Occupational Contact Dermatitis

Occupational contact dermatitis is inflammation of the skin caused by agents handled at work, and is the commonest occupational skin disease. About 80% of cases are irritant and 20% allergic. Hand involvement is present in over 90%. Incidence is 5 to 10 cases per 10,000 full-time workers a year, and it is highest in hairdressers, healthcare workers, cleaners, food handlers, metal workers, mechanics, construction workers and florists.

Irritant dermatitis follows damage to the skin barrier from wet work (exposure to water or gloves for over 2 hours a day, or hand washing more than 20 times a day), detergents, solvents, cutting fluids, acids, alkalis and friction.

Allergic dermatitis is a delayed type IV hypersensitivity to a specific allergen:

• nickel
• chromate in cement
• rubber chemicals (thiurams, carbamates)
• epoxy resin
• acrylates
• formaldehyde releasers
• hair dye (paraphenylenediamine)
• preservatives

Atopic dermatitis, a history of childhood eczema, and filaggrin mutations increase the risk.

The prognosis is poor without early action: about half of workers still have symptoms after 5 years, and many change occupation. Complications: chronic hand eczema, fissures, secondary bacterial infection, secondary sensitization, loss of employment and psychological distress.

• Dry, red, fissured, scaly skin of the dorsal hands, finger webs and wrists, with burning and itching
• Allergic form: vesicles, weeping and edema, with spread beyond contact sites
• Chronic form: lichenification, hyperkeratosis and painful cracks
• Improvement on holidays and days off, and relapse on return to work
• Red flags: a painful weeping eruption with crusts (infection), facial or generalized spread, and diagnostic uncertainty with persistence over 8 weeks

1. Occupational and exposure history: tasks, products, gloves, hand-washing frequency, hobbies and relationship of the dermatitis to work.
2. Patch testing with a baseline series and an occupational series (for example hairdressing, cement, epoxy or metalworking series), read at 48 hours and again at 96 hours. Relevance is judged by exposure.
3. Use tests (repeated open application test) with the workplace product.
4. Exclusion of other causes: skin scrapings with potassium hydroxide for fungus, skin swab for bacteria, and prick tests or specific IgE for latex.
5. Workplace safety data sheets to identify ingredients.

Differentials: atopic hand eczema, endogenous dyshidrotic eczema, psoriasis, tinea manuum, scabies and hyperkeratotic eczema.

1. Prevention and exposure control: avoid identified allergens, substitute products, use gloves matched to the chemical (nitrile or other non-latex gloves, with cotton liners for wet work) for the shortest time needed, and apply barrier and moisturizing creams after work.
2. Emollients: applied at least 3 to 4 times a day, and after every wash.
3. Topical corticosteroid:
   • Mometasone furoate 0.1% ointment once daily for 2 to 4 weeks.
   • Clobetasol propionate 0.05% ointment twice daily for up to 2 weeks for severe palmar disease, then tapering.
4. Steroid-sparing topical agents: tacrolimus 0.1% ointment twice daily for chronic disease.
5. Secondary infection: flucloxacillin 500 mg orally every 6 hours for 7 days (children 12.5 mg/kg every 6 hours).
6. Phototherapy: narrowband ultraviolet B or psoralen with ultraviolet A, 2 to 3 sessions weekly for 6 to 12 weeks.
7. Severe chronic hand eczema:
   • Alitretinoin 30 mg orally once daily for 12 to 24 weeks. It is teratogenic, so women need a negative pregnancy test and effective contraception from 1 month before until 1 month after treatment. Check lipids and liver tests.
   • Ciclosporin 3 to 5 mg/kg a day in two divided doses for up to 12 months, monitoring blood pressure and creatinine.
   • Methotrexate 15 mg orally once weekly with folic acid 5 mg once weekly on a different day, monitoring blood count and liver tests.
   • Prednisolone 0.5 mg/kg orally daily for 5 to 7 days only for severe acute flares.
8. Work modification: redeployment or retraining when control fails, with early notification and compensation processes.

Follow-up every 4 to 6 weeks until clear, then yearly. Counsel on skin protection, which must continue even after healing, since the skin remains vulnerable for months.