Induction of Cytochrome P-450 in Rat Liver After Inhalation of Aromatic Organic Solvents. In: Gut I, Cikrt M, Plaa GL, editors. Industrial and Environmental Xenobiotics. Berlin: Springer Berlin Heidelberg; 1981. pp. 307-17. [DOI: 10.1007/978-3-642-68195-0_36]

Inhalation kinetics of C8 to C10 1-alkenes and iso-alkanes in the rat after repeated exposures

The toxicokinetic properties of C8 and C10 1-alkenes and iso-alkanes have been investigated in rats during inhalation of 100 p.p.m. of the single hydrocarbons for 3 days, 12 hr/day. The concentration of hydrocarbon was measured in blood, brain, liver, kidneys and perirenal fat at days 1, 2 and 3, immediately after exposure and 12 hr after exposure on day 3. The 1-alkenes showed an efficient absorption to blood combined with extensive accumulation in organs, compared to the iso-alkanes. The concentration of 1-alkenes and iso-alkanes in blood, brain, liver and fat increased with increasing number of carbon atoms. The C9 and C10 1-alkenes and iso-alkanes showed increasing concentration in fat during the exposure period and high concentrations 12 hr after cessation of exposure. The extensive accumulation in both blood and organs of 1-alkenes compared to any of the other groups of hydrocarbons may have a toxicologic relevance. Products which contain 1-alkenes should be handled carefully to minimize the risk of inhalation exposure.

Inhalation kinetics of C6 to C10 aliphatic, aromatic and naphthenic hydrocarbons in rat after repeated exposures

The toxicokinetic properties of C6 to C10 n-alkanes, aromates and naphthenes have been investigated in rats during inhalation of 100 p.p.m. of the single hydrocarbons for 3 days, 12 hr/day. The concentration of hydrocarbon was measured by head space gas chromatography in blood, brain, liver, kidneys and perirenal fat at days 1, 2 and 3, immediately after termination of exposure and 12 hr after exposure on day 3. The main conclusions drawn from the study were: a) Aromatic hydrocarbons show high concentrations in blood and low concentrations in organs. b) Naphthenic hydrocarbons show low concentrations in blood and high concentrations in organs. c) n-Alkanes show very low concentrations in blood, relatively high concentrations in brain and a high potential for accumulation in fat with repeated exposures. d) Biological concentrations of hydrocarbons within one class increase in general with increasing molecular weight, though with specific exceptions. e) Accumulation is obviously influenced by differences in metabolism and enzyme induction potential. f) Lipid solubility is not the only parameter relevant for the evaluation of hydrocarbon accumulation.

Accumulation and distribution of aliphatic (n-nonane), aromatic (1,2,4-trimethylbenzene) and naphthenic (1,2,4-trimethylcyclohexane) hydrocarbons in the rat after repeated inhalation

The concentrations of the C9 hydrocarbons n-nonane, 1,2,4-trimethylbenzene and 1,2,4-trimethylcyclohexane were measured in rat blood, brain and perirenal fat after exposures to 1000 p.p.m. of the individual compounds. Measurements were made by head space gas chromatography at the end of 12 hr exposures on days 1, 3, 7, 10 and 14 of the exposure periods. The relative concentrations of hydrocarbons in each organ were, brain: n-nonane "trimethylcyclohexane approximately trimethylbenzene, blood: trimethylbenzene "n-C9 greater than trimethylcyclohexane and perirenal fat: trimethylbenzene greater than n-nonane greater than trimethylcyclohexane, showing the widely different distribution properties of the different hydrocarbons. Brain/blood ratios of 11.4, 2.0 and 11.4, and fat/blood ratios of 113, 63 and 135 were found for n-nonane, trimethylbenzene and trimethylcyclohexane, respectively. A marked decrease in biological concentrations of trimethylbenzene and trimethylcyclohexane during the initial phase of exposure indicate that these hydrocarbons are capable of inducing their own metabolic conversion resulting in lower steady state levels. A special attention was made to n-nonane showing the highest concentration in brain concomitantly with a low blood concentration. This observation demonstrate that biological monitoring of occupational exposure by blood measurements not should be performed without knowledge of the distribution properties of the compounds investigated.