Trans,trans,-muconic acid in occupational exposure modeling

The objective of this study is to assess the external and internal exposures to aromatic hydrocarbons in the cistem cleaning and cistern mechanic repair processes at a coke plant. 149 workers engaged as operators in cistem cleaning and cistern mechanic repair processes and 35 non-exposed subjects were examined. Personal analyses of the benzene, toluene, xylene isomers, ethylbenzene, PAH's and aldehydes in the breathing zone air allowed us to determine the time weighted average exposure levels to the aromatic hydrocarbons listed above. The internal exposure to benzene was investigated by measurement of the urinary excretion of tt-MA by means of high pressure liquid chromatography (HPLC). Time of workers exposure to chemicals, work energetic cost and dietary customs of workers including also smoking and alcoholic beverages consumption were monitored during the experiment. The time-weighted average concentrations of the hydrocarbons detected in the breathing zone air shows that the exposure levels of the workers are relatively high in comparison to the exposure limits. Statistically significant correlations of tt-MA concentration in urine and benzene concentration in the breathing zone air (Pearson r= 0,832, n= 141, p < 0,001) determined at the workplaces in the cistern cleaning department and cistem mechanic repair department have been found. Concentrations of the benzene, toluene and ethylbenzene detected in workers from the cistem mechanical repair department are higher that those from the cistern cleaning department Concentrations trans,trans-muconic acid (tt-Ma), in the urine of occupationally exposed workers were significantly higher than those of non-exposed subjects. Concentrations of tt-MA in urine were significantly higher for the cistern cleaning workers. Operators at the cistern cleaning and cistern mechanical repair processes are simultaneously exposed to a mixture of different hydrocarbons, and aldehydes.