Irritant contact dermatitis
Encyclopedia
Irritant contact dermatitis is a form of contact dermatitis
Contact dermatitis
Contact dermatitis is a term for a skin reaction resulting from exposure to allergens or irritants . Phototoxic dermatitis occurs when the allergen or irritant is activated by sunlight....

 that can be divided into forms caused by chemical irritants and those caused by physical irritants.

Chemical irritant contact dermatitis

Chemical irritant contact dermatitis is either acute or chronic, which is usually associated with strong and weak irritants respectively (HSE MS24). The following definition is provided by Mathias and Maibach (1978): The mechanism of action
Mechanism of action
In pharmacology, the term mechanism of action refers to the specific biochemical interaction through which a drug substance produces its pharmacological effect...

 varies between toxins. Detergents, surfactants, extremes of pH, and organic solvents all have the common effect of directly affecting the barrier properties of the epidermis. These effects include removing fat emulsion, defatting
Defatting (medical)
Defatting is a medical term that describes the chemical dissolving of dermal lipids, from the skin, on contact with defatting agents. This can result in water loss from the affected area and cause the whitening and drying of the skin which may result in cracking, secondary infection and chemical...

 of dermal lipids, inflicting cellular damage on the epithelium, and increasing the transepidermal water loss
Transepidermal water loss
Transepidermal Water Loss or is a term associated with dermatology and connected sciences.It is defined as the measurement of the quantity of water that passes from inside a body through the epidermal layer to the surrounding atmosphere via diffusion and evaporation processes.Transepidermal...

 by damaging the horny layer water-binding mechanisms and damaging the DNA, which causes the layer to thin. Strong concentrations of irritants cause an acute effect, but this is not as common as the accumulative, chronic effect of irritants whose deleterious effects build up with subsequent doses (ESCD 2006).

Common chemical irritants implicated include solvents (alcohol, xylene
Xylene
Xylene encompasses three isomers of dimethylbenzene. The isomers are distinguished by the designations ortho- , meta- , and para- , which specify to which carbon atoms the two methyl groups are attached...

, turpentine
Turpentine
Turpentine is a fluid obtained by the distillation of resin obtained from trees, mainly pine trees. It is composed of terpenes, mainly the monoterpenes alpha-pinene and beta-pinene...

, esters, acetone
Acetone
Acetone is the organic compound with the formula 2CO, a colorless, mobile, flammable liquid, the simplest example of the ketones.Acetone is miscible with water and serves as an important solvent in its own right, typically as the solvent of choice for cleaning purposes in the laboratory...

, ketones, and others); metalworking fluids (neat oils, water-based metalworking fluids with surfactants); latex; kerosene
Kerosene
Kerosene, sometimes spelled kerosine in scientific and industrial usage, also known as paraffin or paraffin oil in the United Kingdom, Hong Kong, Ireland and South Africa, is a combustible hydrocarbon liquid. The name is derived from Greek keros...

; ethylene oxide
Ethylene oxide
Ethylene oxide, also called oxirane, is the organic compound with the formula . It is a cyclic ether. This means that it is composed of two alkyl groups attached to an oxygen atom in a cyclic shape . This colorless flammable gas with a faintly sweet odor is the simplest epoxide, a three-membered...

; surfactants in topical medications and cosmetics (sodium lauryl sulfate); alkalies (drain cleaners, strong soap with lye
Lye
Lye is a corrosive alkaline substance, commonly sodium hydroxide or historically potassium hydroxide . Previously, lye was among the many different alkalis leached from hardwood ashes...

 residues).

Physical irritant contact dermatitis

Physical irritant contact dermatitis is a less researched form of ICD (Maurice-Jones et al.) due to its various mechanisms of action and a lack of a test for its diagnosis. A complete patient history combined with negative allergic patch testing is usually necessary to reach a correct diagnosis. The simplest form of PICD results from prolonged rubbing, although the diversity of implicated irritants is far wider. Examples include paper friction, fiberglass, and scratchy clothing.

