Chromium (Potassium Dichromate)
The leather-and-cement metal allergen — and the reason a stubborn foot or hand rash can trace back to your shoes
INCIPotassium Dichromate
- Category
- Metal
- Risk level
- high
- Hexavalent is the problem
- Chromium VI (e.g. potassium dichromate) is a strong sensitiser; EU rules cap it in leather at 3 mg/kg to reduce shoe/glove dermatitis
- A leading occupational allergen
- Cement workers have high chromium-allergy rates from hexavalent chromium in wet cement; it's often persistent, even after exposure stops
- Travels with other metals
- Frequently co-occurs with nickel and cobalt allergy in metal-sensitive people
- Patch test
- Potassium dichromate 0.5% sits in the baseline patch-test series
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Commonly found in
Possible reactions
- Persistent, itchy hand or foot dermatitis
- Foot dermatitis from leather shoes (a common, overlooked cause)
- Chronic hand eczema in cement/construction workers
- Skin ulcers ("chrome holes") from heavy occupational exposure
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What is chromium (and potassium dichromate)?
Chromium comes in different forms that behave very differently. Trivalent chromium (Cr III) is an essential trace nutrient. Hexavalent chromium (Cr VI) — including potassium dichromate — is a strong sensitiser and irritant, and it's the form that matters for allergy. Potassium dichromate is the standard patch-test reference for chromium allergy.
Where do people actually meet it? Two big sources and one cosmetic one:
- Chrome-tanned leather — the great majority of leather (shoes, belts, watch straps, gloves) is tanned with chromium salts.
- Wet cement — a major occupational source.
- Cosmetics — chromium green pigments (Chromium Oxide Greens, CI 77288; chromium hydroxide green) in some eyeshadows and liners; and some green/yellow tattoo inks.
Why chromium causes reactions
Hexavalent chromium penetrates skin readily and binds proteins to trigger a robust Type IV delayed hypersensitivity. Two features make it clinically important:
- It's persistent. Once sensitised, people react to very low levels, and the dermatitis tends to be chronic — sometimes continuing even after the exposure ends.
- It spreads. Reactions aren't always confined to the contact site. In leather, sweat and friction increase chromium leaching, which is why shoe and watch-strap dermatitis is common.
Cosmetic chromium (the green pigments) is generally a smaller risk than leather or cement, but sensitised people can still react to green makeup.
Chromium is my go-to example of "the allergen isn't always in the bathroom cabinet." People scrutinise their skincare while standing in chrome-tanned shoes that are the actual cause of a months-long foot rash. If a foot rash won't quit and antifungals do nothing, look down at what you're wearing before you blame your moisturiser. — Snehal
Where it's found
- Chrome-tanned leather — shoes, belts, straps, gloves, bag handles.
- Wet cement — construction, masonry, tiling.
- Green cosmetic pigments — some eyeshadows/liners (CI 77288).
- Some tattoo inks — green and yellow shades.
How to avoid it
- Read cosmetic labels for Chromium Oxide Greens (CI 77288) and Chromium Hydroxide Green — mainly an issue for green eye makeup.
- Choose chrome-free leather — vegetable-tanned or certified "chrome-free"/"metal-free", or non-leather (canvas, fabric, synthetic).
- Protect against cement — barrier creams, proper gloves, and lower-chromium (reduced) cement where available.
- Ask about ink — chromium-free options for green/yellow tattoos.
- Patch test for unexplained chronic hand/foot dermatitis.
Safer alternatives
- Cosmetics: iron-oxide greens, ultramarine greens, or neutral/brown palettes.
- Leather goods: vegetable-tanned leather, cork, recycled materials, quality synthetics.
- Occupational: PPE, low-chromium cement, workplace chromium-safety practice.
The bottom line
Chromium — specifically hexavalent chromium in chrome-tanned leather and wet cement — is a potent, persistent contact allergen, and a classic overlooked cause of chronic foot and hand dermatitis. In cosmetics it's mainly the green pigments. Switch to chrome-free leather and non-chromium green makeup, protect against cement, and patch test to confirm — and remember the culprit might be on your feet, not in your routine.
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