Research Article: Evaluation of absorbent materials for use as ad hoc dry decontaminants during mass casualty incidents as part of the UK’s Initial Operational Response (IOR)

Date Published: February 2, 2017

Publisher: Public Library of Science

Author(s): Nick Kassouf, Sara Syed, Joanne Larner, Richard Amlôt, Robert P. Chilcott, Chon-Lin Lee.

http://doi.org/10.1371/journal.pone.0170966

Abstract

The UK’s Initial Operational Response (IOR) is a revised process for the medical management of mass casualties potentially contaminated with hazardous materials. A critical element of the IOR is the introduction of immediate, on-scene disrobing and decontamination of casualties to limit the adverse health effects of exposure. Ad hoc cleansing of the skin with dry absorbent materials has previously been identified as a potential means of facilitating emergency decontamination. The purpose of this study was to evaluate the in vitro oil and water absorbency of a range of materials commonly found in the domestic and clinical environments and to determine the effectiveness of a small, but representative selection of such materials in skin decontamination, using an established ex vivo model. Five contaminants were used in the study: methyl salicylate, parathion, diethyl malonate, phorate and potassium cyanide. In vitro measurements of water and oil absorbency did not correlate with ex vivo measurements of skin decontamination. When measured ex vivo, dry decontamination was consistently more effective than a standard wet decontamination method (“rinse-wipe-rinse”) for removing liquid contaminants. However, dry decontamination was ineffective against particulate contamination. Collectively, these data confirm that absorbent materials such as wound dressings and tissue paper provide an effective, generic capability for emergency removal of liquid contaminants from the skin surface, but that wet decontamination should be used for non-liquid contaminants.

Partial Text

Mass casualty incidents arising from the accidental or deliberate release of hazardous materials require a rapid and efficient response from emergency personnel in order to minimise the injurious effects of exposure to toxic materials. Until recently, the UK’s Model Response to chemical, biological, radiological and nuclear, or hazardous material incidents involved delaying disrobing and decontamination until the arrival of specialist response assets, such as mass decontamination units. However, recent work has demonstrated that a more rapid response is required for chemical exposures and that self-decontamination may be performed by contaminated individuals using any available absorbent material [1]. Moreover, there is evidence to suggest that showering contaminated skin with water may lead to the “wash-in effect”—the enhanced dermal absorption of particular chemicals [2–6]. In response to such practical challenges, the UK emergency services have adopted a revised process known as the Initial Operational Response (IOR). This new approach advocates dry decontamination as the default option for an emergency response [7]. A variety of bespoke decontamination products are commercially available and have been previously evaluated in our laboratory [8]. However, such products are not appropriate or practical for use in mass casualty decontamination [9].

This study consisted of two parts. First, 35 materials identified from site visits to an emergency department and ambulance station were assessed using an empirical system that measured the relative capacity of each product to absorb water and oil. Four of the test materials were then selected for evaluation regarding their efficacy in decontamination. For this purpose we used a bespoke ex vivo diffusion cell system containing pig skin, which has previously been described and validated for assessment of skin decontamination systems [17]. The association between the initial absorption capability of each material and its usefulness in decontamination was evaluated retrospectively.

This study demonstrated that absorbent materials commonly found in clinical environments, such as hospitals and ambulances, are generally more effective than the standard R-W-R technique for the decontamination of liquid chemicals from the skin surface. These data are in agreement with previous in vitro, in vivo and human volunteer studies, which indicated that dry decontamination is effective for the removal of liquid chemicals [18]. Moreover, dry decontamination requires considerably less time (<5 s) than does the R-W-R method (90 s). However, the dry decontamination products were ineffective against potassium cyanide, whereas the R-W-R method was highly effective. This disparity is most probably due to the presentation of the contaminant on the skin surface: unlike the other (liquid) contaminants used in this study, potassium cyanide is a solid and so was dissolved in water for topical application. Fifteen minutes after skin exposure (at the time of decontamination), the water was observed to have evaporated, leaving a crystalline deposit on the skin surface. Thus, the experiments with cyanide reflect contamination of the skin with particulate material rather than liquid. Therefore, these data confirm that, whilst dry decontamination should be the default option for skin contaminated with liquid chemicals, aqueous decontamination is required to remove particulate contamination.   Source: http://doi.org/10.1371/journal.pone.0170966

 

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