Differences in kinetics of pure and soil-adsorbed toluene in orally exposed male rats

Assessment of health risk following exposure to chemically contaminated soil has primarily utilized results from studies conducted with pure chemicals. However, complex interactions with soil may alter the way in which a chemical subsequently interacts with the body. This study was conducted to determine if adsorption to either of two New Jersey soils qualitatively or quantitatively altered the way in which toluene is absorbed, distributed, metabolized or excreted by the body following oral exposure. Adult, male rats were gavaged with an aqueous suspension of 14C-toluene in the presence or absence of either an Atsion (sandy soil) or a Keyport soil (clay soil). Both soils reduced the peak plasma concentration of radioactivity, while sandy soil also reduced the time to reach peak vs toluene alone. Clay soil produced a statistically significant decrease in the half-life (t1/2) of elimination of radioactivity from plasma vs toluene alone. However, neither soil altered the area under the plasma radioactivity-time curve (AUC) vs toluene alone. Three-h post administration, stomach and fat contained the highest concentrations of radioactivity. No differences were detected in the tissue concentrations of radioactivity between the treatment groups. Urine was the primary excretion route of radioactivity in all treatment groups with lesser amounts excreted in expired air and negligible amounts in feces during the 48 h following exposure. Unmetabolized toluene represented greater than 98.8% of radioactivity in expired air of all treatment groups. Clay soil produced a statistically significant decrease in the excretion of radioactivity in expired air at the 0-1, 0-12, 0-24 and 0-48 periods vs toluene alone.(ABSTRACT TRUNCATED AT 250 WORDS)