In vitro permeability and binding of hydrocarbons in pig ear and human abdominal skin

Human skin has continual exposure to chemicals due to various occupational activities. Chemicals that get on skin have the potential to be absorbed. Hence, the potential human health hazards of a chemical must include an estimate for percutaneous absorption. An inexpensive, easy, and adequate model for the quantitative measurement of skin penetration of chemicals from JP-8 is absent. Cutaneous penetration studies in vitro through human skin are severely limited due to the lack of availability of the human skin. In this study, we have shown that pig ear skin can be used as a model for risk assessment from the percutaneous absorption of chemicals. We determined flux and permeability coefficient (Kp) of three chemicals--heptane, hexadecane, and xylene--from their permeation profile through porcine and human skin. Binding of these chemicals to porcine stratum corneum (SC) and human SC were also determined. Factors of difference (FOD) in the permeability of pig and human skin were 1.71, 1.28, and 1.16, respectively, for heptane, hexadecane, and xylene. FOD in binding of heptane, hexadecane, and xylene to pig and human SC were found to be 1.04, 0.76, and 1.31, respectively. Since, FOD for permeability and binding parameters were less than 2, hence, we conclude that pig ear skin can be used as model for humans for risk assessment from percutaneous absorption of chemicals.