Acicular berthierine-chamosite in coal and lung cancer tissues of Xuan Wei, China

Xuan Wei has China's highest female lung cancer mortality, attributed to household coal smoke exposure. While coal-derived polycyclic aromatic hydrocarbons (PAHs) were previously blamed, persistently rising lung cancer rates despite PAH reductions implicate other carcinogens. Here, we aim to investigate iron-rich minerals in Late Permian coal as potential overlooked drivers. Coal was sampled from Laibin, epicentre of Xuan Wei lung cancer epidemic. Mineral phases in low temperature ash (LTA) were characterized by X-ray diffraction (XRD) along with selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (TEM). Mineral morphology and elemental composition were examined by scanning electron microscope (SEM) and TEM equipped with energy-dispersive X-ray spectrometer (EDS). Lung tissues from 10 patients (5 female, 5 male) were examined for mineral deposition by SEM and TEM. We identified acicular iron-rich interstratified berthierine-chamosite minerals coating quartz/calcite in coal. Berthierine shares the serpentine group classification with chrysotile (i.e., white asbestos, a known human carcinogen). We observed abundant berthierine-chamosite needles in cancerous and para-cancerous lung tissues, with iron leaching from the berthierine-chamosite into acidic digestive vacuoles and accumulating in holo-ferritin and hemosiderin aggregates within autolysosomes. Given its much higher iron content than chrysotile, this needle-like berthierine-chamosite in Late Permian coal could be more bioactive and toxic, potentially driving the lung cancer epidemic in Xuan Wei, China. Our findings call for closer collaboration between mineralogists and health scientists for future research to gain deeper mechanistic insights and formulate intervention strategies.