Health hazard evaluation report: HETA 99-0260-2906, Marx Industries, Inc., Sawmills, North Carolina.
In April 1999, the North Carolina Department of Labor (NCDOL), Occupational Safety and Health Division, responded to reports that four employees of Marx Industries, Inc., in Sawmills, North Carolina, had been treated at a local hospital. All four had been evaluated for neurologic symptoms of an unclear cause. Hospital laboratory testing reportedly revealed each to have had elevated levels of bromide ion (Br) in blood and arsenic in urine. A NCDOL investigation found no evidence of occupational exposure to arsenic at Marx. Because of concern that worker exposure to 1-bromopropane (1-BP) (and/or possibly arsenic) at Marx was related to observed health effects, NCDOL submitted a request to the National Institute for Occupational Safety and Health (NIOSH) for a health hazard evaluation (HHE). On November 16-17, 1999, NIOSH investigators conducted an initial site visit, and measured 1-BP and 2-bromopropane (2-BP, also known as isopropyl bromide, found as a contaminant of 1-BP formulations) inhalation exposures to employees working in and near the adhesive spray operations. An additional inhalation exposure assessment was conducted on January 29, 2001. A medical evaluation was performed in January/February 2001 and consisted of (1) a questionnaire survey, (2) collection of blood for a complete blood count (CBC) and to measure whole blood and serum Br concentrations, (3) collection of urine to measure urine Br and arsenic concentrations, (4) nerve conduction testing, and (5) an evaluation of the male reproductive system. NIOSH representatives further investigated potential sources of arsenic exposure at Marx on May 23, 2001. Data from 16 full-shift personal breathing zone (PBZ) samples for 1-BP during the November 1999 exposure assessment (geometric mean [GM] 81.2 ppm; range 18 - 254 ppm) and from 13 full-shift PBZ samples during the January 2001 assessment (GM 45.7 ppm; range 7 - 281 ppm) revealed that most spray-line workers were exposed to 1-BP at concentrations above proposed 25 ppm exposure guidelines during both exposure assessments. PBZ concentrations of 1-BP were lower in January 2001 compared to November 1999, although the difference was not statistically significant. Among unexposed workers (assessed only during the January 2001 survey), none had 1-BP exposures exceeding 5 ppm (GM 1.1 ppm; range 0.1 - 4.9 ppm). Area air sampling in areas adjacent to the spray lines during both surveys found low concentrations of 1-BP, indicating that 1-BP vapors were migrating from the spraying operations. 2-BP concentrations in air were found to be low in both exposure assessments. Forty-three (72% of the 60 workers) persons participated in the questionnaire survey, including 13 workers exposed to 1-BP and 30 workers unexposed. Among these 43, end-of-week and start-of-week serum and urine Br and whole blood Br concentrations were statistically significantly greater among the exposed group compared to the unexposed group, and all were correlated with individual PBZ 1- BP air concentrations. Among the symptoms assessed in the questionnaire survey were symptoms consistent with nonspecific effects of exposure to bromine and/or solvents. Headache was the symptom reported by the most workers (22 workers). We found that symptoms of anxiety (nervousness), feeling drunk, and headache were associated with exposure to 1-BP. Other evaluated symptoms (such as trouble concentrating) were not related to exposure. Forty workers had blood samples analyzed for a CBC. All measures of red blood cells, hemoglobin, and platelets were within the normal ranges provided by the laboratory; one person (unexposed to 1-BP) had a white blood cell count slightly below the lower end of the normal range provided by the laboratory. There were no statistically significant differences in the medians of these parameters between the exposed and unexposed workers and we found no statistically significant relationships between exposure (increasing 1-BP PBZ air or urine Br concentrations) and individual cell counts or hemoglobin concentration. None of the workers completing the questionnaire responded that they had a doctor-diagnosed reproductive or infertility problem. Nine men (50% of the 18 male participants) participated in the laboratory evaluation of male reproductive function, including three exposed workers. Five of the nine men had an abnormal semen analysis; four of these five were unexposed to 1-BP. Analyses to evaluate relationships between measures of exposure (including 1-BP PBZ air concentration and end-of-week urine Br concentration) and the three sperm indices (shape, motility, and number) revealed no evidence of a statistically significant correlation. Forty-two (98%) of the forty-three participants had nerve conduction studies performed. The one worker who did not have nerve conduction testing was unexposed. Of the 42, five (12%) were abnormal. Among the 5 workers with abnormal tests, 2 were among the 13 workers exposed to 1-BP, although neither were sprayers. The prevalence ratio (PR) for an abnormal nerve conduction test among exposed workers was 1.5 (95% confidence interval 0.3 - 7.9). PBZ exposure to 1-BP and end-of-week urine Br concentration were higher among persons with normal nerve conduction testing, although the differences were not statistically significant. Forty-one participants provided urine specimens that were analyzed for total inorganic arsenic. Twelve workers had levels of inorganic arsenic above 25 microg/g creatinine; ten (83%) of those twelve workers had jobs near or on the Springs and Glue Lines. As a result of these data and previous concern about arsenic exposure at Marx, in May 2001 NIOSH investigators conducted a thorough examination of the Marx workplace for a source of arsenic. No arsenic was detected in any of the air, bulk adhesive, or drinking water samples collected during that evaluation. Of the 30 surface wipe samples collected from around the plant, one (collected on the concrete surface of the loading dock) had a detectable quantity of arsenic on it. In this HHE we found inadequate controls of 1-BP exposure and a potential health hazard among employees exposed to 1-BP. Most workers on the adhesive application lines were exposed to 1-BP at concentrations above 25 ppm, and some were exposed to much higher concentrations. These results suggest that the spray-line exhaust fans in place at Marx at the time of the HHE were not adequately capturing the 1-BP vapors generated during the spray adhesive operations. Data from the questionnaire survey suggest that excessive exposure to 1-BP among HHE participants may be related to acute symptoms (such as anxiety [nervousness], feeling drunk, and headache) that have been associated with excessive exposure to bromine or to other types of solvents. We found no evidence for other health effects related to occupational exposure to 1-BP among persons working at Marx during the time of our evaluation. Where NIOSH has conducted surveys in other foam fabrication facilities, implementation of recommended engineering controls has successfully reduced inhalational exposure to 1-BP. Recommendations are made in this report to assist Marx Industries in accomplishing similar results. We found no source of arsenic at Marx and conclude that occupational exposures at Marx are not likely to account for the elevated urinary arsenic levels found among employees.