1. In a small factory for vinyl gravure printing using benzene and toluene, 13 workers out of 15 suffered from chronic benzene-toluene poisoning. 2. As an organic solvent only toluene was used in the warm season (May∼October), and toluene containing 5% benzene in the cold season (November∼April), for over 5 years. Before, pure benzene had been used as a solvent. In June of 1964, benzene vapor was hardly detectable in the factory, while the concentration of toluene vapor was as high as 150∼550 ppm. In addition, in a living room on the third floor of the factory, 30 ppm toluene was detected. 3. Three out of four female workers suffered from aplastic anemia, which might have been caused by chronic benzene-toluene poisoning. These patients have worked for over 9 hours being exposed to the toluene vapor of high concentration in the daytime, and stayed in the living room on the second or third floor of the factory being still exposed to the solvent vapor in the night. Their length of such exposures in this factory covers 1∼10 years.

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