Three fatal cases of thinner-sniffing,and experimental exposure to toluene in human and animals

Summary Three fatal cases of organic solvent abuse revealed high levels of toluene in blood and alveolar air and a high level of hippuric acid, metabolite of toluene, in urine. The lethal concentration of toluene was estimated to be 2,000 ppm.Furthermore, 10 male and female volunteer students were exposed to 107 ±12 ppm toluene for 4 hours. Hippuric acid in urine increased with the exposure time and reached maximum 2 hours after initiation of toluene exposure and remained at the same level thereafter. Following cessation of exposure to toluene, hippuric acid in urine showed a rapid decrease and recovered almost to the normal level 4 hours after cessation of exposure.Urinary excretion of hippuric acid in 7 rabbits exposed to 350 ppm for 100 minutes or to 4,500 ppm toluene for 10 minutes, reached its maximum 1.5–2 hours after initiation of exposure and decreased rapidly after cessation of exposure to toluene to recover to the normal level 4 hours later.Read before the 43rd Annual Meeting of Japanese Association of Industrial Health at Tokushima on April 2, 1970, and the 18th Annual Meeting of North Kanto Medical Association at Maebashi on November 14, 1971.