Exposure to isophorone and other organic solvents in a screen printing plant

A study was conducted in a screen printing plant to determine the exposure of workers to isophorone and other organic solvents. One hundred twenty-four charcoal tube samples were collected from both workers breathing zones and various workplace areas. Sampling times were 50-90 minutes. Maximum mean TWACs of isophorone and cyclohexanone were 23 +/- 5.4 ppm and 28 +/- 5 ppm, respectively, at the breathing zones of printing press workers. Exposure levels for other organic vapors such as cellosolve acetate, butyl acetate, xylenes, diacetone alchohol, and petroleum distillate are also presented. Mean TWACs of personal samples were generally higher than area samples due to proximity of the solvent evaporating surfaces to the workers breathing zones. Mean TWACs for the individual organic vapors did not exceed OSHA Limits. However, the sum of (TWAC/TLV) ratios of organic vapors with additive health effects exceeded unity at the breathing zones of workers handling inks and solvents. Actual 8-hour worker exposures were assumed to be lower because workers were exposed to lower concentrations (about 9/10 of the additive TLVs) in the plant's general atmosphere during non-active periods of the work shift. Recommendations for improvement of working conditions and reduction of exposure levels are made.