S. Fregert

Contact allergy to the preservative Kathon® CG

Of 976 patients routinely patch tested with Kathon® CG (Rohm & Haas), 300 ppm. 43 (4.4%) gave a positive reaction. Of 170 patients routinely tested with Kathon® CG 250 ppm, 10 (5.9%) gave a positive reaction. Out of 34 patients tested with serial dilution of Kathon® CG, 17 (50%) reacted to to 100 ppm, 8 to 30 ppm and 2 to 10 ppm. The concentration of 1000 ppm of Rathon® CG was irritant in some cases, but 300 ppm was not irritant.

A study on expert reading of patch test reactions: inter-individual accordance

To diagnose allergic or irritant contact dermatitis, a clinically relevant contact allergy has to be demonstrated or ruled out, respectively. Although patch testing has been used for 100 years, it remains the method of choice for diagnosing contact allergy. A disadvantage of patch testing is that reading is subjective, based on inspection and palpation of the test area, implying that the assessment is subject to the readers knowledge and experience. This study was carried out to investigate the accordance in reading patch test reactions between 5 dermatologists. 4 groups, each with 10 patients, participated. Within each group, all 10 were allergic to one and the same sensitizer; nickel, epoxy resin, ethylenediamine, or Kathon CG. The sensitizers were tested in serial dilutions and applied randomly to the back. The tests were read independently by the dermatologists in a blinded fashion. A protocol was used where the dermatologists had to note the presence of the morphological features erythema, infiltration, papules, vesicles, and bullae. In this way, it was possible to allocate the various readings into 4 classification systems, 3 European and one American, although the definition of the various classifications might differ slightly. Based on the readings and classifications, it was possible to calculate the degree of accordance within the 4 systems used. It was also possible to analyze the degree of accordance for the various morphological features. Total accordance for the 5 reading dermatologists for positive and negative test reactions was noted in 36% and 46%, respectively. The 3 European systems require homogenous erythema and infiltration for a reaction to be classified as allergic, while the American system also requires the presence of papules. Therefore, a higher number of allergic reactions (9%) was obtained with the European systems. Between the 4 classification systems, there were statistically significant differences, with the highest number of deviations for the system in which papules had discriminatory significance. When looking at the various morphological features, papules were most difficult to assess, followed by vesicles. Preferably, a classification system should not depend on papules. In conclusion, there was good accordance among the dermatologists in reading patch test reactions, since the 5 dermatologists read 82% of all tests similarly.

A simple method for the detection of formaldehyde.

The commonly used chromotropic acid method for the determination of formaldehyde sometimes produces a masking discolouration. We have therefore evaluated a complementary method in which acetylacetone is used as the reagent. By a combination of the 2 methods, formaldehyde can be traced in most products.

Reliability of the chromotropic acid method for qualitative formaldehyde determination

Some questions. Probably there is contact sensitivity but is the dermatitis allergic eczematous; it looks more irritant, remains localized and does not vesiculate, thus lacking two of the cardinal signs of AECD. What is a correct patch test concentration? I find that more than 10 % is often irritant. What is the sensitizer? It seems to be water and ethanol soluble. Is it allyldisulphide which produces positive patch test reactions in some patients at 5 % pet.? Is it alliin or allicin or a breakdown product difficult to isolate? A major problem is patch testing in a suitable concentration with substances which are highly irritant and also labile. For practical management of such patients I do not patch test with garlic. A voidance of garlic is recommended but often does not seem to help this particular type of desiccated dermatitis. Nearly all of the culinary vegetables used by the homemaker have been reported to cause contact dermatitis in an industrial setting of large exposure (Mitchell & Rook 1978). Yet we rarely patch test for vegetable dermatitis in housewifes eczema. Significant screening and aimed test sets, appropriately standardized in nonirritant concentration and suitably preserved, are needed for vegetable AECD together with scratch/prick test sets for vegetable contact urticaria. The last has also been reported for Allium and is suspect in some of our cases.

