Efficacy of water-based skin decontamination of occupational chemicals using in vitro human skin models: a systematic review

Comparison of skin decontamination strategies in the initial operational response following chemical exposures

In mass casualty incidents including hazardous chemical skin exposure, decontamination is the primary intervention to avoid systemic uptake of the toxic compound. The protocol needs to be both simple and efficient to enable a rapid response and avoid delay of patient management. In the present study, decontamination strategies included in the initial operational response were evaluated following human skin exposure in vitro to four different contaminants. Results demonstrated that the efficacy of selected decontamination procedures was highly dependent on the chemical contaminant used. Dry removal of the sulfur mustard simulant methyl salicylate prior to wet decontamination was found beneficial compared to wet decontamination alone. Rapidly initiated wet decontamination was more efficient compared to dry and wet removal of the industrial chemical 2-butoxyethanol and the nerve agent tabun. Following VX-exposure, all wet decontamination procedures resulted in increased agent penetration compared to the control. In conclusion, challenges in establishing simple and efficient decontamination procedures for a broad-spectrum of chemicals have been demonstrated. The impact of including a dry removal step during decontamination was evidently agent specific. Despite the variation in efficacy, immediately initiated dry removal may facilitate patient management until wet decontamination resources are available and to reduce the risk of secondary contamination.

The wash-in effect and its significance for mass casualty decontamination

Decontamination of skin by washing may increase dermal absorption, a phenomenon known as the wash-in effect. The wash-in effect is frequently discussed in studies investigating casualty decontamination where potentially life-saving interventions may enhance the dermal penetration of toxic chemicals, leading to an increase in incidence of morbidity and rates of mortality. However, the wash-in effect is seldom investigated within the context of mass casualty decontamination and real-life consequences are therefore poorly understood. This paper reviews the existing literature on the wash-in effect to highlight the proposed mechanisms for enhanced absorption and evaluate the wash-in effect within the context of mass casualty chemical decontamination.

A Review of the Efficacy of Easily Accessible Dry Decontaminants for Human Chemical Contamination

Soap and water are often considered the gold standard for dermal decontamination. However, recent systematic reviews have shown that these methods often result in incomplete decontamination and may even induce contaminant absorption due to the "wash-in" effect. Therefore, it is important to gain insight on other decontamination methods. A literature search was done using PubMed to find experimental studies relating to dry decontamination performed with readily available items. Seven studies met eligibility criteria, and the study model, dry decontaminant, method of dry decontamination, method of analyzing decontamination, and main conclusions from each study were extracted, summarized and compared. Important conclusions include that all studies investigated found that dry decontamination yielded decreases in contamination. In addition, it was shown by multiple studies that not only the decontaminant, but the manner in which it is used (method used (blotting, rubbing, etc.), amount used, and whether decontamination instructions are provided to exposed individuals) is vital to success. Finally, in all four studies that investigated wet and dry decontamination combination protocols, combinations were more efficacious than dry decontamination alone. However, this means that dry improvised decontamination can be performed while waiting for the deployment and arrival of further formal decontaminants. These conclusions deserve consideration in the event that universal decontamination guidelines are designed. However, more studies are required in order to draw definitive conclusions regarding the important topic of dermal decontamination.

Efficacy of soap and water-based skin decontamination using in vitro animal models: A systematic review

Water and/or soap and water solutions have historically been used as first-line decontamination strategies for a wide variety of dermal contaminants from workplace exposure, environmental pesticides, and civilian chemical warfare. Although water and/or soap and water solutions are often considered a gold standard of decontamination, many studies have found other decontamination methods to be superior. This systematic review summarizes the available data on in vitro animal models contaminated with a various chemicals and their decontamination with water and/or soap and water solutions using in vitro animal models. A comprehensive literature search was performed using Concordance, Embase, PubMed, Medline, Web of Science, and Google Scholar to find in vitro animal studies that provided data on dermal decontamination using water and/or soap and water solutions. Five studies were included that analyzed 11 contaminants across two in vitro animal models (rats and pigs). Water alone was used as a decontamination method for 63.6% of the contaminants (n = 7/11) and water and soap solutions for decontamination in 54.6% of contaminants (n = 6/11). Water alone provided incomplete contaminant removal of five of seven contaminants studied; soap and water did not show significant difference in decontamination when compared with other solutions for all four contaminants and was superior to water for both contaminants studied. Water and/or soap and water are used as decontamination strategies for a variety of dermal contamination events, but for many contaminants, they do not provide complete contamination when compared with newer decontamination solutions studied with in vitro animal models.

Do cold weather temperatures affect the efficacy of skin decontamination?

Skin decontamination in cold weather temperatures might be challenging due to the aggravating circumstances. However, no information is available on the efficacy of commonly used procedures in winter conditions. Therefore, the efficacy of the reactive skin decontamination lotion (RSDL) and soapy water decontamination following skin exposure to the nerve agent VX was evaluated at three ambient air temperatures (-5°C, -15°C and room temperature). Experiments were performed in vitro using human dermatomed skin. The ability of RSDL to degrade VX at the three different air temperatures was separately evaluated. The ambient air temperature in experiments without decontamination did not influence the penetration rate of VX through skin. RSDL decontamination was highly efficient in removing VX from skin when performed in all three ambient temperatures, despite the slower agent degradation rate of VX at the lower temperatures. Decontamination with soapy water at RT resulted in an increased skin penetration of VX compared with the control without decontamination; however, in colder temperatures the VX skin penetration was similar to the corresponding control without decontamination. At RT, dry removal prior to washing with soapy water did not improve decontamination of VX compared with washing solely with soapy water. This study demonstrated high efficacy of RSDL decontamination following skin exposure to VX also at cold temperatures. The previously reported 'wash-in' effect of soapy water on VX skin penetration was reduced at cold temperatures. Altogether, this study found a scientific basis to establish guidelines for skin decontamination of chemical casualties at cold weather temperatures.