Ototoxic occupational exposures for a stock car racing team: I. Noise surveys.

The National Institute for Occupational Safety and Health (NIOSH) surveyed noise exposure for a professional stock car team at their race shop and during two races at one racetrack. At the team's shop, area sound pressure levels (SPLs) were measured for various work tasks. Equivalent levels (Leqs) ranged from 58 to 104 decibels, A-weighted (dBA). Personal noise dosimetry was conducted for at least one employee for each job description in race car assembly (n = 9). The Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) of 90 dBA for an 8-hour, 5-dB exchange rate time-weighted average (TWA) was never exceeded, but in two instances values exceeded OSHA's action level of 85 dBA for hearing conservation implementation. The NIOSH recommended exposure limit (REL) of 85 dBA for a 3-dB exchange rate Leq was exceeded for five of the measured jobs. During the races, SPLs averaged above 100 dBA in the pit area where cars undergo adjustments/refueling, both before and during the race. Peak levels reached 140 dB SPL. NIOSH REL was exceeded for every personal noise dosimetry measurement. Recommendations for hearing protection and communication are presented.

Ototoxic occupational exposures for a stock car racing team: II. chemical surveys.

The National Institute for Occupational Safety and Health (NIOSH) conducted a series of surveys to evaluate occupational exposure to noise and potentially ototoxic chemical agents among members of a professional stock car racing team. Exposure assessments included site visits to the team's race shop and a worst-case scenario racetrack. During site visits to the race team's shop, area samples were collected to measure exposures to potentially ototoxic chemicals, including, organic compounds (typical of solvents), metals, and carbon monoxide (CO). Exposures to these chemicals were all below their corresponding Occupational Safety and Health Administration (OSHA) permissible exposure limits (PELs), NIOSH recommended exposure limits (RELs), and American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit values (TLVs). During site visits to the racetrack, area and personal samples were collected for organic compounds, lead, and CO in and around the "pit" area where the cars undergo race preparation and service during the race. Exposures to organic compounds and lead were either nondetectable or too low to quantify. Twenty-five percent of the CO time-weighted average concentrations exceeded the OSHA PEL, NIOSH REL, and ACGIH TLV after being adjusted for a 10-hour workday. Peak CO measurements exceeded the NIOSH recommended ceiling limit of 200 ppm. Based on these data, exposures to potentially ototoxic chemicals are probably not high enough to produce an adverse effect greater than that produced by the high sound pressure levels alone. However, carbon monoxide levels occasionally exceeded all evaluation criteria at the racetrack.

Self-collected breath sampling for monitoring low-level benzene exposures among automobile mechanics.

Automobile mechanics are exposed to benzene through their contact with gasoline vapor and engine exhaust. This study investigated the benzene uptake associated with these exposures. We first evaluated the reliability of self-collected breath samples among a subset of subjects and found good agreement between these samples and those collected under expert supervision (intraclass correlation coefficient 0.79, n = 69). We then used self-monitoring together with a longitudinal sampling design (with up to three measurements per worker) to measure benzene in air and benzene in end-exhaled breath among 81 workers from 12 automobile repair garages in North Carolina. A statistically significant difference (P < 0.0001, Mann-Whitney rank sum test) was observed between non-smokers and smokers for post-exposure benzene concentration in breath (median values of 18.9 and 39.1 micro g/m(3), respectively). Comparing pre- and post-exposure breath concentrations within these two groups, the difference was significant among non-smokers (P < 0.0001) but not significant among smokers (P > 0.05). Mixed effects regression analysis using backwards elimination yielded five significant predictors of benzene concentration in breath, namely benzene exposure (P < 0.0001), pre-exposure benzene concentration in breath (P = 0.021), smoking status (P < 0.0001), fuel system work (P = 0.0043) and carburetor cleaner use (P < 0.0001). The between-person variance component comprised only 28% of the total variance in benzene levels in breath, indicating that differences among individuals related to physiological and metabolic characteristics had little influence on benzene uptake among these workers.