The control of perchloroethylene (127184) (PERC) exposure in commercial dry cleaning through machine design was reviewed. Health hazards associated with PERC included central nervous system depression, liver and kidney damage, memory impairment, dermatitis, respiratory irritation, and other symptoms. Dry cleaning machine types included first generation transfer machines, second generation dry to dry vented machines, third generation dry to dry nonvented machines, fourth generation dry to dry nonvented machines with secondary vapor control, and fifth generation dry to dry nonvented machines with secondary vapor control and drum monitors. Dry cleaning machines evolved over time from the first through fifth generations, becoming safer with each successive generation. The manual transfer of clothing required with transfer machines was eliminated with dry to dry machines. The development of nonvented dry to dry machines utilizing refrigerated condensers led to considerable solvent savings and PERC emissions reduction. Residual PERC present in the machine cylinder at the end of the dry cycle was reduced via a refrigerated condenser plus carbon absorber in dry to dry nonvented machines with secondary vapor control. Fifth generation machines were essentially fourth generation machines in which the vapor concentration in the machine drum was monitored. The current OSHA permissible exposure limit for PERC was an 8 hour time weighted average exposure of 100 parts per million (ppm). Only fourth and fifth generation machines were able to keep worker exposures below the OSHA maximum peak of 300ppm. Important machine design features included a dry to dry design, primary and secondary vapor control systems, a drying sensor that monitored solvent recovery, and a door locking mechanism for the loading and unloading door of the dry cleaning machine. The retrofitting of refrigerator condensers or carbon absorbers was a less expensive option to buying new equipment.
NIOSH Hazard Controls, No. HC18, NIOSH, U.S. Department of Health and Human Services, DHHS (NIOSH) Publication No. 97-156, 4 pages