Christopher Dalton
Defence Science and Technology Laboratory, UK
Title: Effect of exposure area on nerve agent absorption through skin in vitro
Biography
Biography: Christopher Dalton
Abstract
Diffusion cells are used to determine the penetration of chemicals through skin in vitro. The cells have a limited surface area defined by the edge of the donor chamber. Should the penetrant spread rapidly to this containment limit the penetration rate can be accurately quantifi ed. For the hazard assessment of small droplets of toxic chemicals, such as cholinesterase inhibitors, limiting skin surface spread in vitro could lead to underestimation of percutaneous penetration and hence underestimation of systemic toxicity in vivo. The current study investigated the dependency of the percutaneous penetration of undiluted radiolabelled nerve agents [VX and soman (GD), 10μl] on skin surface spread (pig and guinea pig) using Franz-type glass diffusion cells with an area available for diffusion of either 2.54 cm2 or 14.87 cm2. Both VX and GD spread to the edge of 2.54 cm² cells, but not to the 14.87 cm² cells over the study duration. Amounts of VX and GD penetrating pig and guinea pig skin
in the 2.54 cm² cell were less than in the 14.87 cm² cell (except for GD under unoccluded conditions), however, penetration rates expressed per unit area were similar. Artificial limitation of skin surface spread in vitro does not impact percutaneous penetration in vitro as long as penetration is expressed in terms of mass per unit area.
