Covered patch test

A small area of the outer surface of the upper arm is exposed to test and control materials under occlusive cover. The test and control materials are applied to round chambers and taped to the arm with surgical tape. A standard irritant (20% sodium dodecyl sulphate [SDS]) is used as the positive control. Each panellist has up to four patches applied, each patch being applied for an increased duration. Due to the potential irritancy of the test materials a cautious approach is used. The first patch is applied for one hour, the second, third, and fourth patches for two, three, and four hours, respectively. Each patch is applied to a different site on consecutive weeks. This approach allows any unexpected or unacceptable reactions to be limited to a minimum. 

A 36-year-old dermatologist with a history of jewellery intolerance developed dermatitis on the right side of the chin, with red pruritic papules. The dermatitis had worsened after prolonged use of her mobile phone. Patch tests were positive to nickel sulfate. She solved the problem by covering the phone with a plastic case. 

A 32-year-old woman developed dermatitis on her left cheek and suggested that it might have been caused or worsened by her mobile phone. Patch tests showed only positive reaction to nickel sulfate. The dimethylglyox-ime test for nickel on the side of her phone was positive. The skin lesion resolved rapidly after she covered the phone with a plastic case. 

CMA. 1992. Repeated insult patch test to evaluate sensitization potential of ethylene glycol monobutyl ether with cover letter dated 05/26/93. EPA/OTS Doc 86-930000207. 

Fig. 6 Pustular drug eruption (AGEP) disseminated pustules cover the skin. Histologically, the pustules are intraepidermal and nonfollicular. A patch test reaction to the eliciting drags can lead to a pustular reaction as well for details see text...

Another possible explanation of the observed reactions are the additives in pharmaceutical preparations. Thus Lagerholm et al. (1958) reported a case of hypersensitivity to benzyl alcohol added as a preservative to vitamin B 2 preparations, resulting in urticaria after injection, Hovding (1968), however, was not able to demonstrate a positive skin reaction either with benzyl alcohol or with cobalt chloride. However, skin tests with commercial brands of cyanocobalamin and hydroxocobalamin as well as with purified cyanocabalamin and hydroxocobalamin were positive. Malten (1975) reports a flare reaction in a woman due to the third injection of 250 pg vitamin B12. Prick and patch tests, however, remained negative. A recent short review of reactions after administration of vitamin Bj2 preparations was published by Meuwissen (1978). An extensive review covering the literature up to 1975 was presented by Faivre et al. (1975). The authors conclude that, despite the widespread use of vitamin B12 preparations, cases of accidents after vitamin Bi2 administration are very rare, but nevertheless are a potential risk. Therefore, skin and immunologic tests should be made prior to administration and especially parenteral application of the vitamin. The authors do not make an explicit statement as to a definite allergic mechanism of the observed phenomena. 

Nickel was named Contact Allergen of the Year in 2008 by the American Contact Dermatitis Society, and the rates of positive patch tests have been increasing year by year [83 ]. The European Union (EU) adopted the EU Nickel Directive in 1994 it limits nickel release from body piercing equipment to <0.2 micrograms/cm /week [84 ]. Despite this, of 95 nickel-allergic patients with dermatitis in Denmark, 70 had 151 metallic items, 66 of which contained nickel, detected using the dimethyl-glyoxime test, and nearly all had been purchased or acquired after the introduction of the EU Nickel Directive [85 ] however, few were items covered by the Directive and the rates of release were not studied (Table 2). 

A 37-year-old Japanese man developed multiple pruritic emptions covering his entire body 3 months after multiple dental fillings. A lymphocyte stimulation test was positive to zinc chloride. A skin patch test with zinc chloride caused a severe widespread flare-up, as did removal of each of the zinc dental fillings one by one. 

