Table 4 Products

It has been well documented that in the investigation of patients suspected to suffer from contact dermatitis, the testing of their own (contact) products is necessary and highly valuable. Unfortunately, knowledge in this field is often minimal and profound mistakes are made. For example, concentrated biocides or plastic monomers are applied under occlusion in undiluted form causing bullous and ulcerative lesions and possibly active sensitization (‘patch test sensitization’). On the other hand, products may be diluted too much or in an inappropriate vehicle resulting in false-negative reactions (8).

Tables 4.1 – 4.7 provide alphabetical listings of certain categories of products for which test recommendations have been recorded. As irritant reactions occur frequently, it is often advisable to test with several dilutions. When positive reactions are obtained, control tests should be performed, preferably on 20 controls or more. False-negative reactions also occur frequently, especially when a product has to be diluted for testing in order to avoid irritant reactions (e.g. soap, shampoo). Table 4.8 lists a number of products which should not be patch tested because of the (possible) risks involved, such as damage to the skin, systemic toxicity or patch test sensitization (8).

In the recommendations, it is often advised to test materials with the ‘semi-open test’ first. In this test, minute amounts of liquid products or products diluted with liquids are applied with a cotton swab on an area (1cm2) of the skin, allowed to dry completely and then covered with acrylate tape. The tape is removed after 2 days and read as ordinary patch tests (8,15). For more information on testing patients’ own products the reader is advised to read the relevant chapters in refs 8 and 15. Much of the information in this chapter has been derived from these sources.

The abbreviations used for the vehicles are as follows:

  • acet = acetone
  • alc = alcohol 70%
  • MEK = methyl ethyl ketone
  • oo = olive oil
  • pet = petrolatum

TABLE 4.1 SOLID MATERIALS

Solid materials, general (8,15)

Solid materials can be tested 'as is', placing scrapings or cut pieces in the test chamber, or they can be applied on acrylic tape, thus avoiding pressure effects (possibly leading to false-positive reactions). The use of ultrasonic bath extracts is an alternative to testing solid materials. Small pieces of the material are placed in water or organic solvent (alcohol, acetone, ether, or water), and extracted in an ultrasonic cleaner device, and finally filtered. Patch testing with thin-layer chromatograms can be valuable for products such as textiles, plastics, food, plants, perfumes, drugs, and grease (964). Suitable extraction vehicles for certain solid materials are as follows:

paper alcohol
plants and wood dusts alcohol, ether, acetone, aqua
plastic materials acetone
rubber materials acetone or aqua
textiles alcohol

Solid materials, specific

Carbon paper as is (6), wetted with acetone (1,2)
Car steering wheel scrapings, as is (1)
Film, (un)developed as is (10)
Latex as is (6), after evaporation of irritant solvent (1)
Leather pieces from the inside and outside , dry and moistened with saline or water (15); test with extracts (1,2); ultrasonic bath extract (15)
Match as is (6)
Match box striking surface, as is (6)
Metal do not test (rough particles) (2)
Photographic paper as is (1,2)
Rubber objects as is and extracts (1,6)
Spectacles scrapings (6); solution of scrapings in acetone (1)
Vinyl films as is (6)

 

TABLE 4.2 COSMETICS AND TOILETRIES

The European Society of Contact Dermatitis advises to test rinse-off cosmetics 1-10% aqua , 'depending on the formulation' (964, no further explanation provided).  

Antiperspirant as is
Bath products, foaming 1% aqua (7); 0.1% aqua (8)
Bleaching creams as is (8)
Depilatories as is, open test (6); as is, semi-open test first (8); thioglycolate 1% pet (7)
Eye cream as is
Eyeliner as is (8)
Eye shadow as is (8)
Face cream as is
Face powder as is (8)
Foundation as is (8)
Fragranced products: allow to dry
      - After-shave lotion as is
      - Deodorants as is; often false-negative, perform ROAT
      - Eau de cologne as is
      - Feminine hygiene spray as is
- Perfume as is (1,8), open and closed (6); as is and 10% alc (2); photopatch test if clinical findings suggest actinic dermatitis
- Toilet water as is

Hair bleach

the ingredients separately (7) and ammonium persulfate (7)
Hair cream as is
Hair dye preparation always perform a semi-open test first: 5 drops dye and 5 drops oxidizing agent; if negative after 48 hours, closed patch test with 2% (8); 10% pet (2); 10% aqua (5); 2% aqua (7)
Hair gel as is, semi-open test first (8)
Hair lacquer as is, dried, open test (6)
Hair lotion as is and 50% oo (1); as is and 50% alc (1,2); as is (5); as is, open test (6)
Hair spray as is, dried, open test (6,8)