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 2000-0110-2849, 2001 Jun; :1-52
The Hazard Evaluation and Technical Assistance Branch (HETAB) of the National Institute for Occupational Safety and Health (NIOSH) collaborated with the Division of Applied Research and Technology (DART) within NIOSH to conduct a pilot research study evaluating occupational exposure to noise and potential ototoxic agents, such as solvents, metals, and asphyxiants, among a stock car racing team. The purpose of the study was to evaluate exposures to noise and ototoxic agents for their potential combined effect on occupational hearing loss. The exposure assessment included two site visits to the racing team's race shop and two site visits to a racetrack, which represented the worst case exposure scenario due to its small size, steep banking, and high grandstand configuration. An initial site visit was conducted at the professional stock car race team's shop on January 19 and 20, 2000. Air samples were collected to qualitatively and quantitatively identify ototoxic chemicals and other organic compounds. Full-shift and half-shift carbon monoxide (CO) measurements were also collected. Sound pressure levels were measured for the tasks that generated the greatest amount of noise. Noise dosimetry was then conducted to give full-shift personal noise exposures for at least one employee from each job description related to assembling the race car. A follow-up site visit was conducted at the racing team's race shop on February 9, 2000. Full-shift air samples were collected for organic solvents in the paint and body shop areas. A short-term air sample was also collected for lead and 26 other metals and minerals next to a tungsten inert gas (TIG) arc welding station. Noise dosimetry was performed on three workers. Concentrations of toluene, acetone, perchloroethylene, xylenes, styrene, C7-C8 alkanes, and methylene chloride at the race shop were either not detectable or extremely low, and well below any relevant occupational exposure criteria. Mean CO concentrations were well below the Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) of 50 parts per million (ppm), the NIOSH Recommended Exposure Limits (REL) of 35 ppm, and the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) of 25 ppm. The peak concentrations, although elevated, did not exceed the 200 ppm NIOSH ceiling REL. The short-term air sample collected for metals near a welding station revealed no detectable concentrations, with the exception of manganese (which was less than 20% of it's most stringent exposure criteria of 1 milligram per cubic meter of air (mg/m3) as an 8-hour-timeweighted average [TWA]). Sound pressure levels for individual job tasks ranged from 58 to 103 decibels, A-weighted [dB(A)]. While the OSHA PEL of 90 dB(A) for an 8-hour TWA was never exceeded, in two instances the values exceeded the OSHA action level (AL) of 85 dB(A) for hearing conservation implementation. The NIOSH REL of 85 dB(A) for an 8-hour TWA was exceeded for five of the nine measured jobs. Only three of the workers (21%) were observed wearing ear plugs during their work shift. An initial site visit was conducted at Bristol Motor Speedway in Bristol, Tennessee, on March 24 and 25, 2000. Air samples were collected for organic compounds, CO, and lead during the race. Although isopentane, C8 alkanes (isooctane, dimethylhexanes, trimethylpentanes), and toluene were the major compounds detected, the amounts of even these compounds were insufficient to quantify. Mean CO concentrations were well below all evaluation criteria. Air samples collected for lead revealed either non-detectable, or extremely low concentrations, well below the occupational exposure criteria. Noise measurements were performed on both practice and race days (March 24 and 25, 2000, respectively) which included sound level meter measurements and noise dosimetry conducted in and around the pit area, as well as inside the race car. Both the OSHA PEL and NIOSH REL were exceeded in every instance with average noise levels above 100 dB. A follow-up site visit was conducted at Bristol Motor Speedway in Bristol, Tennessee, on August 25, 2000, to measure CO and perform more noise dosimetry. Full-shift mean CO concentrations in some locations exceeded the PEL, REL, and TLV of 39 ppm, 19 ppm, and 27 ppm, respectively, after they were adjusted for a 10-hour day. Peak CO concentrations exceeded the NIOSH recommended ceiling limit of 200 ppm in three of the five sampling locations during the practice period. Peak concentrations in two of the three locations where measurements were collected over the full day also exceeded 200 ppm. Noise dosimetry and sound level meter measurements were also conducted. Both the OSHA PEL and NIOSH REL were exceeded in every instance. Based on the environmental data collected during this pilot study, exposures to potentially ototoxic agents are not high enough to produce an adverse effect greater than that produced by the high sound pressure levels alone. Carbon monoxide levels, however, occasionally exceeded all evaluation criteria at the race track evaluated. In addition, noise exposures occasionally exceeded the OSHA PEL at the team's race shop and exceed all evaluation criteria at the race track evaluated. Recommendations are included to reduce exposures to potentially ototoxic agents that have the likelihood of producing high short-term exposures and to control noise exposures through the use of appropriate strategies (such as wearing hearing protection with a high enough noise reduction rating [NRR] to provide adequate attenuation).