Objectives To evaluate solvent exposures of automotive repair workers and investigate associated neurologic and reproductive effects.

Method Industrial hygienists conducted site-visits, air measurements, and interviews to prepare questions about task frequency, work practices, and products. Participants were recruited from IAMAW. Clinical exams evaluated peripheral neuropathy, neurocognition, colour discrimination, time to pregnancy, and urinary reproductive hormonal metabolites.

Results The 835 participants examined at the BASS clinic had worked over 3000 jobs at 1952 shops. Algorithms were developed to estimate individual solvent exposures in each year by integrating self-reported task frequency with MSDSs, measured and modelled airborne concentrations and dermal absorption. Major temporal changes occurred in source of exposures, e.g., solvent tanks accounted for 71% of solvent exposures in the 1960s, 30% in 2000–04, but only 7% in 2005–2012; concomitantly, exposures from aerosol cans rose from 23% to 64% then 84%, while composition changed dramatically, notably for hexane and perchloroethylene. Hexane was not used prior to 1989 and was eliminated from most products after 2000, when peripheral neuropathy was reported among automechanics. 52% of the automechanics were exposed to hexane for a mean of 5.3 (0.1–12) years, and 80% of these had concomitant exposure to acetone, which potentiates neurologic effects of hexane in rodents. Cumulative hexane exposures were low: mean= 78.1 mg/m³ years (TLV = 176 mg/m³).

Conclusions Work histories were more complex than indicated in the pilot of 39 mechanics. Exposures were significantly affected by temporal trends in cleaning methods, composition of materials, and work practices. Epidemiologic studies must account for these changes.