Cutting Fluid Dermatitis

Cutting fluid dermatitis is irritant or allergic contact dermatitis of the hands and forearms from metalworking fluids used for cooling and lubrication in machining. Irritant disease is more frequent than allergic disease.

Fluid types. Straight (neat) oils, soluble oil emulsions, semi-synthetic and fully synthetic water mixed fluids.

Exposure. Machinists, tool setters, grinders, lathe and milling operators, and maintenance workers in engineering and motor manufacturing.

Epidemiology. One of the commonest occupational skin diseases in metalworkers. Risk rises with fluid contamination, high alkalinity, splashing and soaking.

Allergens. Biocides (isothiazolinones, formaldehyde releasers), monoethanolamine, diethanolamine and triethanolamine, colophony, fragrances, anticorrosion additives and sodium omadine.

Related conditions. Oil folliculitis, oil acne, occupational asthma and hypersensitivity pneumonitis from mist and contaminated fluid.

Pathophysiology.

Alkaline pH, emulsifiers and solvents remove skin lipids, and abrasive swarf causes microtrauma. Repeated immersion and glove occlusion further impair the barrier.

Haptens penetrate damaged skin and cause type IV hypersensitivity. Bacterial growth in fluids adds irritants and sensitisers.

• Dry, fissured, erythematous hands, finger webs and forearms; vesicles and lichenification in chronic disease.
• Follicular papules and pustules on forearms and thighs from oil contact.
• Itching and burning after exposure, improved on days off.
• Mist related cough, wheeze or breathlessness in some workers.

Red flags.

• Pustules, crusting or fever (secondary bacterial infection).
• Cough, wheeze or progressive dyspnoea with fever (respiratory involvement).

• Detailed work history: fluid types, concentrations, cleaning of fluids, splash points, gloves and skin care.
• Patch testing with a metalworking fluid series and the patient's own fluids tested at in use concentration, with specialist direction to avoid irritant reactions.
• Review of safety data sheets for allergens.
• Swabs for infection; fluid sampling for bacterial and fungal growth and for pH.
• Spirometry and chest imaging when respiratory symptoms occur.

Differential diagnosis. Irritant dermatitis from solvents and cleaners, allergic dermatitis to rubber, nickel or chromate, atopic eczema, psoriasis, tinea, folliculitis from other causes.

• Control exposure: enclose machines, splash guards, mist extraction, reduce skin contact, automate fluid handling, maintain fluid pH and biocide levels, and replace contaminated fluid.
• Substitute allergenic fluids where patch testing identifies the culprit.
• Nitrile gloves with long cuffs, changed when damp; avoid leather and cotton gloves that absorb fluid; wash hands with mild cleanser and apply a barrier cream before work as an adjunct.
• 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.
• Chronic severe disease: specialist options include alitretinoin and phototherapy.

Monitoring. Review at 4 to 6 weeks, then every 3 months; fluid monitoring at the workplace.

Referral and escalation. Dermatology for patch testing; occupational physician for workplace assessment; respiratory physician for respiratory symptoms; notification and compensation where required.

Special groups. Pregnancy: avoid systemic retinoids; use low potency steroids.