PARAMETERS WHICH DETERMINE THE ACTIVITY OF THE TRANSITION-METAL IRON IN CROCIDOLITE ASBESTOS - ESR, MOSSBAUER SPECTROSCOPIC AND IRON MOBILIZATION STUDIES

The transition metal iron, present in crocidolite asbestos fibres, red uces oxygen and participates in a Fenton-type reaction. Because of the importance of these reactions in crocidolite-induced toxicity, studie s have been conducted on three different types of crocidolite fibres t o determine the factors which control the activity of iron in catalysi ng the two reactions. Results show that the total concentration of iro n in crocidolite fibres is not a good parameter for characterizing the activity of this mineral, which seems rather to be controlled by the valency and location of iron in the lattice, and also by its availabil ity for mobilization from these minerals.