ESTIMATION OF HISTORICAL EXPOSURES TO MACHINING FLUIDS IN THE AUTOMOTIVE INDUSTRY

A retrospective exposure assessment study in the automotive parts indu stry conducted in conjunction with a cancer mortality and respiratory morbidity study [Kennedy et al. (1989): Am J Ind Med 15:627-641; Eisen et al. (1992): Am J Ind Med 22:809-824; Tolbert et al. (1992): Scand J Work Environ Health 18:351-360] describes exposure to different type s of machining fluids and selected components that may contribute to t he conditions investigated. A dataset of 394 industrial hygiene measur ements made between 1958 and 1987 was used to estimate past machining fluid levels using a linear statistical model. The effects of differen t plants, machining fluid types, machining operations, and time period s were examined in the model. Separate analyses examined the effects o f different sampling and analysis methods and other measurement variab les. Machining fluid levels prior to 1970 were generally two to five t imes higher than subsequent measurements. The arithmetic mean exposure of all measurements taken before 1970 was 5.42 mg/m3. Arithmetic mean s for different subgroups ranged from 0.59 to 20.28 mg/m3, depending u pon plant, machining fluid, and operation. The arithmetic mean exposur e after 1980 was 1.82 mg/m3 with subgroups ranging from 0.45 to 2.79 m g/m3. Changes in exposure levels generally corresponded with reported changes in plant environments such as installation of enclosures and l ocal exhaust ventilation on machines. (C) 1994 Wiley-Liss, Inc.