How irritant is water? An overview

Water is a skin irritant which deserves attention because of its ubiquity. During the Vietnam war, soldiers suffered from painful swollen feet, so-cal led tropical immersion foot. In occupational dermatology, the importance of water as a skin irritant is especially appreciated. The irritancy of water has been demonstrated by occlusion experiments; occlusion with either clos ed chambers or water-soaked patches has been shown to produce clinical and histopathological inflammation. Functional damage, as revealed by increased transepidermal water loss, has also been shown. Repeated water exposure wi thout occlusion caused an increase in blood flow on irritated skin; however , clinical evaluation did not show a difference in dryness or scaling. Seve ral mechanisms such as osmolarity, pH, hardness and temperature might accou nt for the irritancy of water. Extraction or dilution of natural moisturizi ng factors in the stratum corneum is another possible explanation. Occlusio n per se also changes the physiology of skin and may trigger the activation of potentially active substances. However, much remains to be done to clar ify the risk factors and mechanisms of water-induced irritation.