Low humidity

In a recent analysis of patient data, low humidity from air conditioning
Air conditioning
An air conditioner is a home appliance, system, or mechanism designed to dehumidify and extract heat from an area. The cooling is done using a simple refrigeration cycle...

 was found to be the most common cause of PICD (Morris-Jones, Rachael et al.) To the lay person a definition of low humidity being a physical irritant can be confusing because low humidity is a deficit (or absence) of an elemental substance, whereas ALL other irritants implicated in contact dermatitis are in concentrations of relative abundance. So the irritant is actually a lack of another substance, namely water vapour. This confusion is further compounded with the use of the term contact implying 'touching' (as is the case with all other forms of PICD) whereas in the case of low humidity PICD there is an absence of contact with water vapour.

Plants

Many plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...

s cause ICD by directly irritating the skin. Some plants act through their spines or irritant hairs. Some plant such as the buttercup, spurge
Spurge
Euphorbia is a genus of plants belonging to the family Euphorbiaceae. Consisting of 2008 species, Euphorbia is one of the most diverse genera in the plant kingdom, exceeded possibly only by Senecio. Members of the family and genus are sometimes referred to as Spurges...

, and daisy
Asteraceae
The Asteraceae or Compositae , is an exceedingly large and widespread family of vascular plants. The group has more than 22,750 currently accepted species, spread across 1620 genera and 12 subfamilies...

 act by chemical means. The sap
Sap
Sap may refer to:* Plant sap, the fluid transported in xylem cells or phloem sieve tube elements of a plant* Sap , a village in the Dunajská Streda District of Slovakia...

 of these plants contains a number of alkaloid
Alkaloid
Alkaloids are a group of naturally occurring chemical compounds that contain mostly basic nitrogen atoms. This group also includes some related compounds with neutral and even weakly acidic properties. Also some synthetic compounds of similar structure are attributed to alkaloids...

s, glycoside
Glycoside
In chemistry, a glycoside is a molecule in which a sugar is bound to a non-carbohydrate moiety, usually a small organic molecule. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. These can be activated by enzyme...

s, saponin
Saponin
Saponins are a class of chemical compounds, one of many secondary metabolites found in natural sources, with saponins found in particular abundance in various plant species...

s, anthraquinone
Anthraquinone
Anthraquinone, also called anthracenedione or dioxoanthracene is an aromatic organic compound with formula . Several isomers are possible, each of which can be viewed as a quinone derivative...

s, and (in the case of plant bulb
Bulb
A bulb is a short stem with fleshy leaves or leaf bases. The leaves often function as food storage organs during dormancy.A bulb's leaf bases, known as scales, generally do not support leaves, but contain food reserves to enable the plant to survive adverse conditions. At the center of the bulb is...

s) irritant calcium oxalate
Oxalate
Oxalate , is the dianion with formula C2O42− also written 22−. Either name is often used for derivatives, such as disodium oxalate, 2C2O42−, or an ester of oxalic acid Oxalate (IUPAC: ethanedioate), is the dianion with formula C2O42− also written (COO)22−. Either...

 crystals - all of which can cause CICD (Mantle and Lennard, 2001).

Butternut squash
Butternut squash
Butternut squash , also known in Australia and New Zealand as butternut pumpkin, is a type of winter squash. It has a sweet, nutty taste similar to that of a pumpkin. It has yellow skin and orange fleshy pulp. When ripe, it turns increasingly deep orange, and becomes sweeter and richer. It grows on...

 and Acorn squash
Acorn squash
Acorn squash , also called pepper squash or Des Moines squash, is a winter squash with distinctive longitudinal ridges and sweet, yellow-orange flesh...

have been known to cause an allergic reaction in many individuals, especially in food preparation where the squash skin is cut and exposed to the epidermis. Food handlers and kitchen workers should take precautions to wear rubber or latex gloves when peeling butternut and acorn squash to avoid temporary Butternut squash (Cucurbita moschata) dermatitis
A contact dermatitis reaction to butternut or acorn squash may result in orange and cracked skin, a sensation of "tightness", "roughness" or "rawness". Applying Cortisone cream to the affected area should stop the reaction within 24 hours.
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