Michael Wade

Polychlorinated biphenyls (PCBs) are ubiquitous and persistent environmental pollutants. The major resident site for these PCBs is the soil, and human skin is frequently in contact with soil. Our objective was to determine the percutaneous absorption of the PCBs Aroclor 1242 and Aroclor 1254 from soil. PCB-contaminated soil was prepared at levels of 44 ppm Aroclor 1242 and 23 ppm Aroclor 1254. PCB concentrations on skin were 1.75 micrograms/cm2 for Aroclor 1242 and 0.91 microgram/cm2 for Aroclor 1254. In vivo percutaneous absorption in the rhesus monkey was determined by urinary and fecal [14C]-PCB excretion for a 5-wk period following topical dosing. Absorption of Aroclor 1242 was determined in vitro with human skin for comparative purposes. In vivo in the rhesus monkey the percutaneous absorption of Aroclor 1242 was 13.8 +/- 2.7 (SD)% of the dose and the absorption of Aroclor 1254 was 14.1 +/- 1.0%. These absorption amounts are similar to the absorption of Aroclor 1242 and 1254 from other vehicles (mineral oil, trichlorobenzene, acetone). With in vitro percutaneous absorption through human skin, most of the Aroclor 1242 and Aroclor 1254 resided in the skin and the amounts were dependent upon dosing vehicle (water > mineral oil > soil). Both PCBs readily partitioned from water into soil and human powdered stratum corneum. By difference the partitioning favored both PCBs going from soil into stratum corneum. These data emphasize the role of soil in percutaneous absorption and provide information for appropriate risk assessment.