[Hypersensitivity to rubber]

Occupational contact dermatitis caused by rubber chemicals is described in two groups of patients. The first group consisted of personnel from the operating rooms of a university hospital. In 12 persons the contact allergic reactions appeared to be mainly due to rubber chemicals of the thiuram group of compounds. The second group consisted of cattle farmers. In 6 persons patch tests could be performed. The main cause of the rubber contact on the farms appeared to be the milking machine. The antioxydants in the heavy duty rubber of these machines are of the paraphenylenediamine group of compounds. Positive patch tests were found to N-phenyl-N' -cyclohexylparaphenylenediamine (CPPD) and to the closely related N-phenyl-N'-isopropylparaphenylenediamine (IPPD). Their use in rubber of milking machines in Europe is based on the german "Mitteilungen aus dem Bundesgesundheitsamt" which permits the incorporation of IPPD in these kind of rubber parts to a percentage of 1,5%.