SYMPTOMS AND SIGNS IN WORKERS EXPOSED PREDOMINANTLY TO XYLENES

Surveys were conducted in factories in China where workers were engage d in the production of rubber boots or plastic-coated wire or in print ing work, and were exposed to xylene vapors. Based on the data on expo sure as monitored by personal diffusive sampling, 175 xylene-exposed w orkers (107 men and 68 women) were selected as those (1) who underwent all examinations and (2) for whom the sum of the three xylene isomers accounted for 70% or more of the total exposure (on a ppm basis). The intensity of exposure was such that the sum of the three isomer conce ntrations was 14 ppm as a geometric mean and 21 ppm as an arithmetic m ean. As controls, 241 nonexposed workers (116 men and 125 women) were recruited either from the same factories or from factories in the same regions. There was an increased prevalence of subjective symptoms in the exposed workers which were apparently related to the effects on th e central nervous system and to the local effects on the eyes, the nos e, and the throat, although dose-dependency of the symptoms was eviden t in only a limited number of cases, possibly because the intensity of exposure was rather low. It was further observed that the findings of hematology and serum biochemistry in respect of liver and kidney func tions were generally negative, showing that xylenes are not toxic to t he hematopoietic organs, the liver, or the kidney.