Bioavailability of rubber accelerators in rubber gloves and patch test reactivity

The aim of this study was to investigate the clinical relevance of determination of the total amounts of residual accelerators in rubber gloves, using a previously described analytical procedure. As a measure for clinical relevance, patch test reactivity to glove material was used. Results from analyses of'the gloves were compared to patch test reactions performed with the identical glove materials in 40 unselected thiuram- or mercaptobenzothiazole-sensitised patients. A high correlation between patch test results to glove material and acetone extracts of the same material was found, indicating that acetone was a relevant extraction medium for qualitative analysis. The outcome of the patch tests performed with the glove material in the individual patients was predicted, based on the sensitivities diagnosed in the patient and the chemicals found to be present in the extracts. Positive tests were hereby predicted in 72 % and negative tests in 60 %. These predictive values were identical to values obtained with manufacturers ingredient declarations as information source. Prediction of the outcome of the patch tests in the patients was more correct, when cross-reactivity between derivatives with identical amino-groups was anticipated, than when no cross-reactivity at all between thiuram-and carbamate-derivatives was expected. A direct correlation between the total amounts of rubber accelerators present in the extracts and the number of patients with positive patch test reactions to the corresponding glove material was not found, possible due to great variability in patterns of sensitivities in the patients, cross-reactivity between different constituents, and diversity of allergens present in the gloves. There was a tendency to separation of the glove materials into two groups with low and high content of accelerators, respectively, released to the extract. The group of gloves with low content tended to give few reactions in the patients and gloves with a high content to give many reactions. The present use by some manufacturers, referring to the total amount of rubber accelerators in acetone or aqueous extracts as a measure for sensitising capability of the rubber material, could not be supported directly by this study, but it is possible that a further refinement of the extraction procedure may lead to a procedure which reflects the allergologically relevant, bioavailable amounts better that this assay. This will require further kinetic studies and studies of penetration of the accelerators into the human skin. It is expected, however, that both quantitative as well as qualitative modalities of the chemical residuals in the gloves have to be taken into account, when the sensitising capability of rubber gloves is studied.