Conversion Between Zinc Diethyldithiocarbamate (ZDEC) and Tetraethylthiuram Disulphide (TETD) Studied in Patch Test Syringes and Porcine Skin

Background: Accelerators in rubber gloves can cause contact allergy. Although rubber gloves mostly contain dithiocarbamates, for example, zinc diethyldithiocarbamate (ZDEC), patients react more frequently to thiurams, for example, tetraethylthiuram disulphide (TETD) in patch testing. Thiurams and dithiocarbamates constitute a redox pair and may thus be converted into each other. Objectives: To investigate whether ZDEC and TETD are converted into each other in patch test syringes and in porcine skin. Methods: ZDEC and TETD patch test syringes were analysed by high-performance liquid chromatography. A Franz diffusion cell model using porcine skin as a membrane was used to investigate the conversion of TETD and ZDEC. Results: All patch test syringes contained the correct rubber accelerator; however, traces of TETD were found in a single ZDEC syringe. On average, 33.2% of the applied ZDEC and 57.4% of the applied TETD were recovered from the Franz diffusion cells. Small amounts of TETD were found in Franz diffusion cells applied with ZDEC (0.16% of the applied ZDEC), but not vice versa. Conclusions: The material in the syringes was stable. Any clear-cut interconversions between TETD and ZDEC could not be demonstrated in this porcine skin model.