[The toxic hygiene problems of workers in the Dinamik automobile tire plant in Sofia]

Toxic hygienic investigations were carried out involving a representative group of 131 workers (50 females and 81 males) distributed into three main workshops--preparatory, confection, and vulcanization--at "Dynamic" automobile tire plant in Sofia. The majority of male and female workers were in the age range beyond 40 years, having a general occupational experience in excess of 10 years and specialized occupational experience from 10 to 20 years or more. The chemical hazard was among the leading ones in the occupational environment, differing in nature according to the technologies used. Included were various chemical substances and compounds: synthetic rubbers, fillers (soot, chalk, kaolin); softeners (mazut, paraffin, etc.); accelerants (mercaptothiazoles--captax and altax); dithiocarbamates (thiuram); vulcacides (diphenylguanidine); antiwear agents (antioxidants and antiozonators-isopropyl-phenyl-paraphenylene diamine, naphthyl-beta-naphthylamine); antiaccelerants (phthalic anhydride, ets.); organic solvents and others. The indicated chemical substances and compounds, though often found at concentrations below the mean-shift MACs, do produce health impacts by virtue of prolonged and combined exposures. Use was made of the questionnaire method. Also, hematologic, clinical laboratory, and toxic chemical testing was performed. Findings pointed to changes in hemopoiesis, deviations in hepatic functional state, while sulfate and glucuronide values confirmed the workers' high exposures.