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Every inflammatory skin disease with an involvement of the epidermis shows an increased pH. This is true for the group of eczematous diseases, particularly for atopic dermatitis, psoriasis, and ichthyosis. The buffer capacity should be reduced in these diseases; nevertheless, relevant data are still not available. However, in irritant contact dermatitis, there are indirect data for a reduced buffer capacity. The elevated pH observed on the dorsal hand is thought to be a direct consequence of washing. Even the use of water or a mild detergent solution leads to an immediate increase in pH. A stronger increase in pH occurs after washing with an alkaline soap [31]. Repeated contact with water, and in particular with water and detergent, elutes the chemical compounds of the buffer, thereby resulting in a reduced buffer capacity. Therefore, the SC cannot withstand the contact with alkaline compounds including alkaline soap and this may result in dry skin and eczema.

Contact dermatitis of the hands is by far the most important cause for occupational dermatitis. In many occupations, workers have repeated an extensive contact with water, detergents, solvents, and oils. These agents remove protective corneocytes, protective lipids, and protective buffer compounds from the SC. Some people resist these noxious agents well, whereas others may get hand dermatitis, which may even spread over large parts of the body. Many people must give up their occupation because of hand dermatitis, if protective actions are not adhered to adequately. This creates considerable costs for insurances and may leave people unemployed.

To predict which persons are prone to irritation and which are not, test procedures have been developed many years ago. The buffer capacity of the human skin can be determined by titration with an acid or a base and following the changes in the pH with the pH glass electrode [11, 19, 32]. The determination of buffer capacity of the skin with a diluted solution of sodium hydroxide was used in occupational dermatology as a sign whether a patient is prone to irritant contact dermatitis mainly against alkaline compounds like concrete as in the case of construction workers. This was named alkaline resistance or neutralization tests [19]. This test is nowadays in use for special questions only because the test is not reliable for predicting irritant contact dermatitis in general.