Allergens in solid material, an optimization study of the extraction of rubber gloves at patch testing
O. Bergendorff*, C. Persson, C. Hansson
Department of Dermatology, Lund University, Lund, Sweden
Background
In the production of rubber, hundreds of chemicals are used. Many of these chemicals are allergenic and allergic contact dermatitis is one of the most prevalent occupational diseases. This has since long been a major problem among workers in the rubber production. An increasing number of rubber allergic patients have been registered among persons using rubber products such as protective gloves or working with rubber details in assembling industries. At evaluation of allergy to rubber products the pure chemicals are tested in an appropriate vehicle and often also with the solid material as is and as an extract of it. Positive patch tests to pure rubber chemicals are often found but with irritative or negative tests for the extracts and the solid material. Extraction of allergens from solid materials is done at many test laboratories but no analysis of the techniques used has been described before. This study concerns an evaluation of the technique used at extraction of rubber allergens from solid rubber products.
Methods
A rubber glove containing two dithiocarbamates, zinc pentamethylenedithiocarbamate (ZPD) and zinc dibutyldithiocarbamate (ZDBC), was used as a model for rubber products. Different extraction solvents were studied and influence of the extraction technique and the extraction time were evaluated. Rubber allergens in the extracts were quantified by HPLC using a diod-array detector. The delivery of rubber allergens from the patch test to the skin was determined by analysis of residual allergens in the patch test cup.
Results
By using a strictly non-metallic HPLC-system dithiocarbamates could be analyzed besides the more easily handled thiurams and mercaptobenzothiazoles. We found acetone to be the most appropriate extraction solvent for rubber glove allergens. Analyses of different types of extraction procedures showed shaking to be best. Extraction time was studied by analysis of aliquots at different time. Ten minutes of extraction can be recommended. ZDBC in acetone was applied to the skin in petrolatum and on paper discs. The delivery from the petrolatum preparation was almost complete while only 50 % was delivered from the paper disc.
Conclusion
This study shows that there is a great difference in the extraction capacities between different solvents and also between extraction techniques. An extraction time of ten minutes is enough for the gloves studied here. It is essential to use an appropriate delivery system such as petrolatum vehicle to get the allergen to diffuse into the skin. By following the recommendations given in this work an amount of rubber allergen close to the recommendation given by ICDRG is achieved.
Content last modified: 22 May 2005
