Paraphenylenediamine sensitivity. Possible cross-sensitization to amines present in rubber.

An indication that paraphenylenediamine (PPD) sensitivity might point to a rubber dermatitis was found in a report by Sidi and Dobkevitch-Morrill (1). These authors described six eases of rubber dermatitis, five of whom showed 1 to 3 plus patch test reactions to PPD. In addition and fairly often, positive patch tests have been obtained to rubber with negative tests to monobenzyl ether of hydroquinone, mereaptobenzothiazole and tetrametbyithiuram monosulfide (2) suggesting the need to look further for the presence of sensitizers in rubber products. This subject was studied by testing six eases, known to be sensitive to PPD with a series of amines used as ingredients of antioxidants in rubber. The positive patch tests to PPD were characterized by pruritus, bright erythema and a button-like induration. Vesicle formation was not evident. Persistence of the positivity for several weeks or longer was a constant feature. All the cases had been patch tested previously with the following test substances: potassium ebromate 1 % aqueous, nickel sulfate 1 % aqueous, mercuric chloride 0.1% aqueous, formaldehyde 1 % aqueous, monobenzyl ether of hydroquinone 1% petrolatum, mercaptobenzothiazole 1% petrolatum, tetramethylthiuram monosulfide 1 % petrolatum, PPD 2% petrolatum, benzocaine 1% petrolatum, rhus resin 0.1% petrolatum, and thiosalicylie acid 0.1% petrolatum. As indications arose, other test substances were included. The PPD sample was renewed about every three months. The over-all preponderance of negative tests makes it unlikely that primary irritation occurred from either fresh or older test samples. Tbe amines tested and their formulas appear in Table 1. They were tested in concentrations of 1 per cent in petrolatum. Twenty-five subjects were patch tested for evidence of primary irritation. No reactions occurred. A number of the amines had been screened by Blank and Miller (3). This assured the testing of substances without using completely unknown chemicals. They recorded one response to phenyl alpha naphthylamine, one to a reaction product of diphenylamine and acetone and one to a butyraldehyde-aniline condensation product. The patients were told in advance