EXPOSURES TO INHALABLE AND TOTAL OIL LIST AEROSOL BY METAL MACHINING SHOP WORKERS

Several recent studies have compared worker personal aerosol exposures as measured by the current method with those obtained by a new approa ch based on collecting the inhalable fraction, intended to represent a ll the particles that are capable of entering through the nose and/or mouth during breathing. The present study investigated this relationsh ip for a metal machining facility where aerosols were generated from s everely refined, nonaqueous (''straight'') cutting oils used during th e lathe working of metal rod stock. Workers (n=23) wore two personal a erosol samplers simultaneously, one of the 37-mm type (far ''total'' a erosol exposure, E(37)) and the other of the Institute of Occupational Medicine (IOM) type (for inhalable aerosol exposure, E(IOM)). The dat a were analyzed by weighted least squares linear regression to determi ne the coefficient S in the relation E(IOM)=S . E(37). lt was found th at S=2.96+/-0.60. This ratio-in which exposure to inhalable aerosol wa s greater than to ''total'' aerosol-is consistent with previous observ ations in other industries. The relative coarseness of the oil mist ae rosol, as estimated by cascade impactor measurements, probably explain s the difference between the sampling methods. The collection of large ''splash'' droplets, may also contribute. Future occupational aerosol standards for metalworking fluids will be based on the new, health-re lated criteria, and exposures will be assessed on the basis of the inh alable fraction. Results of studies like that described here will enab le assessment of the impact on future workplace aerosol exposure asses sments of introducing new standards.