Introduction Transepidermal water loss (TEWL) is an objective measurement of skin integrity measured as the amount of water lost across the stratum corneum. TEWL varies greatly across variables such as age and anatomic location, and disruptions in the skin barrier have been linked to inflammatory dermatoses such as psoriasis and atopic dermatitis. Impact of environmental conditions and pollution on TEWL has yet to be determined. Accordingly, this review summarizes effects of environmental conditions and pollution on TEWL. Methods A comprehensive literature search was performed using Embase, PubMed, and Web of Science to find human studies that provided data on environmental conditions and/or pollution and TEWL. Results In total, 15 studies were included, with 11 studies examining environmental and seasonal conditions on TEWL and four examining pollution. All studies examining pollution showed increased TEWL in people exposed to particulate matter or NO2. Contradictory results were found on the effects of season and climate across the 11 studies, with no consensus reached. Conclusion Exposure to pollution is reported to cause increases in TEWL, likely through free radical damage. Significant discrepancies exist among current literature as to the effects of season and climate on TEWL. There is a need to continue examining environmental variables other than temperature and relative humidity, such as atmospheric and steam pressure, that may impact TEWL.

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Water-only or water and soap are widely recommended as preferred solutions for dermal decontamination. However, limited efficacy data exist. We summarized experimental studies evaluating in vitro efficacy of water-only or soap and water in decontaminating chemical warfare agents (CWA) or their simulants from human skin models. Embase, Covidence ® , MEDLINE, PubMed, Web of Science, and Google Scholar were searched for articles using water-only or soap and water decontamination methods for removal of CWA/CWA simulants in in vitro human skin models.Data extraction was completed from seven studies, yielding seven contaminants.Water-only decontamination led to partial decontamination in all skin samples (100%, n = 81/81). Soap and water decontamination led to partial decontamination in all skin samples (100%, n = 143/143). Four studies found decontamination to either paradoxically enhance absorption of contaminants or their penetration rates, known as the "wash-in" effect. Despite recommendations, water-only or water and soap decontamination were found to yield partial decontamination of CWA or their simulants in all human in vitro studies. Thus, more effective decontaminating agents are needed. Some studies demonstrated increased or faster penetration of chemicals following decontamination, which could prove deadly for agents such as VX, although these findings require in vivo validation. Heterogeneity in experimental setups limits interstudy comparison, and it remains unclear when water-only or water and soap are ideal decontaminants, which requires more studies. Pending manuscripts will summarize in vivo human and animal efficacy data. International harmonized efficacy protocol should enable more efficient public health decisions for evidence-based public health decisions.

An optimal amount of water, especially in the stratum corneum, is essential for maintaining normal functioning, healthy skin. 1 Therefore, the amount of water from the skin is carefully regulated, in part through trans-epidermal water loss. 1 Trans-epidermal water loss (TEWL) is an objective measurement of the amount of water passively evaporating from a designated area of stratum corneum in a fixed amount of time due to the water vapour pressure gradient on either side of the skin. It has historically been used as a measure of barrier water function and skin integrity in healthy individuals. 2 Advantages of using a non-invasive marker of skin integrity such as TEWL include a lack of skin barrier destruction, and the potential for early detection of subclinical effects. 3 Elevated TEWL values may reflect barrier dysfunction in diseases such as atopic dermatitis and psoriasis. 4,5 Oppositely, decreased TEWL values reflect an intact or recovered dermal barrier. 5 Thus, TEWL values are typically measured for in vitro permeation testing (IVPT) to reflect a healthy skin sample, and regulatory agencies such as the Food and Drug Administration (FDA) and European Group for Efficacy

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.

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