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 98-0153-2883, 2002 Nov; :1-39
On March 17, 1998, the National Institute for Occupational Safety and Health (NIOSH) received a request for a health hazard evaluation (HHE) at Custom Products, Inc. in Mooresville, North Carolina. The request was submitted by the North Carolina Department of Labor, and centered on workers' exposure to 1-bromopropane (1-BP) during the spray application of solvent-based adhesives. In response to this request, NIOSH investigators conducted two surveys at the facility. At the time of the first survey all employees at Custom Products (working in four departments: Saw, Assembly, Sew, and Covers) were considered potentially exposed to 1-BP and 2-bromopropane (2-BP). 2-BP may be found in most commercially available 1-BP formulations as a contaminant. The first survey consisted of exposure, ventilation, and medical assessments. Personal breathing zone (PBZ) sampling for 1-BP was conducted in the Assembly, Covers, and Saw departments, and area air sampling for 1-BP was performed in the Sew department. Air velocity in and around the spray booths and unventilated tables was measured. Other aspects of the ventilation assessment included evaluation of spray booth filter maintenance, and observation of air movement (using smoke tubes), work tasks and movements of workers, and positioning of spray booth exhaust discharges. The medical assessment included questionnaire administration for all employees in the Assembly, Cover, and Saw departments and collection of blood samples and analysis of complete blood count (CBC). A CBC was drawn to determine if 1-BP exposure had any effect on workers' ability to make blood cells. Sixty-nine full-shift, time-weighted average (TWA) 1-BP PBZ exposure measurements and eleven area air samples were collected during the first exposure assessment. The mean 1-BP full-shift PBZ exposure concentration for participating workers was 168.9 parts per million (ppm), and the exposures ranged from 60.0 to 381.2 ppm. All of the exposures were above 25 ppm, a concentration that has been suggested as an exposure guideline by several organizations. On average, the highest exposures were in the Covers department (mean of 197.0 ppm), followed by the Assembly department (169.8 ppm), and the Saw department (117.1 ppm). The mean area 1-BP air concentration in the Sew department was 128.1 ppm. Sprayers (working in the Covers and Assembly departments) were exposed to a higher concentration of 1-BP than were other workers. The initial ventilation assessment found that the Assembly department spray booths (there were no spray booths in the Covers department) were inadequate. During the ventilation assessment, NIOSH investigators identified exhaust filters that were either partially or completely clogged with spray adhesive, observed workers spraying some work pieces outside the spray booths, and found that the spray booth exhaust discharge stacks were located in close proximity to roof-top air intakes. Forty-six (66%) of the seventy employees in the three departments completed the questionnaire and provided blood for a CBC. The median cell counts, platelet counts, and hemoglobin concentrations were all within the normal ranges provided by the laboratory. Several symptoms suggestive of excessive exposure to solvents were prevalent among all workers surveyed; the prevalence of these symptoms was not statistically different between the higher exposed group compared to the lower-exposed group. Thirty-two (70%) of the forty-six medical survey participants had PBZ air sampling for 1-BP; for those thirty-two persons, additional statistical analyses were performed to examine the relationship between individual exposures and the questionnaire and CBC results. The mean 1-BP concentration was not statistically significantly greater among workers reporting symptoms compared to those not reporting symptoms. There were no statistically significant relationships between the individual 1-BP exposure measures and the corresponding CBC results. Several factors, including the fact that all participants in our survey were exposed to 1-BP, limited our ability to assess potential health effects. Subsequent to the first site visit and the interim NIOSH report (May 26, 1999), Custom Products installed new spray booths with local exhaust ventilation for all adhesive spraying operations (Assembly and Covers departments). Follow-up exposure and ventilation surveys were conducted which included both PBZ and area air sampling for 1-BP and 2-BP. The mean 1-BP PBZ exposure concentration at the follow-up survey was 19.0 ppm (range: 1.2 to 58.0 ppm), and a total of 10 (43%) of the 23 1-BP PBZ exposure measurements exceeded 25 ppm. The mean 2-BP PBZ exposure concentration was 0.14 ppm. The 1- BP PBZ air concentrations in the Sew department ranged from 1.1 to 1.9 ppm, and no 2-BP was detected in any of the five samples collected in this department. The average velocity of air flowing into the three spray booths measured during the follow-up ventilation assessment in the Assembly area was approximately 100 ft/min, and the average velocity for the six booths in the Covers area was approximately 125 ft/min. Both of the values are below the recommended 150 ft/min; however, the hoods performed well based on qualitative evaluation. Individual filter average velocities were higher for filter sections that were less clogged by spray adhesive. For work performed inside the booths, air-flow visualization indicated that very little, if any, contaminant would be recirculated into the worker's breathing zone. We found that some pieces were being sprayed outside the booths. The first NIOSH survey documented that all evaluated workers were exposed to 1-BP at concentrations above 25 ppm, and that the old spray booths in the Assembly department were ineffective in reducing workers' 1-BP exposures. Following the installation of new spray booths in the Covers and Assembly departments, the second exposure assessment documented significantly reduced air concentrations of 1-BP, though some employees were still exposed to concentrations of 1-BP above 25 ppm. Some of our ventilation measurements in the follow-up assessment revealed less-than-recommended air velocity in the spray booths, which may have been due to filter clogging by spray adhesive. Analysis of the symptom and CBC data did not show meaningful relationships with 1-BP exposure levels; however, given the limitations of our survey and lack of toxicologic data relevant to 1-BP in general, we are unable to determine if worker exposure to 1-BP at Custom Products constitutes a health hazard. Considering this, and while further data are being collected, NIOSH investigators believe that occupational exposure to 1-BP and 2-BP should be minimized. Implementation of standard engineering, administrative, and work practice controls has been effective in greatly reducing worker exposure to 1-BP. Recommendations are made in this report to further assist in this goal, including recommendations concerning improved employee education and work practices.
Region-4; Hazard-Unconfirmed; Engineering-controls; Control-technology; Ventilation; Ventilation-equipment; Ventilation-hoods; Ventilation-systems; Reproductive-hazards; Reproductive-effects; Solvents; Solvent-vapors; Adhesives;
Author Keywords: Seats: Automobile, Vans, Aircraft, Railroad, and Other Public Conveyances; foam fabrication; spray adhesives; 1-bromopropane; 2-bromopropane; n-propyl bromide; isopropyl bromide; engineering controls; ventilation; spray booths; CBC; complete blood count; headache; reproductive abnormalities