Detection of formaldehyde in corticoid creams

In a previous report it was shown that the chromotropic acid method for determination of formaldehyde could give false negative results by discoloration (Dahlquist et a!. 1980). Therefore a fluorimetric method was used (Wilson 1974). This method had to be modified as we analyzed creams and not solutions. Formaldehyde was extracted from the specimens with 10 % methanol in water under magnetic stirring for 1 h. The extract was incubated with the reagent at 60° C for 1 h. The sample was filtered through a Millipor® teflon filter (0.22 f!m). (Some Millipor cellulose filters contained formaldehyde.) After measurement of the emission, the samples were examined by scanning from 400 to 700 nm to check that the maximum emission was at 510 nm. The detection limit was 5 f!g formaldehyde/g. Cosmetics, topical medicaments, dish washing liquids and shampoos giving discoloration with the chromotropic acid method were analyzed with the fluorimetric method. About half of the samples giving discoloration contained formaldehyde, confirming that the chromotropic acid method can give false negative results. Out of 20 corticoid creams, 16 gave positive reactions with the chromotropic acid method, but none gave discoloration. Analyzed with the fluorimetric method, these creams were found to contain up to 51 f!g formaldehyde/g. In seven corticoid ointments no formaldehyde amount above the detection limit was found. When the constituents of the creams were analyzed, formaldehyde was found in polyethylene glycols (carbowaxes, macrogol) and in derivatives of these. It is known that autoxidation of polyethylene glycols and derivatives gives formaldehyde among other compounds, and that heat increases the degradation (Rieger 1975, Hamburger et a!. 1975). Sterilization of corticoid creams and ointments is prescribed by Swedish law. The preparations are commonly heated at 140° C for 3 h. To investigate the formation of formaldehyde, polyethylene glycols and some derivatives were heated at 140° C for 3 h. Formaldehyde was determined by the qualitative chromotropic acid method. Several polyethylene glycols that had been stored in the laboratory contained formaldehyde. Only those free from formaldehyde were heated. Carbowax 400, 1500, 3000 and 4000 contained formaldehyde after heating. The derivatives Tween 60® (polyoxyethylene sorbitan monostearate) and Cetomacrogol (Texofor AlP, polyethylene glycol monocetylether) also formed formaldehyde during the heating procedure. When emulsions are made they are often heated at about 70° C. The Carbowax 3000 was heated at 70° C for 30 min and then contained formaldehyde. The amounts of formaldehyde found are probably not high enough to induce sensitization, but may maintain dermatitis in previously formaldehyde-sensitized subjects. The formaldehyde in the samples analyzed is, however, a contaminant, so the amount may vary between batches.

Allergic contact dermatitis from cardamom.

A case is presented of a confectioner with a chronic hand dermatitis and positive patch test reactions to cardamom and certain terpenoid compounds present in the dried ripe seeds of cardamom. Cardamom is a popular traditional flavouring agent for baked goods and confectionery. Dermatitis from skin exposure to cardamom has to the best of our knowledge not been reported. We report one case of allergic contact dermatitis to cardamom elicited by terpenes present in the seeds.

The primula allergen primin

Contact dermatitis to sunscreen agents of the P ABA, salicylate, and cinnamate types is well documented (Fisher 1973). A patient with contact dermatitis to dioxybenzone in a sunscreen preparation has recently been observed. The patient was a 46-year-old sheet metal worker who has admitted to the dermatology service of the Miami Veterans Administration Hospital for a scaling, hyperpigmented, impetiginized dermatitis of the face, neck and upper chest and back. Skin biopsy showed findings consistent with chronic contact dermatitis. He had been using several topical preparations, including Solbar®, which is composed of oxybenzone 3 % and dioxybenzone 3 % in a vehicle containing methyl cellulose, isopropyl myristate, methylphenylpolysiloxane, methyl paraben and propyl paraben. The patient was treated with compresses and oral cloxacillin, and his eruption promptly cleared. Standard patch tests to the following materials were performed:

Deutung und Bedeutung von Testreaktionen

Vor der Feststellung der Relevanz einer Testreaktion mus bei der Ablesung gepruft werden, ob die Reaktion den Kriterien einer allergischen Reaktion entspricht (S.24) und ob es sich nicht um eine falsch positive Reaktion handelt (S. 33).

Allgemeine Allergen-(Ekzematogen)Kunde

Es gibt Testsubstanzen, welche in keiner Konzentration und unter keiner auserlich modifizierbaren Bedingung die Haut obligat zu reizen vermogen. Solche Substanzen sind beispielsweise das Benzocain, die Lanolinalkohole oder das Neomycin.

Ablesung der Testreaktionen

Ein Erythem ist noch kein sicheres Zeichen einer allergischen Reaktion. Es sollte in der Regel als fraglich (= ? +) bewertet werden. Dennoch rufen solche Produkte, wie Kosmetika, Salbengrundlagen oder Textilien, welche nur geringe Konzentrationen des Allergens enthalten, lediglich Erytheme hervor. Sie konnen also den Wert einer echten positiven Reaktion haben. Ein Erythem darf nicht mit dem rotlichen Schimmer, welchen einige Farbstoffe verursachen, verwechselt werden.