Evaluation of COSHH essentials: methylene chloride, isopropanol, and acetone exposures in a small printing plant.

The current study evaluated the Control of Substances Hazardous to Health (COSHH) Essentials model for short-term task-based exposures and full-shift exposures using measured concentrations of three volatile organic chemicals at a small printing plant. A total of 188 exposure measurements of isopropanol and 187 measurements of acetone were collected and each measurement took approximately 60 min. Historically, collected time-weighted average concentrations (seven results) were evaluated for methylene chloride. The COSHH Essentials model recommended general ventilation control for both isopropanol and acetone. There was good agreement between the task-based exposure measurements and the COSHH Essentials predicted exposure range (PER) for cleaning and print preparation with isopropanol and for cleaning with acetone. For the other tasks and for full-shift exposures, agreement between the exposure measurements and the PER was either moderate or poor. However, for both isopropanol and acetone, our findings suggested that the COSHH Essentials model worked reasonably well because the probabilities of short-term exposure measurements exceeding short-term occupational exposure limits (OELs) or full-shift exposures exceeding the corresponding full-shift OELs were <0.05 under the recommended control strategy. For methylene chloride, the COSHH Essentials recommended containment control but a follow-up study was not able to be performed because it had already been replaced with a less hazardous substance (acetone). This was considered a more acceptable alternative to increasing the level of control.