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.

Fig 1. Schematic representation of the trial protocol.

T = time in minutes.

Fig 2. Schematic representation of simulant application sites.

Fig 3. A participant performing improvised dry, improvised wet and the combined decontamination conditions together with representative UV images captured post MeS application and post decontamination.

The red areas of fluorescence on the skin of the participant represent areas of MeS contamination. Area (mid left of images) and emittance (top left, bottom left and mid right of images) MeS calibration disks are also shown.

Fig 4. Area of fluorescence post-decontamination (UV4) for each application site in each decontamination condition.

Box and whisker plot shows median and inter–quartile range, together with the maximum and minimum values. A = Arm, L = Leg, S = Shoulder.

Fig 5. Fluorescent emittance post-decontamination (UV4) for each application site in each decontamination condition.

Box and whisker plot shows median and inter–quartile range, together with the maximum and minimum values. A = arm, L = leg, S = shoulder.

Fig 6. Total MeS recovered in skin samples for each application site in each decontamination condition.

Box and whisker plot shows median and inter–quartile range, together with the maximum and minimum values. A = arm, L = leg, S = shoulder.

Fig 7. Correlation between number of sheets of white roll used as MeS recovered from skin in the dry decontamination condition (B).

r_s = -.614, p = .034.

Fig 8. Total MeS excreted in urine over 24 hours by each participant in each decontamination condition, along with mean and SE in each condition.