Role of Associated Mineral Fibres in Chrysotile Asbestos Health Effects: The Case of Balangeroite

OBJECTIVES: To evaluate the biodurability of balangeroite, present as contaminant of chrysotile asbestos in the Balangero mine, in order to have indication whether it might have been a confounding factor in the association of the mesothelioma cases reported among mine workers and employees. METHODS: The modifications taking place following incubation of the fibres in simulated phagolysosomal fluids have been measured on balangeroite, on one pure chrysotile sample (Val Malenco), on one chrysotile from Balangero with some associated balangeroite, and on two tremolite samples. RESULTS: The incubation modifies both chrysotile and balangeroite with substantial release in the medium of the metal ions which occupy the octahedral site in the mineral structure of the fibre while tremolite is virtually unaffected. CONCLUSIONS: Considering the profound differences between the structure of balangeroite and amphiboles, previous results and observations on the poor ecopersistence of balangeroite, and the present data, we conclude that balangeroite traces may contribute to the overall toxicity of the airborne fibres in Balangero, but may not be compared to tremolite nor considered the sole responsible for the excess of mesothelioma found in Balangero.