Cross-reactivity between thiurams.

Retesting with an allergen at a site with previous allergic contact dermatitis has been shown to enhance reactivity. It has been suggested that retesting with a cross-reactive allergen will also induce hyperreactivity. Concurrent sensitization to more than 1 thiuram is common, but whether this is due to concomitant primary sensitization or cross-reactivity is uncertain. The aim of this study was to investigate the use of retesting to distinguish between concomitant sensitization and cross-reactivity in the rubber chemicals tetraethylthiuram disulphide (TETD) and tetramethylthiuram disulphide (TMTD). There was a non-significant trend towards enhanced reactivity for both TETD and TMTD when testing in an area with previous allergic contact dermatitis due to TETD. Cross-reactivity between the 2 chemicals is likely, but a definite conclusion from this pilot study is not possible.