Those whose occupations involve extensive soaping of the skin, such as dishwashers, housewives, laundresses and surgeons, clinically show dehydrationor shrivelling of the keratin layers, which leads to irriation of the "primary irritant" type. Patch tests with 2% soap solution theoretically can pick up a true allergy, but I am unconvinced. Perhaps coconut-oil-containing soap are wourse than others. Neutral soaps, such as Lowila, Basis, Oilatum, Hazeline or Dermaphyllic are much less drying. Many of the stronger antibacterial soaps, such as Dial, Zest, Lifebuoy, Safeguard and Palmolive Gold, are sensitizing as well as drying, and may be photosensitizing.
Contact with clothing washed in strong soaps or detergents (e.g., sheets used by bed patients) can lead to dermatitis. This is especially true if bleach or whitener is used. the great offenders in this regard are Axion, Bold, Ajax Detergent, cold Power, Salveo Tabs, Coldwater All, Amway, Arm & Hammer, Era and Dynamo.
Fair-skinned, sensitive or elderly people who bathe a lot in hot showers or tubs can develop an asteatotic eczema that can be extremely intractable. Remembering that the skin's pH is acidic, around 5.0, and all water is slightly alkaline, especially if there are many calcium and magnesium salts in it, it is easy to see how this happens. Cessation of bathing and showering for a while is necessary to clear the skin of these unfortunate patients. An alkaline skin is increasingly susceptible to the irritant effects of water alone, and the hyperirritability of the skin can be protracted; it takes 3 months for a fracture to heal, similarly with the skin. The skin must be put at rest and allowed lubrication for that length of time before it recovers.
The usual result of continuous and excessive exposure of the skin to soaps and detergents is impaired alkaline- neutralization with drying, fisssuring and defatting of the keratin layer leading ot increased permeability of comparatively innocuous substances (e.g., vegetable juices) can lead to senstitization with resultant allergic contact dermatitis subsequent to the original primary irritant effect. It can be almost self-sustaining, and many laundry soaps contain chemical additives which are the actual irritants (e.g., sodium silicate, sodium phosphate, sodium carbonate). Hand cleaner soaps contain small harsh particles to assist in grease removal, such as pumice, talc, borax, corn meal or wood fluor. These are sometimes irritating. Some yellow laundry soaps contain "rosin" to make the bar more soluble, which is also a sensitizer.