Irritant Contact Dermatitis (ICD) is a skin inflammation that is confined to a specific body location and independent of any immunological disorder. It is one of the two main forms of contact dermatitis, the other being allergic contact dermatitis (ACD), which is associated with an immune reaction.

Irritant contact dermatitis occurs as a direct cytotoxic (killing cells or preventing cell division) reaction of the skin when it is exposed to a chemical or physical substance. Irritant contact dermatitis is an issue of public health concern due to its occupational association. In fact, estimates suggest that irritant contact dermatitis incurs an annual expenditure of up to $1 billion in the USA, which includes medical costs, employee reimbursement, and work time loss.

The first historical report of skin irritation caused by metal contact was in the writings of Celsus around 100 AD, the first proper description of occupational skin problems among miners was furnished by Georg Agricola in 1556. Occupational irritant dermatitis (OID) came under medical analysis during the industrial revolution with advancements in industrial and domestic materials and chemicals.

Prevalence

Irritant contact dermatitis accounts for an estimated 70% to 80% of all occupational skin hazards. The US Bureau of Labor Statistics (BLS) reported that patients with industrial skin hazards constituted a constant 30% to 45% of all occupational ailments through the 1970s to mid 1980s. Right now, skin ailments constitute only 10% to 15% of all industrial illnesses so the situation has probably improved through better work safety procedures. However, the BLS survey has a drawback since it includes only private concerns in the US. The occurrence of occupational skin hazards in other nations is also reported as an annual statistic of 50 to 70 patients per 100,000 employees. Workers who form the high-risk category are:

• Caterers
• Furniture makers
• Hospital staff
• Hairdressers
• Chemical industry staff
• Dry cleaners
• Metal workers
• Florists
• Warehouse workers

Clinical appearance

Clinical presentation is dependent on the following factors:

• Attributes of the irritant agent
• Patient characteristic such as age, race, gender, genetics, habits, medical history of skin disease, the area of exposure and sebaceous condition
• Environmental factors include concentration, mechanical pressure, temperature, humidity, pH, repetitiveness and duration of exposure

The common clinical features are of two categories:

1. Features caused by highly potent strong or pure irritants (acids, alkalis, oxidants) are:

• Redness of the skin (erythema)
• Excess fluid accumulation in tissue cells (Edema)
• Fluid-filled blisters or cysts, which may turn into necrosis (death of tissues) and ulceration (chemical burns) in acute cases

2. Features associated with chronic irritant contact dermatitis from frequent contact with inferior or secondary irritants (soaps, solvents, cleansers) are:

• Erythema
• Lichenification
• Excoriations or skin destruction
• Scaling
• Fissures

Clinical variations of irritant contact dermatitis are:

• Acute Irritant Contact Dermatitis
• Acute Delayed Irritant Contact Dermatitis
• Irritant Reaction Irritant Contact Dermatitis
• Cumulative Irritant Contact Dermatitis
• Asteatotic Dermatitis
• Traumatic Irritant Contact Dermatitis
• Pustular and Acneiform Irritant Contact Dermatitis
• Non-erythematous Irritant Contact Dermatitis
• Subjective or Sensory Irritant Contact Dermatitis
• Airborne Irritant Contact Dermatitis
• Frictional Irritant Contact Dermatitis

The various forms of irritant chemicals are:

• Skin corroding acids; both inorganic and organic
• Alkalis or bases
• Metal salts
• Solvents
• Disinfectants
• Alcohols
• Plastics
• Food
• Fabrics
• Plants

Distinguishing irritant contact dermatitis and allergic contact dermatitis

Despite a different pathogeneses, allergic contact dermatitis and irritant contact dermatitis have identical clinical appearances, histology (microscopic tissue study), and immunohistology, especially in chronic cases. Hence, they must be carefully distinguished.

They have common clinical manifestations like erythema, papules, xerosis, scaling and lichenification. Moreover, both have a localized spread and well-defined outlines that indicate the body locations that have been exposed to the irritant. It is also difficult to identify the causative agents, the concentration and duration of contact separately for irritant contact dermatitis and allergic contact dermatitis.

Hence, the prognosis of irritant contact dermatitis must follow a strategy of exclusion. The best means to go about it is to exclude cases, which cannot be identified by a positive patch test to recognized allergens. This apart, here are a few indications that can help differentiate irritant contact dermatitis and allergic contact dermatitis:

• More regular burning and stinging in irritant contact dermatitis
• Pruritus (itchiness) of inflamed sites in allergic contact dermatitis

Treatment

The first line of management of irritant contact dermatitis is avoiding the contributing irritant agents, which involves preventive measures at home and at the workplace.

The second means is the use of drugs and alternative therapies aimed at restoring normal skin barrier functions. They include use of topical corticosteroids, systemic corticosteroids (acute cases), photochemotherapy (PUVA) and superficial radiation (Grenz ray) and the combined use of systemic retinoids.