Identification method of asbestiform mineral particles and cleavage fragments in the lung: Regulated and unregulated amphiboles.

Asbestos fibers are well-established causes of lung and pleural diseases. However, the role of other non-asbestiform elongate mineral particles (EMPs) in these conditions remains unclear. This study aimed to assess the feasibility of detecting exposure to EMPs, including non-asbestiform cleavage fragments, in individuals working in industries such as mining, quarrying, public works, construction, and agriculture, by analyzing the mineral lung burden. The study involved lung biopsies from 25 individuals: 20 with lung cancer and 5 with other lung diseases, all of whom had worked in the aforementioned sectors and had an asbestos body (AB) concentration greater than 1000 AB/g of dry lung tissue, the reference value above which ABs concentrations correspond to a non-trivial exposure to asbestos. An analytical protocol was developed to distinguish asbestiform fibers (both basal and apical parts) from two types of non-asbestiform cleavage fragments for both the coated and uncoated particles. Collected asbestos bodies (ABs) were treated with oxalic acid to partially dissolve their ferruginous coating, allowing for visual observation, crystallographic characterization, and chemical analysis via transmission electron microscopy (TEM). Results showed 44 amosite asbestos bodies, 3 crocidolite bodies, 1 ferro-actinolite body, and 6 grunerite non-asbestiform ferruginous bodies. Among 376 regulated and unregulated amphibole particles analyzed both coated and uncoated, 252 were asbestiform, 119 were cleavage fragments, and 5 were undetermined. Given the diversity of particle origins observed, their surface properties likely vary, which may influence their toxicity. It would therefore be important to include these particles in future studies of the mineral lung burden.