In vitro percutaneous absorption of sodium arsenate in B6C3F(1) mice

We report the investigation of the percutaneous absorption of sodium [(73)As]arsenate through skin of female B6C3F(1) mice under various conditions of exposure. In vitro diffusion experiments were conducted for 24 hr using previously clipped full-thickness dorsal skin in a flow-through system with HEPES-buffered Hanks' balanced salt solution as the receptor fluid. Doses of 5, 50, 500 or 5000 ng were applied to the skin surface (area = 0.64 cm(2)) as the solid compound, in aqueous vehicle (100 and 250 mul) or in soil (23 mg/cm(2)). Dermal absorption was quantified by summing the amounts of arsenate-derived radioactivity in the receptor fluid and skin following washing of the skin surface to remove unpenetrated compound. Absorption of sodium arsenate increased linearly with the applied dose from all exposure vehicles, with a constant fraction of the dose being absorbed. Maximum absorption (62% of the applied dose) was obtained from the 100-mul aqueous vehicle and the skin contained a higher level of the compound than the receptor fluid. Soil provided the least (<0.3% of the applied dose) absorption of the chemical, with the major portion (68%) of the absorbed dose residing within the skin. Even short-term (1 hr) dermal exposure to arsenate in water resulted in the passage of the chemical into the skin, which, on further perfusion (23 hr), passed into the receptor fluid. Thus, the exposure vehicle plays an important role in the in vitro dermal absorption of sodium arsenate in B6C3F(1) mice, with the aqueous vehicle providing greater absorption than the soil.