Dermal Absorption Kinetics of Liquid Chloropentafluorobenzene (CPFB) and 1,2-Dichlorobenzene (DCB) in Rats and Guinea Pigs.

Abstract : The potential for occupational or accidental skin exposure to chemicals requires a full understanding of chemical absorption through the skin. To determine whether species differences in dermal absorption are due to physical and physiological dissimilarities, male F-344 rats and Hartley guinea pigs were chosen to provide different characteristics in the skin. Two model chemicals Chloropentafluorobenzene (CPFB) and 1,2-Dichlorobenzene (DCB) were chosen to provide a range of volatilities and water and lipid solubilities for in vivo study. Twenty four hours prior to exposure each animal was fitted with a jugular cannula and the glass cell was attached to the animal's back. All the animals were exposed to pure liquid CPFB and DCB for 2 to 4 hours in a 3.14 cm(2), septum sealed glass cell. Blood was serially drawn and analyzed for these chemicals. The blood concentration of the absorbed chemicals peaked during the first 1/2 to 2 hours of exposure and stayed constant or declined up to 4 hours. The decline in blood concentrations suggests that the rate of penetration decreases during the exposure, especially with DCB and the guinea pig. Additionally, in each species with each chemical, the histological/pathological changes in the exposure area of the skin were examined. There was a correlation between the onset of minimal skin damage and the time when the chemical peak value was reached in the blood. These studies suggest that prolonged contact of chemicals with the skin may reduce penetration of some chemicals.