A positive potassium dichromate patch test can lead to two very different exposure investigations. Wet cement points toward hands, forearms, knees, boots, tasks, and workplace controls. Chromium-tanned leather points toward shoes, gloves, watch straps, furniture, or another area of sustained material contact. The patch test identifies sensitization to the test substance; the rash location and exposure history help determine whether cement, leather, or something else is currently relevant.
Cement combines irritation, burns, and allergy risks
Wet cement is alkaline and abrasive. It can cause irritant dermatitis and chemical burns without contact allergy. Cement can also contain hexavalent chromium, or chromate, which can cause allergic contact dermatitis after sensitization. These mechanisms can occur together, so itching or cracking during cement work does not identify the mechanism by appearance alone.
The U.K. Health and Safety Executive recommends assessing the actual cement task, reducing contact where possible, and keeping required controls effective. Suitable gloves must be selected for the substance and duration, and cuffs must not trap wet cement against skin. Some cement contains a reducing agent intended to lower hexavalent chromium, but HSE warns that its effect is limited to the product's shelf life. A patch-test result is not a reason to work without PPE or to substitute an unverified glove.
Leather creates a different site-and-material question
Chromium compounds are widely used in leather tanning. In a 2012 footwear study, investigators measured chromium in 60 pairs of leather shoes and assessed release under laboratory conditions. The study supports leather footwear as a plausible source, but a material category does not prove the cause of one person's rash. Dyes, adhesives, rubber chemicals, friction, sweat, and occlusion can also matter. “Vegetable tanned” or another marketing claim is not proof that a finished item is free of chromium or every other contact allergen. The lining and insole may also differ from the upper, so record which surface touches the affected skin.
A study published in 2026 analyzed 4,830 adults who were consecutively patch tested at a Danish clinic from 2016 through 2024. Chromium allergy was associated with hand, leg, and foot dermatitis, and leather shoes were the most frequently identified exposure. These are results from one patch-test clinic, not population prevalence. They show how body site can guide the next question; they do not make every leather shoe relevant to every positive test. Read the study abstract.
Hypothetical worked example
A bricklayer has hand dermatitis and a separate itchy patch on the top of one foot. The work log shows daily wet-mortar contact and occasional cement inside a glove cuff. The footwear log shows the foot patch under the edge of a leather safety shoe. Both routes deserve investigation. The pattern does not prove that chromate caused either rash, and replacing required footwear without a safety review could create a different hazard.
Investigate by body site, task, and material
- Start with the report. Record potassium dichromate's reaction grade, reading days, and the clinic's current-relevance assessment.
- Draw the distribution. Mark hands, finger webs, wrists, forearms, knees, lower legs, feet, and any sharp edge that matches a cuff, shoe panel, strap, or glove.
- Describe cement work. Record mixing, laying, cleanup, splashes, wet clothing, glove and boot use, product age, safety data sheets, and symptom changes away from work.
- Describe leather contact. Photograph the item and lining, note the contact area, sweat and wear time, purchase date, material statement, adhesives, and other nearby components.
- Keep other metals separate. A cobalt or nickel result beside chromate is co-positivity. It does not, by itself, prove cross-reaction or show which exposure caused the current rash.
Ask the patch-test clinician which exposure best fits each body site and whether additional occupational, footwear, rubber, adhesive, or dye testing is warranted. Ask occupational health which task controls can reduce skin contact while preserving respiratory, chemical, and physical protection. Do not start a low-chromium diet, avoid all metal, scrape material onto the skin, or abandon safety equipment based on a patch-test name. For another example of site-based metal investigation, see the cobalt exposure guide.
Sources
- Larsen CK, et al. Trends in Contact Allergy to Chromium Following the 2015 European Union Leather Regulation. Contact Dermatitis. 2026;94(1):67–72. PMID: 41184202. DOI: 10.1111/cod.70045.
- Thyssen JP, et al. Chromium in leather footwear—risk assessment of chromium allergy and dermatitis. Contact Dermatitis. 2012;66(5):279–285. PMID: 22486570.
- U.K. Health and Safety Executive. Construction hazardous substances: Cement. Updated September 4, 2025.
- Uter W, et al. European Society of Contact Dermatitis guideline for diagnostic patch testing, update 2026. Contact Dermatitis. 2026. DOI: 10.1111/cod.70195.