A Standard Method for Soil-to-Clothing Contact Transfer of Soil-Sorbed Chemical Agents.

Exposure to chemical warfare agents (CWA) sorbed onto soil can present a potential Contact Hazard. Previous studies have investigated levels of CWA transferred from contaminated surfaces utilizing malleable latex material (dental dam; DD) as transfer substrate; however DD is typically inconsistent in compositions, and not a reliable simulant for toxicological investigations. Measurements of CWA on standard Army Combat Uniform (ACU), plus CWA toxicological effects on mammalian skin (bioavailability), have been reliably established for some CWA, and ongoing-testing continues for others; but need existed for a reliable transfer-exposure method for soil-sorbed CWA. We have established a method for reliably determining Contact Transfer of soil-sorbed compounds directly onto clothing, utilizing standard mass (x Gravity) as a standard force to produce a standard measure of exposure potential. We initially determined effects of contact time and applied mass (DD); benchmark investigations established efficacy of CWA extraction from ACU (and DD), and Contact Transfer of soil-sorbed CWA onto ACU. A 4”-diameter circular swatch of ACU was selected, similar to surface areas that may contact soil at knee or elbow locations; standard contact was created by placing ACU swatch directly onto soil-surface one minute after CWA sorption, then covering swatch with 4”-diameter Plexiglass disk to distribute force from centrally-placed standard mass. Contact Transfer of CWA was determined by solvent extraction of swatches with analyses by GC/GC-MS. Masses 0.250, 0.500, 1.000, 1.500 kg, resulted in significantly greater CWA transfer (p ≤0.05) at ≥0.500kg compared to 0.250kg; 1-kg standard mass selected. Although the quantities of soil-sorbed CWA that transferred increased as a function of contact time, rate of transfer decreased dramatically after 1h; 0.25-h selected. Soil-sorbed CWA transferred at levels within the range of concern for Soldiers; Contact Transfer Method provides reliable standard predictions of exposure potential, and in conjunction with toxicity data for predictions of Contact Hazard.