20 years of medical surveillance on exposure to allergenic and non-allergenic platinum compounds: the importance of chemical speciation

Objectives-Chloroplatinates are patent allergens but other soluble platinum compounds such as tetraammine platinum dichloride (TPC) do not provoke rea ctions in subjects who are sensitive to chloroplatinates, TPC has been used in the manufacture of autocatalysts for 20 years. This study analyses 20 y ear data on exposure to soluble platinum compounds and medical surveillance to confirm that TPC is not allergenic. Methods-Workers in three distinct operations were exposed to soluble platin um compounds as chloroplatinates, chloroplatinates with TPC, or to TPC alon e. Results of personal air sampling for soluble platinum compounds were com pared together with the results of medical surveillance. Results-The levels of exposure to soluble platinum compounds in each operat ion were comparable but the incidence of allergy was significantly differen t. In a subgroup of workers consistently exposed to chemical processes in e ach operation, the cumulative chance of being sensitised after 5 years of e xposure was estimated as 51% for chloroplatinate exposure, 33% for mixed ex posure, and 0% for TPC alone. The differences in sensitisation rates could not be explained by age, sex, and atopy. Nor could they be explained by the increased frequency of smoking in the workers with chloroplatinate exposur e, despite the markedly higher risk of sensitisation in smokers. The differ ences could only be explained by the chemical stability of TPC. Conclusions-This study shows that the soluble platinum compound TPC is not allergenic under normal industrial conditions. Characterisation of the chem ical compound (speciation) is essential to prevent stringent exposure limit s being imposed for all soluble compounds on a generic basis.