Soil Adsorption Alters Bioavailability of Benzene in Dermally Exposed Male Rats

Publisher Website
Google Scholar
Abstract
The potential for exposure to chemically contaminated soil is a concern for chemical industry and were disposal site workers as well as for individuals living near the contamination site. Current assessment of potential health risks from these types of exposures relies almost exclusively on extrapolations from data derived with pure chemicals. Complex interactions with soil, however, may alter greatly the way in which a chemical subsequently interacts with the body. This study was conducted to determine if soil adsorption alters the way in which benzene, a common chemical contaminant, enters and is handled by the body following dermal exposure. A shallow glass cap covering approximately a 13-cm2 area was fixed tightly to the shaved skin of each adult male rat tested; 300 .mu.L of 14C-benzene alone or with 1 g of clay or sandy soil was introduced under the cap through an opening which was sealed immediately. Pure benzene produced the highest peak plasma concentration of radioactivity, followed closely by sandy soil-adsorbed benzene, with the lowest value exhibited by clay soil-adsorbed benzene. The plasma elimination half-lives were as follows: sandy (24.5 hr), pure (23.0 hr), and clay (19.4 hr). The tissue-concentrations of radioactivity 48 hr post administration were highest in treated skin (covered by the glass cap), followed by the kidney and liver in both soil-treated groups, and were highest in the kidney followed by the liver and treated skin in the pure group. A statistical increase in radioactivity was observed in the treated skin of the clay versus pure group, while a statistical decrease was found in the treated fat (area under skin covered by glass cap) in the same group. Forty-eight-hour studies revealed that radioactivity was excreted primarily in urine and, to a lesser extent, in expired air and in feces for all groups. In all treatments, phenol was the primary metabolite with small amounts of hydroquinone, benzenetriol and catechol detected. These results show that differences in the bioavailability and tissue distribution of benzene occur following dermal exposure to soil-bound versus pure chemical, with the type of soil being an important factor. This information will allow for a more precise estimate of potential health risk following exposure to chemically contaminated soils.