Health hazard evaluation report, HETA-2000-0233-2845, Trilithic, Inc., Indianapolis, Indiana.
On April 7, 2000, the National Institute for Occupational Safety and Health (NIOSH) received a confidential employee request for a health hazard evaluation (HHE) at Trilithic, Inc., in Indianapolis, Indiana. The request centered on health effects possibly associated with the introduction of a new solvent called NPB in the cold vapor degreaser. The solvent contained 1-bromopropane (1-BP, also called n-propyl bromide), which is commonly contaminated with 2-bromopropane (2-BP, isopropyl bromide). The NIOSH investigators conducted site visits on July 18, and November 8, 2000. During the latter site visit, 1-BP and 2-BP personal breathing zone and area air concentrations were measured to determine employees' exposures to these compounds when cleaning small parts in the cold vapor degreaser. Approximately one year before submission of the NIOSH HHE request, Trilithic changed the degreaser's cleaning solvent to a product containing 1-BP. Soon after the change in solvents, employees working in and near the assembly areas experienced headaches, nausea and vomiting, near syncope ("feeling faint"), and mucous membrane irritation. In response, Trilithic built a room to enclose the degreaser. In addition, a local exhaust ventilation system was installed to vent the vapors from within the room to the outside of the building. Construction of the ventilated room was completed approximately 3 months prior to the initial NIOSH site visit. At the time of the initial NIOSH site visit in July 2000, neither management representatives, nor the worker representative nor the requestor were aware of ongoing or persistent health complaints. Full-shift time-weighted average 1-BP and 2-BP exposure measurements were obtained from 20 assemblers in the Components, Tech Station, Engineering Support, Filters, Custom Filters, and Tunables Departments. The 1-BP exposures ranged from 0.01 parts per million (ppm) to 0.63 ppm, and 13 of the measurements (65%) were equal to the minimum quantifiable concentration (0.02 ppm) or less. All the 2-BP exposure measurements were below the minimum detectable concentration (MDC) of 0.004 ppm. Two short-term, task-based 1-BP exposure measurements obtained from employees using the degreaser were 2.3 and 8.4 ppm. No 2-BP was detected in either of these samples (short-term 2-BP MDC was 0.06 ppm). Area air sampling was conducted in the degreaser room, and in areas adjacent to that room. The highest area air concentrations were found in the samples collected in the degreaser room. A 1-BP concentration of 4.42 ppm and a 2-BP concentration of 0.02 ppm were found at the degreaser, and a 1-BP concentration of 1.7 ppm was found 5 feet from the degreaser. All other 1-BP and 2-BP concentrations were either very low, or no analyte was detected. Based on the current knowledge concerning occupational exposures to 1-BP and 2-BP, the NIOSH investigators conclude that there is no current health hazard related to the use of NPB in the cold vapor degreaser at Trilithic. Recent enclosure of the cold vapor degreaser and improvements in ventilation appear to have effectively controlled levels of 1-BP. Moreover, improved work practices (allowing parts to more thoroughly drip dry prior to transporting them out of the room containing the degreaser unit) may have also served to decrease exposure to 1-BP. Since the degreasing operation was enclosed and the local exhaust ventilation improved, the previously reported nonspecific symptoms and health effects appear to have resolved.