Development of haemostatic decontaminants for the treatment of wounds contaminated with chemical warfare agents. 2: Evaluation ofin vitrotopical decontamination efficacy using undamaged skin

Skin decontamination of Carfentanil in vitro

Skin decontamination of Chemical Biological Radioactive and Nuclear (CBRN) materials involves the timely and effective removal of the contaminants from the skin surface. The current work evaluated Fuller's Earth & The Reactive Skin Decontaminant Lotion Kit (RSDL®) to investigate whether they were as efficacious against free base Carfentanil skin contamination as they are against chemical warfare agents. The in vitro methodology used allowed for evaluation of decontamination regimens as specified by the decontaminant manufacturer rather than as an application of a bolus dose left in situ for the study duration. A selection of novel decontaminants, including Dermal Decontamination Gel (DDGel), Trivorex®, itaconic acid (IA), N,N'-methylenebisacrylamide (MBA), 2-trifluoromethylacrylic acid (TFMAA) and NanoSan Sorb were also tested for efficacy. All the evaluated decontaminants were successful at removing the majority of the Carfentanil skin surface contamination. The current work has shown that the Fuller's Earth decontamination kit, removes as much (or more) free base carfentanil from the skin surface in comparison to other products tested in this study series.

Human volunteer study of the decontamination of chemically contaminated hair and the consequences for systemic exposure

The decontamination of exposed persons is a priority following the release of toxic chemicals. Efficacious decontamination reduces the risk of harm to those directly affected and prevents the uncontrolled spread of contamination. Human studies examining the effectiveness of emergency decontamination procedures have primarily focused on decontaminating skin, with few examining the decontamination of hair and scalp. We report the outcome of two studies designed to evaluate the efficacy of current United Kingdom (UK) improvised, interim and specialist mass casualty decontamination protocols when conducted in sequence. Decontamination efficacy was evaluated using two chemical simulants, methyl salicylate (MeS) and benzyl salicylate (BeS) applied to and recovered from the hair of volunteers. Twenty-four-hour urinary MeS and BeS were measured as a surrogate for systemic bioavailability. Current UK decontamination methods performed in sequence were partially effective at removing MeS and BeS from hair and underlying scalp. BeS and MeS levels in urine indicated that decontamination had no significant effect on systemic exposure raising important considerations with respect to the speed of decontamination. The decontamination of hair may therefore be challenging for first responders, requiring careful management of exposed persons following decontamination. Further work to extend these studies is required with a broader range of chemical simulants, a larger group of volunteers and at different intervention times.

Hybrid in vitro diffusion cell for simultaneous evaluation of hair and skin decontamination: temporal distribution of chemical contaminants

Most casualty or personnel decontamination studies have focused on removing contaminants from the skin. However, scalp hair and underlying skin are the most likely areas of contamination following airborne exposure to chemicals. The aim of this study was to investigate the interactions of contaminants with scalp hair and underlying skin using a hybrid in vitro diffusion cell model. The in vitro hybrid test system comprised “curtains” of human hair mounted onto sections of excised porcine skin within a modified diffusion cell. The results demonstrated that hair substantially reduced underlying scalp skin contamination and that hair may provide a limited decontamination effect by removing contaminants from the skin surface. This hybrid test system may have application in the development of improved chemical incident response processes through the evaluation of various hair and skin decontamination strategies.

The percutaneous toxicokinetics of VX in a damaged skin porcine model and the evaluation of WoundStat™ as a topical decontaminant

This study used a damaged skin, porcine model to evaluate the in vivo efficacy of WoundStat™ for the decontamination of superficial, nerve agent-contaminated wounds. Anaesthetized animals were randomly assigned to either control (n = 7), no decontamination (n = 12) or WoundStat™ (n = 12) treatment groups. Pigs were exposed to a 5× LD₅₀ dose of neat, radiolabelled S-[2-(diisopropylamino)ethyl]-O-ethyl methyl-phosphonothioate (VX; or equivalent volume of sterile saline for the control group) via an area of superficially damaged skin on the ear. WoundStat™ was applied at 30 seconds post-exposure to assigned animals. The VX contaminant (or saline) and decontaminant remained in place for the duration of the study (up to 6 hours). Physiological parameters and signs of intoxication were recorded during the exposure period. Skin and organ samples were taken post mortem for ¹⁴ C-VX distribution analyses. Blood samples were taken periodically for toxicokinetic and whole-blood acetylcholinesterase (AChE) activity analyses. VX exposure was accompanied by a rapid decrease in AChE activity in all animals, regardless of decontamination. However, decontamination significantly improved survival rate and time and reduced the severity of signs of intoxication. In addition, the distribution of ¹⁴ C-VX in key internal organs and post mortem blood samples was significantly lower in the WoundStat™ treatment group. This study demonstrates that WoundStat™ may be a suitable medical countermeasure for increasing both survival rate and time following VX exposure. The results also suggest that AChE activity is not a useful prognostic indicator.

Layer-by-layer assembly of Cu3(BTC)2 on chitosan non-woven fabrics: a promising haemostatic decontaminant composite material against sulfur mustard

Anchoring Cu₃(BTC)₂ on the surface of chitosan non-woven fabrics results in formation of a new haemostatic decontaminant composite materials.

Mass Casualty Decontamination in a Chemical or Radiological/Nuclear Incident with External Contamination: Guiding Principles and Research Needs

Hazardous chemical, radiological, and nuclear materials threaten public health in scenarios of accidental or intentional release which can lead to external contamination of people.  Without intervention, the contamination could cause severe adverse health effects, through systemic absorption by the contaminated casualties as well as spread of contamination to other people, medical equipment, and facilities.  Timely decontamination can prevent or interrupt absorption into the body and minimize opportunities for spread of the contamination, thereby mitigating the health impact of the incident.  Although the specific physicochemical characteristics of the hazardous material(s) will determine the nature of an incident and its risks, some decontamination and medical challenges and recommended response strategies are common among chemical and radioactive material incidents.  Furthermore, the identity of the hazardous material released may not be known early in an incident.  Therefore, it may be beneficial to compare the evidence and harmonize approaches between chemical and radioactive contamination incidents.  Experts from the Global Health Security Initiative’s Chemical and Radiological/Nuclear Working Groups present here a succinct summary of guiding principles for planning and response based on current best practices, as well as research needs, to address the challenges of managing contaminated casualties in a chemical or radiological/nuclear incident.