Repeat application patch tests in which diluted materials are applied to the same site each day for 15-21 days have been reported using several species (the guinea pig or rabbit being most commonly used) (Phillips et al. 1972). Because the degree of occlusion is an important determinant of percutaneous penetration, the choice of covering materials may determine the sensitivity of a given test (Mag-nusson and Hersle 1965). A reference material of... 

Dooms-Goossens (1995) has suggested the use of a semi-open test for testing patient-supplied products. Minute amounts (about 1-2 jiL) of the liquid product are applied with a cotton swab on an area (1 cm ) of the skin, allowed to dry completely, then covered with acrylate tape. The tape is removed after 2 days and read as ordinary patch tests. Dooms-Goossens has rarely seen very strong reactions using this technique. 

As a constituent of the oils of some flowers, spices and cranberries, benzoic acid also occurs naturally. It has some antimycotic (6% in Whitfeld ointment) and antibiotic properties and is capable of producing immediate contact reactions (immunological and non-immunological) in the same concentrations (Bas-ketter and Wilhelm 1996 Coverly et al. 1998). The patch-test concentration is 5% pet. Allergic reactions are considered uncommon. 

Repellents on Cloth. Each candidate repellent is appHed to a knit cotton stocking or cloth patch at 3.3 g/m cloth, usually as a 1% solution of active ingredient (AI) ia acetone. Two hours later, the stock or cloth patch is placed over an untreated nylon stocking on the arm of a subject, the hand covered, and the arm exposed to 1500 female mosquitoes for one minute. If fewer than five bites are counted, the test is repeated at 24 h, then weekly until failure, which is, by definition, five bites per minute. The standard mosquitoes used are Piedes aegppti Anopheles quadrimaculatus or M. albimanus. Candidate repellents ia cloth tests are ia one of the foUowiag classes class 1, effective 0 d class 2, 1—5 d class 3, 6—10 d class 4, 11—21 d and class 5, >21 d. 

The entire trunk of the animal is covered with an impervious material (such as Saran Wrap) for a 24-h period of exposure. The Saran Wrap is secured by wrapping several long strips of athletic adhesive tape around the trunk of the animal. The impervious material aids in maintaining the position of the patches and retards evaporation of volatile test substances. 

The extent of the skin irritation caused the sample was evaluated using the Draize method [7] on the skin of rabbits. Each animal was tested on a patch of unbroken skin. Each test area was treated with 0.5 g of the test substance. The test areas were covered for four hours. Inspections of the test areas for signs of erythema... 

A dose of 0.5 mL of liquid or 0.5 g of solid or semisolid test chemical is applied to the site. Separate animals are not required for an untreated control group, since adjacent areas of untreated skin serve as controls for the test. The test chemical should be applied to a small area (approximately 6 cm2) of skin and covered with a gauze patch, held in place with nonirritating tape. In the case of liquids or some pastes, it may be necessary to apply the test chemical to the guaze patch and apply that to the skin. The patch should be loosely held in contact with the skin by means of a suitable occlusive dressing for the duration of the exposure period. The animals access to the patch and resultant ingestion of the test chemical by licking or by inhalation should be prevented. 

Berkeley Scarifier as described by Haley et al. (1974). Materials are tested undiluted, and 0.5 ml liquid, or 0.5 g solid or semisolid material is applied. Each test site is covered with two layers of 1-in square surgical gauze secured in place with tape. The entire trunk of the animal is then wrapped with rubberized cloth or other occlusive impervious material to retard evaporation of the substances and hold the patches in one position. The wrappings are removed 24 h after application and the test sites are evaluated for erythema and edema using a prescribed scale. Evaluations of abraded and intact sites are recorded separately. Test sites are evaluated again 48 h later (72 h after application) using the same scale. 

Repeat Animal Patch (RAP) test - compares irritation potential of surfactants. Solutions were applied to the clipped back of immobilized albino mice with a saturated cotton-tipped applicator. The test site was covered with a rubber dam to prevent evaporation. This process was repeated seven times at intervals of 10 min. The skins were evaluated microscopically for epidermal erosion. 

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