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Long-term deficits in visuospatial function and memory and disturbances in mood have been clinically identified and followed in four patients occupationally exposed to perchloroethylene (PCE). A frontal/ limbic hypothesis is offered as the site of pathology. A separate study among 65 dry cleaners was conducted to provide similar evidence of impairment, suggesting a continuum between clinical and preclinical effects. Three exposure zones were identified for the counter clerks, pressers, and operators corresponding to air levels of 11.2, 23.2, and 40.8 ppm. Decrements were found for visual reproductions (14.4%), the number correct (6.7%) and the latency (10%) for pattern memory, and the number correct (3.9%) for pattern recognition. Chronic, life-long deficits appear below 50 ppm and require at least 3 years of exposure. A reexamination of the OSHA standard is recommended and shows that behavioral testing can be used as an early indicator of more serious clinical effects.