Percutaneous Absorption of 3,3′,4,4′-Tetrachlorobiphenyl (PCB 77) from Soil

Abstract

Six dermal absorption experiments (one in vivo, five in vitro) were conducted using 3,3′,4,4′-tetrachlorobiphenyl (TCB) either neat at 141 μg/cm² or sorbed on a low organic (LOS) or high organic (HOS) soil at 6–10 μg/cm². All soil experiments were conducted at 1000 ppm and soil loads of 6–10 mg soil/cm². After 96 h the percentage of applied dose absorbed (PADA) for TCB sorbed on LOS was 49.7 (rat, in vivo), 31.9 (rat, in vitro), and 7.4 (human, in vitro). The 96-h PADA for TCB sorbed on HOS was 9.6% (rat, in vitro). Generally, rat skin was observed to be four- to ninefold more permeable to TCB than human skin (in vitro). At steady state, the dermal flux of TCB on LOS at 1000 ppm and on HOS at 1000 ppm (both in vitro, rat) was 33 and 10 ng/cm²/h, respectively (ratio = 3.3).

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The authors express their gratitude for the contributions of Joseph Yang and Andrew Krueger, who did much of the original laboratory work supporting this article. The facility conducting the studies was fully accredited by the AAALAC (Association for the Assessment and Accreditation of Laboratory Animal Care International). All protocols were reviewed and approved by the IACUC (Internal Animal Care and Use Committee) at the facility prior to the initiation of studies. Support for this research was received from the U.S. EPA Office of Research and Development.