Soil Adsorption Alters Bioavailability of Benzene in Dermally Exposed Male Rats

Abstract

The potential for exposure to chemically contaminated soil is a concern for chemical industry and waste 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 microL 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.(ABSTRACT TRUNCATED AT 250 WORDS)

Dermal absorption of environmental contaminants from soil and sediment: a critical review

“…Riviere, 2000; a portion of the results reported in Roy et al, 1998). Skowronski et al (1988Skowronski et al ( , 1989Skowronski et al ( , 1990) used concentrations of benzene, toluene, and m-xylene more than 100 times higher than estimated soil saturation limits (see Table 2). Poet et al (2000bPoet et al ( , 2002 used maximum concentrations of PCE and TCE approximately 4-80 times estimated soil saturation limits.…”

“…Notably, the experiments of Wester et al (1990Wester et al ( , 1992bWester et al ( , 1993aWester et al ( , b, c, 1996 and Mayes et al (2002) using rhesus monkeys in vivo involved protocols that would have allowed substantial sloughing of soil. In many of the other published in vivo studies description of methods is insufficient to permit assessment of continuity of contact (Poiger and Schlatter 1980;Shu et al, 1988;AbdelRahman et al, 1992;Skowronski et al, 1988Skowronski et al, , 1989Skowronski et al, , 1990Yang et al, 1989;Roy et al, 1990a, b;USEPA 1991;Turkall et al, 1994;Kadry et al, 1995;Qiao et al, 1997). An exception is the in vivo human hand immersion protocol used by Poet et al, (2000aPoet et al, ( , b, 2002.…”

“…As discussed above, presentation of results as percent absorbed without discussion of loading conditions is inappropriate. In the majority of the reviewed empirical investigations, absorption was reported as percentage of initial dose applied even though soil loading rates were above monolayer (Poiger and Schlatter 1980;Abdel-Rahman et al, 1989, 2002Shu et al, 1988;Yang et al, 1989;Skowronski et al, 1988Skowronski et al, , 1989Skowronski et al, , 1990Skowronski et al, , 1994Skowronski et al, , 2000USEPA 1991;Turkall et al, 1994;Kadry et al, 1995;Hughes et al, 1995;Qiao et al, 1997;Roy et al, 1998;Poet et al, 2000aPoet et al, , b, 2002Qiao and Riviere, 2000;Mayes et al, 2002;Reifenrath et al, 2002).…”

“…At 48 h the rats were killed, and their livers were digested and analyzed by liquid scintillation counting. Skowronski et al (1988Skowronski et al ( , 1989Skowronski et al ( , 1990; Abdel- ; Abdel-Rahman et al (1992) In Vivo: Rat Three very similar in vivo studies were conducted using male Sprague-Dawley rats with the solvents benzene, toluene, and m-xylene. Two soils described as having organic carbon contents of 4.4% and 1.6% and particle sizes in the 50-500 mm range were employed.…”

“…In contrast only about 50% of phenanthrene could be accounted for in the corresponding experiments. Skowronski et al (1994) In Vitro: Pig In vitro investigations of absorption of phenol were conducted using the same soils as earlier experiments (e.g., Skowronski et al, 1988). Teflon flowthrough diffusion cells were employed with two different receptor fluids: either 6% aqueous solution of Volpo-20 with thimerosal or HEPES-buffered Hanks' balanced salt solution (HHBSS) containing gentimicin sulfate and 10% fetal bovine serum.…”