A controlled cross-over study to evaluate the efficacy of improvised dry and wet emergency decontamination protocols for chemical incidents

Abstract

The UK Initial Operational Response (IOR) to chemical incidents includes improvised decontamination procedures, which use readily available materials to rapidly reduce risk to potentially exposed persons. A controlled, cross-over human volunteer study was conducted to investigate the effectiveness of improvised dry and wet decontamination procedures on skin, both alone, and in sequence. A simulant contaminant, methyl salicylate (MeS) in vegetable oil with a fluorophore was applied to three locations (shoulder, leg, arm). Participants then received no decontamination (control) or attempted to remove the simulant using one of three improvised protocols (dry decontamination; wet decontamination; combined dry and wet decontamination). Simulant remaining on the skin following decontamination was quantified using both Gas Chromatography Tandem Mass Spectrometry (GC-MSMS) for analysis of MeS and UV imaging to detect fluorophores. Additionally, urine samples were collected for 24 hours following application for analysis of MeS. Significantly less simulant was recovered from skin following each improvised decontamination protocol, compared to the no decontamination control. Further, combined dry and wet decontamination resulted in lower recovery of simulant when compared to either dry or wet decontamination alone. Irrespective of decontamination protocol, significantly more simulant remained on the shoulders compared to either the arms or legs, suggesting that improvised decontamination procedures are less effective for difficult to reach areas of the body. There was no effect of decontamination on excreted MeS in urine over 24 hours. Overall, findings indicate that improvised decontamination is an effective means of rapidly removing contaminants from skin, and combinations of improvised approaches can increase effectiveness in the early stages of decontamination and in the absence of specialist resources at an incident scene. However, the variable control and consistency of improvised decontamination techniques means that further intervention is likely to be needed, particularly for less accessible areas of the body.

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

“…However, all decontamination methods were highly effective at reducing the presence of simulant on the scalp. These data are consistent with the high efficacy observed for the same decontamination methods used on human skin 13 however, it remains unclear if this observation was a direct result of removing simulant from the scalp skin or an indirect effect of removing simulant from the hair. Further studies are required to provide clarity but nonetheless this finding could have potential implications for the management of contaminated persons.…”

“…A pragmatic decision not to include improvised wet decontamination in study 2 was made following feedback from UK First Responders that dry decontamination would be the default initial decontamination step for hair during a chemical incident. www.nature.com/scientificreports/ A power calculation using data from a previous trial of improvised and interim decontamination protocols on the removal of a chemical simulant from the skin of human volunteers 13 , determined that a sample size of 12 was sufficient to detect effects under the experimental conditions (power = 0.823). The sample size also allowed contingency in the event of drop-outs or missing data.…”

“…A power calculation using data from a previous trial of improvised and interim decontamination protocols on the removal of a chemical simulant from the skin of human volunteers 13 , determined that a sample size of 12 was sufficient to detect effects under the experimental conditions (power = 0.823). The sample size also allowed contingency in the event of drop-outs or missing data.…”

“…To develop clear and actionable guidance for first responders, acute healthcare receivers and the public, decontamination interventions should be evidence-based. Traditionally this evidence has been generated by evaluating decontamination interventions using in vitro skin diffusion models [2][3][4][5][6][7][8][9][10] or using human volunteers exposed to non-toxic chemical simulants that mimic the properties of chemical agents of concern [10][11][12][13] . To date most studies have evaluated the removal of chemical simulants from the skin only.…”

“…https://doi.org/10.1038/s41598-020-77930-1 www.nature.com/scientificreports/ Simulant application: Two chemical simulants were applied directly to the hair of participants. Simulant one consisted of a 1:1 mix of MeS (99.9%, Fisher Scientific, UK) and vegetable oil (The Cooperative, UK, added to increase persistence)13 and 4 mg/ml Invisible Red S (IRS, Chemox Pound Ltd.). Simulant two consisted of benzyl salicylate (99.9%, Fisher Scientific, UK) with 4 mg/ml Invisible Green S (IGS).…”