No interaction between aluminium occlusive chambers and thiomersal

Background. Positive patch tests to thiomersal are frequent, but of little relevance. Interaction between aluminium occlusive chambers and the mercury of thiomersal may elicit skin irritation and cause false positive results. Methods. Between January 1998 and May 1999, the patients were simultaneousl y patch tested with aluminium and plastic chambers, Positive skin tests wer e compared. Results. Seventeen Of 213 subjects showed positive tests: 15 with the 2 mat erials, 1 only for the aluminium chamber, 1 for the plastic chamber. Discussion. The results did not differ for the two materials. We concluded that positive reactions observed were not caused by interaction between alu minium and thiomersal.