What are the types of allergens in the True Test (patch test) and common related materials?

From the Guidelines

The TRUE Test (patch test) is a standardized method to identify contact allergens causing allergic dermatitis, and it includes metals, rubber compounds, preservatives, fragrances, topical medications, and resins as the main types of allergens. The main types of allergens in the TRUE Test include metals (nickel sulfate, potassium dichromate, cobalt chloride), rubber compounds (thiuram mix, mercapto mix), preservatives (formaldehyde, quaternium-15, methylisothiazolinone), fragrances (fragrance mix, Balsam of Peru), topical medications (neomycin, benzocaine), and resins (epoxy resin, p-phenylenediamine) 1. These allergens are commonly found in everyday items, such as:

• Nickel in jewelry and metal buttons
• Chromium in leather products and cement
• Rubber compounds in gloves and elastic materials
• Preservatives in cosmetics, lotions, and cleaning products
• Fragrances in perfumes and scented products
• Topical medications in over-the-counter creams
• Resins in hair dyes, adhesives, and plastics. The patch test works by applying small amounts of these potential allergens to the skin (usually the back) under occlusive patches for 48 hours, then reading the skin's reaction after removal and again 2-4 days later 1. Positive reactions appear as redness, swelling, or blistering at the test site, indicating sensitivity to that specific allergen. Identifying these allergens allows patients to avoid specific substances causing their skin reactions, which is crucial for reducing morbidity, mortality, and improving quality of life. Preprepared tests, like the TRUE Test, are significantly more reliable than operator-prepared tests, and larger chambers may give more reproducible tests 1.

From the Research

Types of Allergens in True Test (Patch Test)

• The TRUE Test panels contain 42 unique allergens and four complex mixtures, including nickel, cobalt, and chromium 2.
• The test has been clinically standardized with serial dilution tests on sensitized patients and validated in comparative multicenter tests 3.
• The TRUE Test patch test system has been compared to the chamber system recommended by the North American Contact Dermatitis Group, showing concordance of results in 98% of tests with nickel, epoxy resin, and ethylenediamine dihydrochloride 4.

Common Known Materials Related to Allergens

• Jewelry is the most commonly identified source of nickel and cobalt for both solitary and concurrent metal allergy 5.
• Other sources of exposure to allergens on the TRUE Test panels include:
  • Metals (e.g. nickel, cobalt, chromium) in everyday objects such as coins, buckles, and leather 5, 6.
  • Epoxy resin in adhesives, coatings, and plastics 4.
  • Ethylenediamine dihydrochloride in rubber and other materials 4.
• The prevalence of sensitization to nickel, cobalt, and chromium can vary by geographical and socio-cultural factors, as well as by age and sex 6.