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Common Skin Irritants That Cause Hand Eczema
Repeated hand washing can lead to dryness
An irritant is any agent, physical or chemical, which is capable of producing cell damage, if applied for sufficient time and in sufficient concentration. Skin irritants induce damage by gradually exhausting the uppermost horny layer (Stratum corneum), denaturing the keratin, removing skin surface lipids, and altering the water holding capacity of skin. This eventually causes damage to the living cells of epidermis. The common everyday use substances that can cause skin irritation and eczema on hands, include the following:
Cleaning and wet work dissolve hygroscpic substances needed to maintain skin integrity
Wet work is an essential part of many occupations. Water is hypotonic (has low osmolarity)and has a damaging effect on previously eroded skin. If the surface lipid film of skin has been removed previously by detergents, water may dissolve the hygroscopic substances (that have the capacity to retain moisture) needed to maintain skin integrity. Lime, magnesium and iron from hard water can get deposited on the skin and lead to mechanical irritation. Skin irritation may also occur from poorly controlled chlorination or bromination of swimming and spa pools.
2. Skin cleansers
Soaps, detergents and water less cleansers containing organic solvents are the commonest causes of an irritant reaction. They raise the skin pH from acidic to alkaline, and dissolve natural moisturizing factors. Added silica (as small balls) or sand tend to cause damage by mechanical abrasion. In many occupations like metal industries, the procedures used for hand cleaning may be more harmful to the skin than the work itself. Aromatic compounds in water less cleansers are also hazardous.
Detergents contain chemicals that destroy the surface protective lipid film of skin
3. Detergents, wetting agents and emulsifiers
Washing powders contain detergents, perborates, phosphates, optical bleaches and perfume. Some also have added soap, and chelating agents to prevent precipitation of calcium salts. Most detergents are alkaline, but even at a neutral pH, they remove the surface protective lipid layer, certain water holding substances and vital fats from the uppermost layer of skin. They denature skin proteins and damage the cell membranes.
These are used in industries, for example, chromic acid for rust-proofing iron, and hydroflouric acid for glass etching, rust stain removal, electronics, and petroleum industry. Acids are very harsh on skin, can cause severe damage and irritant dermatitis.
The major offenders are metal working fluids, which may be neat oils, oil-in-water emulsions (soluble oils), the semi-synthetic or synthetic ones.
Alkaline substances such as chalk can cause skin damage
Alkaline substances such as soap, soda, ammonia, potassium and sodium hydroxide, cement, chalk, sodium silicate and hardeners saponify the skin surface lipids, dissolve the water holding substances, break the cross linkage of keratin, and cause swelling of cells. Soda ash is three times stronger and more damaging than washing soda.
7. Organic solvents
These include white spirit, prime-grade kerosene, diesel oil, fuel oil, thinners (for cleaning textiles and metals, graphic industries, floor laying, wood furnishing, dyeing, painting etc and as solvents in polishes and disinfectants). Organic solvents can lead to skin allergy and eczema.
8. Oxidizing agents
These include benzoyl peroxide, cyclohexanone peroxide used in hardening polyester resins, hair bleaches, for bleaching textiles, oils, and flour; sodium hypochlorite used for cleaning and to remove stains from their hands by printers and dyers. Ethylene oxide used as a sterilizing agent may remain on surgical instruments and rubber goods and can cause skin irritation.
9. Plants and wood
Citrus peel, flower bulbs, garlic flour, wood dust, spices, corn, onion, pineapple, pelargonium, iris, stinking mayweed, buttercup, daffodil, and plants of mustard family, can act as irritants. Sharp barley awns can cause eruptions, itching and mechanical damage to the skin.
10. Animal products
Caterpillars, carpet beetles and moths can cause irritant reactions. Wet work with fish, shrimps, meat and herring in canning industries or restaurants can have such effects.
11. Topical medicaments
In susceptible individuals, tar, dithranol, potassium permanganate and gentian violet can, even in low concentrations, lead to overtreatment dermatitis, which also occurs after prolonged use of wet dressings.
This is present in trees of the Pinaceae family, as for example pine and spruce. Their sawdust can cause sensitization. Colophony may be present in varnishes, finishes, modified pheno-plastic, glue, violin resin, rubber, soap, soldering flux, waxes, polish for furniture, floors and cars, in printer's ink, chewing gum, and wart gels. It is also used on fanbelts and in clutches for extra grip.Adhesive tape contains this resin, and is the commonest source of skin sensitization.
Updated 23-12-2014 : Bleaches are strong cytotoxic agents. They denature proteins and damage cell membranes of skin cells of uppermost layer of skin. Initially this presents as dryness and chapping. But in the long run, and with repeated exposure to harsh chemicals, eczematous lesions begin to develop.