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Contact Dermatitis. 2004 Aug;51(2):73-8.

Poor correlation between stated and found concentrations of diphenylmethane-4,4'-diisocyanate (4,4'-MDI) in petrolatum patch-test preparations.

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Department of Occupational and Environmental Dermatology, Malmö University Hospital, Malmö, Sweden.


Diphenylmethane diisocyanate (MDI) is widely used in its polymeric form in the manufacturing of polyurethane products. Previous reports on MDI-related contact allergy have shown a pattern, where patients seem to react to their own MDI-based work material but not to commercial patch-test preparations, which contain 4,4'-MDI. Therefore, we performed chemical analyses of 14 commercial test preparations of 4,4'-MDI obtained from 8 European and 4 American dermatology departments as well as 2 preparations from 2 major European suppliers of patch-test allergens. A new method for monitoring 4,4'-MDI in petrolatum preparations was developed and the determination of 4,4'-MDI as the MDI-dibutylamine derivative using liquid chromatography-mass spectrometry was performed. None of the preparations obtained from the dermatology departments contained more than 12% of the concentration stated on the label. In most cases, 4,4'-MDI content was only a few percentages or less of the concentration stated. 7 of the 14 preparations were analysed before the expiry date. Yet, only 1 of them, a preparation directly obtained from the supplier, came close to the concentration stated on the label. Thus, using these preparations, patients will be tested with a lower concentration than intended, leading to possible false-negative reactions.

[Indexed for MEDLINE]

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