Percutaneous Absorption of Pentachlorophenol from Soil

Pentachlorophenol (PCP) is one of the most heavily used pesticides.About 80% of PCP is used for wood preservation, whereas theremainder is used as an herbicide, fungicide, and disinfectant.PCP is a probable human carcinogen, based on animal studies.Illness and death have been reported where PCP is in directcontact with skin. PCP is the most ubiquitous compound foundwhen the general population is screened for pesticide residue.PCP is found in soil as well as other environmental sources.Our objective was to determine the skin bioavailability of PCPfrom soil and from the control vehicle acetone. In vivo in theRhesus monkey, percutaneous absorption of PCP was 24.4±6.4%of applied dose from soil and 29.2±5.8% of applied dosefrom acetone vehicle for a 24-hr exposure period. This amountof absorption makes PCP one of the more extensively absorbedcompounds to date. Additionally, the ¹⁴C half-life was 4.5 daysfollowing both intravenous and skin administration of [¹⁴C]PCP.These data suggest high bioavailability and an extended biologicalinteraction period with the long half-life. In vitro percutaneousabsorption with human cadaver skin and human plasma receptorfluid underestimated the in vivo absorption. Receptor fluidaccumulation was 0.6±0.09% and 1.5±0.2% for twoskin sources for PCP in acetone vehicle and 0.01±0.00%and 0.00±0.08% for two skin sources with soil vehicle.Skin content after skin surface wash ranged from 2.6 to 3.7%for acetone vehicle and 0.07–0.11% for soil vehicle. Overallaccountability for in vitro dose ranged from 81 to 96%.