Hairless guinea pig bioassay model for vesicant vapor exposures.

Sulfur mustard (HD; 1,1'-thiobis[2-chloroethane]) induces fluid-filled blisters in man but not in conventional laboratory animals. An animal model is needed to emulate both cytotoxic (vesicant) and vascular (irritant) responses of human skin to HD exposures. An acceptable model must permit reproducible comparisons of uniformly graded and dose-related HD control responses with reduced responses that may follow antivesicant treatments. Hairless guinea pigs were evaluated by exposing six or eight dorsal skin sites 12 mm in diameter to similar HD vapor concentrations for graded intervals (1-16 min). HD vapor was delivered under occlusive caps holding 10 microliters of HD in filter paper located 5 mm above the skin. Four-minute exposures induced moderate erythema, slight edema, and microblisters in 1 of 39 sites. Eight-minute exposures induced severe erythema, moderate edema, and microblisters in 31 of 40 sites. Gross blistering was not seen after use of vapor cups, but damage to basal cells resembled lesions of vesicant injury in man. The hairless guinea pig model, with graded HD vapor exposures, provides acceptable comparisons of responses. Exposures of both 4- and 8-min durations were used to show the feasibility of using this model to bioassay antivesicant topical protectants. These methods may be useful for measurements of irritant and cytotoxic responses of skin to other toxic vapors.

Chemical hazards and chemical warfare

This report describes chemical disaster situations in which human risk is the overriding consideration. Emphasis is placed on hazards to persons who may deal with contaminated people or animals. Precautions and response designed to reduce some life- threatening consequences of various chemical emergencies are discussed

Evaluation of diethyl malonate as a simulant for 1,2,2-trimethylpropyl methylphosphonofluoridate (soman) in shower decontamination of the skin.

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 vitro. Diethyl malonate was validated as a simulant for 1,2,2-trimethylpropyl 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 vitro. Percutaneous penetration of diethyl malonate was significantly greater than that of the phosphonofluoridate during the 15-min period after application. However, both were less than 0.1% 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-trimethylpropyl 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.

Anti-lewisite activity and stability of meso-dimercaptosuccinic acid and 2,3-dimercapto-1-propanesulfonic acid.

Meso-dimercaptosuccinic acid (DMSA) and the sodium salt of 2,3-dimercapto-1-propanesulfonic acid (DMPS) are analogous in chemical structure to dimercaprol (BAL, British Anti-Lewisite). Dimercaprol was among the first therapeutically useful metal chelating agents and was developed originally as an anti-lewisite agent. Either DMSA or DMPS protects rabbits from the lethal systemic action of dichloro(2-chlorovinyl)arsine (29.7 mumols/kg, also known as lewisite. The analogs are active in this respect when given either sc or po. The stability of each of the three dimercapto compounds in distilled H2O, pH 7.0 at 24 degrees, has been examined for seven days. DMSA retained 82% of its mercapto groups, but no titratable mercapto groups remained in the DMPS or BAL solutions. At pH 5.0, however, there was no striking difference in the stability of the three dimercapto compounds (78-87%) over a seven day period. DMSA and DMPS warrant further investigation as water soluble metal binding agents in both in vivo and in vitro experiments.