Percutaneous absorption of 3,3',4,4'-tetrachlorobiphenyl (PCB 77) from soil

Six dermal absorption experiments (one in vivo, five in vitro) were conducted using 3,3',4,4'-tetrachlorobiphenyl (TCB) either neat at 141 microg/cm2 or sorbed on a low organic (LOS) or high organic (HOS) soil at 6-10 microg/cm2. All soil experiments were conducted at 1000 ppm and soil loads of 6-10 mg soil/cm(2). 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).