Occupational asthma caused by palladium

Occupational exposure to complex platinum salts is a well-known cause of occupational asthma. Although there is evidence that platinum refinery workers may also be sensitized to other precious metals, such as palladium or rhodium, no instances of occupational asthma due to an isolated sensitization to palladium have been reported. A case is reported of occupational rhinoconjunctivitis and asthma in a previously healthy worker exposed to the fumes of an electroplating bath containing palladium. There was no exposure to platinum. Sensitization to palladium was documented by skin-prick tests. The skin-prick test was positive with Pd(NH3)4Cl2, but not with (NH4)2PdCl4. Corresponding salts of platinum were all negative. A bronchial provocation test with Pd(NH3)4Cl2 (0.0001% for a total of 315 s, followed by 0.001% for a total of 210 s) led to an early decrease in forced expiratory volume in one second (-35%). A similar exposure (0.001% for a total of 16 min) in an unrelated asthmatic gave no reaction. This case shows that an isolated sensitization to palladium can occur and that respiratory exposure to palladium is a novel cause of metal-induced occupational asthma.