A shower decontamination bench model has been used to assess quantitatively the importance of several variables (water pressure and temperature, surfactant concentration in the decontamination fluid, nozzle type, and shower time) on decontamination of nontoxic chemical warfare-agent simulants diethyl malonate and thickened diethyl malonate from pig skin in virro. Diethyl malonate was validated as a simulant for 1,2,2-trimethylpropyI methylphosphonofluoridate (soman) by comparison of the skin penetration and decontamination of radiolabeled diethyl malonate to the radiolabeled phosphonofluoridate in shower decontamination trials of pig skin in uitro. Percutaneous penetration of diethyl malonate was significantly greater than that of the phosphonofluoridate during the 15-min period after application. However, both were <O. 1% of the applied dose. Showering or thickener had no significant effect on the percutaneous penetration of diethyl malonate or the phosphonofluoridate. Most of the phosphonofluoridate removed by showering or scrubbing the skin was inactivated. The quantity of intact 1,2,2-trirnethylpropyI methylphosphonofluoridate that penetrated through the skin was below the detection limit of the enzymatic analysis. There was no statistically significant difference between the phosphonofluoridate and diethyl malonate in efficacy of shower decontamination. The presence of thickener did not have a significant effect on decontamination efficacy. KeyphrPses 0 Shower decontamination-percutaneous absorption, pig skin D Diethyl malonate-percutaneous absorption, pig skin 0 1,2,2-Trimethylpropyl rnethylphosphonoIluoridate-percutaneous absorption, pig skin @ 1984. American phermaceutlcal Assoclath International Equipment Company, Needham Heights. Mass. Silica gel sheet no. 6061; Eastman Organic Chemicals. Rochester. N.Y.