Hemimellitene (1,2,3-trimethylbenzene) in the liver, lung, kidney, and blood, and dimethylbenzoic acid isomers in the liver, lung, kidney and urine of rats after single and repeated inhalation exposure to hemimellitene.
OBJECTIVE
The aim of the study has been to explore hemimellitene distribution in blood, liver, lung and kidney as well as toxicokinetics of its elimination from blood of rats after single and repeated inhalation exposure to this compound. Tissue distribution and excretion with urine of 2-dimethylbenzoic acids (2,3-DMBA and 2,6-DMBA) were also evaluated.


METHODS
Male outbred IMP:WIST rats were used in the experiment. The animals were exposed to hemimellitene vapors at the nominal concentration of 25 ppm, 100 ppm, and 250 ppm in the dynamic inhalation chambers for 6 h for single exposure purpose and for 4 weeks (6 h/day for 5 day/week) for repeated exposure purposes.


RESULTS
Significantly lower concentrations of hemimellitene were detected in the blood and tissues of animals after repeated inhalation exposure of animals to hemimellitene vapors, which points to reduced retention of the chemical in the lungs of the experimental rats. The trend of hemimellitene elimination from the blood depended solely on exposure intensity, irrespective of exposure time, both after single and repeated exposure. As regards the 2 determined hemimellitene metabolites, the major trend of the metabolic transformation involved formation of 2,3-DMBA.


CONCLUSIONS
The significantly higher urinary 2,3-DMBA concentration after repeated exposure shows that hemimellitene induces enzymatic processes in the rat.
Nofer Institute of Occupational Medicine, Łódź, Poland (Department of Toxicology and Carcinogenesis). radek@imp.lodz.pl.
Radosław
R
Świercz
Nofer Institute of Occupational Medicine, Łódź, Poland (Department of Toxicology and Carcinogenesis). wandam@imp.lodz.pl.
Wanda
W
Majcherek
Nofer Institute of Occupational Medicine, Łódź, Poland (Department of Toxicology and Carcinogenesis). wojciech@imp.lodz.pl.
Wojciech
W
Wąsowicz
D000818:Animals; D001555:Benzene Derivatives / Q000032:analysis* / Q000097:blood; D001565:Benzoates / Q000008:administration & dosage / Q000032:analysis* / Q000652:urine; D019570:Inhalation Exposure / Q000032:analysis*; D007668:Kidney / Q000737:chemistry*; D008099:Liver / Q000737:chemistry*; D008168:Lung / Q000737:chemistry*; D008297:Male; D051381:Rats; D017208:Rats, Wistar
D001555:Benzene Derivatives; D001565:Benzoates; C094650:3,5-dimethylbenzoic acid; C010179:hemimellitene
hemimellitene; inhalation; mesitylene; pseudocumene; rats; toxicokinetic