ETHYLMERCURIC CHLORIDE - THE RESPONSIBLE AGENT IN THIMEROSAL HYPERSENSITIVITY

The causative agent of thimerosal allergy (sodium ethylmercury thiosal icylate) has not previously been thoroughly investigated. To evaluate whether the organic mercury component or the thiosalicylic acid molecu le induces thimerosal sensitization, 23 patients positive to thimerosa l were patch tested with ethylmercuric chloride, thiosalicylic acid an d 8 different derivatives of mercury. To date, ethylmercuric chloride has not been tested in thimerosal allergy. 19/23 patients (82%) showed positive patch test reactions to ethylmercuric chloride. 4/23 patient s negative to ethylmercuric chloride reacted positively to thimerosal 0.1% but not to thimerosal 0.05%. 8/23 patients (35%) also reacted to other mercurials. 20 controls negative to thimerosal showed negative p atch test reactions to ethylmercuric chloride. Neither patients nor co ntrols reacted to thiosalicylic acid. These results indicate that test ing with thimerosal 0.1% leads to false-positive reactions and that th e ethyl mercury component is the responsible agent in thimerosal aller gy.