupational exposure limit. However, two of four PBZ air sample concentrations collected from workers on the ship exceeded the MUC of 50 ug/m3 for cadmium for these respirators.