Chromate Dermatitis

Chromate dermatitis is allergic or irritant contact dermatitis caused by hexavalent chromium (chromate), most often in cement workers, leather handlers and metal workers. It tends to be chronic and relapsing.

Sources. Wet cement and mortar, chrome tanned leather (shoes, gloves, watch straps), paints and anticorrosive primers containing zinc chromate, chromium plating, welding of stainless steel, wood preservatives and some matches and bleaches.

Epidemiology. Sensitisation affects about 1 to 2% of patch tested patients. Rates fell after reduction of soluble hexavalent chromium in cement with ferrous sulphate.

Associated harms. Chrome ulcers, nasal septal ulceration and perforation, occupational asthma, and increased lung and sinonasal cancer risk with inhaled hexavalent chromium.

Course. Sensitisation is lifelong, and relapses persist even after exposure falls.

Pathophysiology.

Hexavalent chromium crosses the skin easily and is reduced intracellularly to trivalent chromium, which binds proteins and acts as a hapten. This leads to type IV hypersensitivity.

Chromate is also directly corrosive, causing painless ulcers on injured skin.

• Hand and forearm eczema, often chronic, with fissures and lichenification; foot eczema from leather.
• Chrome ulcers: sharply punched out, painless ulcers on knuckles, fingers or forearms.
• Nasal crusting, bleeding or septal perforation after inhalation.
• Flares after contact with cement, leather or paint.

Red flags.

• Spreading erythema or pus (secondary infection).
• Haemoptysis, persistent cough or new nasal bleeding in long term exposed workers.

• Exposure history including cement, leather and paint contact, and effect of time away from work.
• Patch testing with potassium dichromate 0.5% in petrolatum (lower concentrations are used in some series to limit irritant reactions); read at day 2 and day 4 or later.
• Diphenylcarbazide spot test to detect hexavalent chromium on leather and surfaces.
• Nasal examination for septal change; chest imaging and lung function when inhalation exposure is significant.
• Swabs when infection is suspected.

Differential diagnosis. Irritant contact dermatitis from wet cement, allergic contact dermatitis to cobalt, nickel or rubber, atopic eczema, psoriasis, tinea, nummular eczema.

• Avoid chromate: iron sulphate treated cement, vegetable tanned leather and chromate free products.
• Protective nitrile gloves with long cuffs, changed when damp; protective clothing; thorough washing after work.
• Emollient applied liberally at least twice daily and after each handwash, long term.
• Clobetasol propionate 0.05% ointment topically to affected skin once or twice daily for up to 2 weeks, maximum 50 g weekly. Monitor skin atrophy, striae, telangiectasia and infection. Avoid on the face, flexures and genitals and on infected skin; use the lowest potency that works in pregnancy and avoid in children.
• Severe acute flare: prednisolone 40 mg orally once daily in the morning for 5 days, then 20 mg for 5 days, then 10 mg for 5 days, then stop. Maximum 40 mg daily. Monitor glucose, blood pressure and mood. Caution in diabetes, peptic ulcer and infection; acceptable in pregnancy when needed; no renal adjustment.
• Chrome ulcers: clean, protect and treat infection by swab; heal over 2 to 4 weeks after exposure stops.
• Advise early job change when avoidance is not possible; prognosis is poor with continued exposure.

Monitoring. Review at 4 to 6 weeks, then every 3 months; annual review of nose and chest for exposed workers.

Referral and escalation. Dermatology for patch testing and chronic disease; occupational physician for workplace change; ENT for septal perforation; notification and compensation where required.

Special groups. Pregnancy: avoid potent steroids over large areas. Children: avoid chrome tanned footwear in sensitised patients.