Unveiling the Interaction Mechanisms of Asbestiform Minerals with Simulated Lung Fluids and Their Influence on Chemical Reactivity

Asbestos is a group of naturally occurring mineral fibres classified as Group 1 carcinogens. Its most significant carcinogenic effects occur through inhalation; however, the molecular mechanisms underlying asbestos-related lung diseases remain unclear. To date, aspect ratio, surface reactivity, and biopersistence are widely recognised as key factors influencing the pathological response to asbestos [1]. This study investigates the behaviour of different asbestiform minerals interacting with two simulated lung fluids (SLFs): artificial lysosomal fluid (ALF), which mimics the lysosomal environment within macrophages, and Gamble’s solution, which simulates the interstitial fluid [2]. Dissolution processes, surface chemical modifications induced by interaction with these fluids, and the impact of these alterations on the chemical reactivity of mineral fibres were thoroughly examined. We considered both amphibole and serpentine asbestos. Specifically, we analysed a UICC crocidolite sample from South Africa, a fibrous tremolite sample from Basilicata, Italy, and a UICC chrysotile sample from Zimbabwe. Additionally, a fibrous antigorite sample from Calabria, Italy, was included in the study. The samples were incubated in the two SLFs for up to 28 days at T = 37 ± 1 °C. Fibre dissolution was measured by inductively coupled plasma optical emission spectrometry (ICP-OES). X-ray photoelectron spectroscopy (XPS) was used to detect modifications of the surface chemical composition following dissolution. In particular, changes in iron speciation were correlated with the chemical reactivity of both pristine and incubated fibres, measured as the release of •OH radicals. The catalytic activity was assessed in the presence of H2O2 for up to 15 days, using the spin-trapping technique coupled with electron paramagnetic resonance (EPR) spectroscopy. Our findings revealed that the two SLFs induce different dissolution mechanisms on the fibres, resulting in distinct surface chemical modifications. Fibre reactivity is strongly influenced by both interaction with these fluids and the minerals’ crystallochemistry, providing new insights into the toxicity mechanisms associated with the Fenton reaction involving iron ions on fibres. [1] IARC (2012), IARC Monographs on the Evaluation of Carcinogenic Risks to Humans 100(PT C), 11. [2] Marques, Loebenberg & Almukainzi (2011), Dissolution Technologies 18(3), 15–28.