Contact urticaria in a child from raw potato

Polyisobutylene is the polymer of isobutylene, a longchain aliphatic hydrocarbon. There are several types with differing molecular weights. The polyisobutylene in question has a relative molecular mass of 85,000 (Oppanol B 15). Other than the stabilizer, this can be considered to be pure polyisobutylene. The ash content is less than 100 ppm and most of the ash contains the oxides and silicates of iron, potassium and sodium. The total heavy metal content is < 1 ppm. The stabilizer is 2,6-di-tertbutyl-4-methylphenol (BHT), at a concentration of 400 ppm, which prevents oxidation. The patient tested negative to BHT on patch testing. This polyisobutylene is a synthetic rubber, a constituent of all hydrocolloids and also chewing gum. As far as we know, all stoma appliances contain polyisobutylene. It gives a hydrocolloid its dry adhesion to skin, the wet adhesion to mucous membranes being supplied by a pectin. The other components of hydrocolloids usually include a thickening agent, such as sodium carboxy methyl cellulose and gelatin to support the matrix. Irritant reactions to stoma appliances and drainage fluid are common ( 1 ), but allergic reactions are rare. Contact Dermatitis 1996: 35: 179