Toward a better understanding of pesticide dermal absorption: diffusion model analysis of parathion absorption in vitro and in vivo.
J Toxicol Environ Health, A 2010 Jan; 73(4):284-300
Human skin absorption of radiolabeled parathion was studied in vitro at specific doses (mass loadings) of 0.4, 4.0, 41, or 117 µg/cm2, with and without occlusion. The compound was applied in small volumes of acetone solution to split-thickness skin. Permeation of radiolabel into the receptor solutions was monitored for 76 h, after which the tissue was dissected and analyzed for residual radioactivity. For the 3 lower doses, cumulative permeation after 76 h was approximately dose-proportional, ranging from 28.5-30.5% of applied dose (unoccluded) to 45.5-55.7% (occluded). Total absorption, calculated as receptor fluid plus dermis content, followed a similar pattern. Both permeation rate and total absorption continued to increase up to the highest dose tested, consistent with results from other laboratories. These results are compared with predictions from a previously developed skin diffusion model (Kasting et al., 2008a). The model predicted total absorption to within a factor of 1.4 at 0.4 µg/cm2 and 1.6 at 4 µg/cm2, but substantially underpredicted absorption at the 2 higher doses. The analysis showed that parathion partitioned more favorably into the stratum corneum than the diffusion model prediction. Nevertheless, comparison of the model predictions to a previously reported human study showed that the skin absorption model, when corrected for surface losses occurring in vivo, satisfactorily described in vivo dermal absorption of parathion applied at 4 µg/cm2 to various body sites.
Absorption-rates; Chemical-composition; Chemical-properties; Chemical-reactions; Cytology; Dermatology; Diffusion-analysis; Exposure-assessment; Exposure-levels; Exposure-methods; Humans; Laboratory-testing; Pesticides; Pesticides-and-agricultural-chemicals; Skin; Skin-absorption; Skin-exposure; Statistical-analysis; Surface-properties
Gerald B. Kasting, James L. Winkle College of Pharmacy, University of Cincinnati Academic Health Center, P.O. Box 670004, Cincinnati, OH 45267-0004
Research Tools and Approaches: Exposure Assessment Methods
Journal of Toxicology and Environmental Health, Part A: Current Issues
University of Cincinnati