This industrial hygiene summary report summarizes available information about workers who manufactured polychlorinated biphenyl (PCB) filled capacitors at plant 3. Production started in October 1957 and ended in March 1977. Complete work history records for 3,603 workers were microfilmed in March 1977 and 40 personal and 16 area air samples were collected for the evaluation of PCB exposures (NIOSH survey 1977). Capacitor manufacturing began with winding bales of foil, paper, or plastic film in a clean, dust-free room. The bales were placed in a metal capacitor box (pre-assembly), and trays of these pre-fabricated capacitors were placed in a vacuum chamber for impregnation with the dielectric fluid (PCB). Large capacitors, requiring several gallons of dielectric fluid, were filled manually through ports on the top of the capacitor and then loaded into an oven. Impregnation involved placing the capacitor trays in the oven under vacuum to remove moisture, flood-filling the ovens with PCBs, and then heating the PCB oil to a less viscous state. After this soaking cycle, the excess PCB was drained and pressure was re-instated before the warm, wet capacitors were transported to a sealing station. Here the ports were soldered shut (post- or final assembly) and the capacitors were degreased before they were sent off to be leak tested and painted. Changes in the physical plant layout were minor enough to assume little effect on exposure scenarios throughout the PCB operation years. Use of industrial PCB mixtures changed within the time period PCBs were used at this plant. A commercial PCB mixture, such as Aroclor 1242, was used from 1957 through 1971, and Aroclor 1016 was used from 1971 until the dielectric fluid was replaced in 1977. The two mixtures differed in distribution of the chlorination of the congeners, although the average chlorination for Aroclor 1242 and Aroclor 1016 was 41-42%. PCBs vaporized due to the heat from the ovens, and either condensed and settled on surfaces, or the vapors adsorbed directly to surfaces within the facility providing exposure opportunity to workers in the plant whose job tasks did not involve direct contact with liquid PCBs. Other sources of PCB exposure during manufacture of the capacitors were in the leak testing, repair and salvage, and degreasing areas. Dermal exposure intensities were assigned based on opportunity for contact with PCB liquids, job location, total usage, and other task activities. Local exhaust ventilation was provided for soldering and welding operations, and dilution ventilation operated throughout the plant. Overall, there were 884 known job codes: 331 salaried and 553 hourly. Detailed job descriptions for all 553 hourly job codes were obtained. The job descriptions included information on how tasks were performed and what chemicals were used. These jobs were categorized into 19 similar exposure groups. The categories were ordinally ranked on inhalation and dermal exposure separately. The values for the inhalation exposures were derived from the air concentrations measured at the plant in 1977. There was a potential for significant dermal exposure for some jobs. Dermal exposures were rated separately for each job and each category. Dermal exposures were rated in the same general magnitude as inhalation exposures. Both inhalation and dermal exposure estimates were used to develop a combination job exposure matrix (JEM).
National Institute for Occupational Safety and Health, Division of Surveillance, Hazard Evaluations, and Field Studies, Industrywide Studies Branch, Mail Stop R-13, 4676 Columbia Parkway, Cincinnati, OH 45226