PRELIMINARY EVALUATION OF NOVEL SURFACTANT-BASED DECONTAMINANTS FOR SKIN EXPOSURE TO PHORATE: A SIMULANT OF THE VX NERVE AGENT.

Effective skin decontamination is critical during mass-casualty incidents involving organophosphorus nerve agents, where dermal exposure and persistence can drive morbidity. We performed a preliminary in vitro evaluation of two novel surfactant-based formulations (University of Alcalá) intended for shower-based decontamination following VX exposure, using ¹⁴C-phorate as a safer physicochemical simulant. Experiments followed OECD Test Guideline 428 using static Franz-type diffusion cells with dermatomed porcine skin. A 10 µL droplet of ¹⁴C-phorate was applied to the skin, and decontamination was initiated 60 min post-exposure using an ORCHIDS-style protocol: (i) no decontamination (control); (ii) warm water shower (90 s); (iii) 0.5% v/v Formulation 1 (1 min) + water rinse (30 s); or (iv) 0.5% v/v Formulation 2 (1 min) + water rinse (30 s). Each protocol was followed by active drying with a microfibre cloth (n = 6 diffusion cells/group). Radioactivity was quantified by liquid scintillation counting in receptor fluid, donor chamber, skin surface, skin, shower effluent, and cloth; autoradiography with ImageJ was used to quantify lateral spreading. Non-parametric statistics used Kruskal–Wallis with Dunn’s multiple comparisons. Both surfactant formulations significantly reduced the bioavailable dose (receptor fluid + skin surface + skin) versus untreated controls, with decontamination efficacies of 93 ± 48% (Formulation 1, p < 0.05) and 96 ± 45% (Formulation 2, p < 0.05), whereas water alone achieved 88 ± 35% and was not significant. Water-only decontamination exhibited a rinse-in (“wash-in”) effect, with approximately doubled simulant penetration into skin versus untreated controls; both surfactant formulations negated this effect. Autoradiography/ImageJ showed that both formulations significantly reduced lateral spreading compared with controls (p < 0.05), whereas water did not. Across the three shower decontamination arms, the largest recovered fraction was consistently captured by the microfibre cloth (~20–40%), underscoring active drying as a key contributor; Formulation 2 yielded ~two-fold higher cloth recovery than Formulation 1, although this difference was not statistically significant. These initial results support further testing of surfactant-based technologies as rapid and effective tools for chemical incident response and highlight their potential for future field deployment.