Percutaneous Absorption of 2,3,7,8-Tetrachlorodibenzo-P-Dioxin (Tcdd) from Soil (Journal Article)
Eight dermal absorption (two in vivo; six in vitro) and one intravenous experiment were conducted using 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) either neat (high dose at ~250 µg/cm2 and low dose at 10 ng/cm2) or sorbed on a low organic (LOS) or high organic (HOS) soil at 1 ppm (10 ng TCDD/10 mg soil/cm2). After 96 hours the percent of applied dose absorbed (PADA) for the neat low dose was 78% in vivo (rat) and 76% in vitro (rat). PADAs for the equivalent TCDD dose sorbed on LOS were 16.3% (rat-in vivo), 7.7% (rat-in vitro) and 2.4 % (human-in vitro). The PADA for TCDD sorbed on HOS (1 ppm) was 1.0% (rat-in vitro). Generally, rat skin was observed to be 3-4 times more permeable to TCDD than human skin. At steady-state, the dermal flux of TCDD in neat form, on LOS at 1 ppm) and on HOS at 1 ppm (all in vitro-rat) was 120, 0.007 and 0.0007 ng/cm2/hr, respectively (ratio = 1.7x105:10:1. Making adjustments to account for differences between in vitro and in vivo results and adjusting for application to monolayer loads, the 24 hour TCDD absorption for human skin is estimated as 1.9% from LOS (1 ppm) and 0.24% from HOS (1 ppm). Disclaimer: This paper reflects the views of the authors and does not necessarily reflect the views of the Environmental Protection Agency and no official endorsement should be inferred. The mention of trade names or commercial products constitutes neither endorsement nor recommendation of use.