Erionite is a species belonging to the group of zeolites, minerals found mainly in volcanic rocks and widely used in various fields, from construction to agriculture. Although zeolites, in general, are not harmful to humans, erionite, on the contrary, possesses a high degree of inhalation toxicity, hundreds of times higher than that of asbestos. In the 1970s, erionite was the cause of an epidemic of malignant pleural mesothelioma (MPM) in some villages in Cappadocia, where homes were built with materials containing this mineral.

A joint study between Sapienza University of Rome, University of Genoa and ENEA, conducted as part of the EU-funded RETURN Extended Partnership - NextGenerationEU, recently published in the international Journal of Hazardous Materials, investigated the mechanisms underlying the toxicity of erionite, which to date have remained unclear.

Using an innovative interdisciplinary approach, the research analysed the structural and chemical changes that occur in the mineral fibres once they are phagocytosed by the macrophage cells present in the lungs and responsible for the internalisation and destruction of foreign substances.

The study found that when erionite fibres are phagocytosed by macrophage cells, the immune system's ‘scavengers’, they trigger an ion exchange that causes the pH to rise and the lysosomes, the cellular organelles responsible for degrading foreign bodies, to malfunction.

‘The complex process of ion exchange,’ says Paolo Ballirano, lecturer at Sapienza, ‘was revealed through powder X-ray diffraction experiments conducted at the laboratories of the Department of Earth Sciences of Sapienza University of Rome on quantities of fibres on the order of fractions of a milligram, recovered from inside the cells after various incubation times ranging from a minimum of 24 hours to a maximum of 14 days’.

‘Raising the cellular pH,’ says Sonia Scarfì, lecturer at the University of Genoa, ‘also causes a high energy demand, which is met by hyperactivation of the mitochondria, the cell's energy centre. The result of this hyperactivation a few days after phagocytosis is an increase in the production of oxygen radicals in the mitochondria and, subsequently, mitochondrial distress that can lead to cell death'.'Given the remarkable chemical stability of erionite in biological fluids, this mechanism leading to cell death can potentially repeat itself indefinitely: as a matter of fact, erionite, once released again into the extracellular environment, is able to regain its toxic potential. It follows,' Ballirano and Scarfì conclude, ’that this phenomenon leads to chronic inflammation and the potential development of cancer'.

References

Paolo Ballirano, Alessandro Pacella, Serena Mirata, Mario Passalacqua, Maria Cristina Di Carlo, Lorenzo Arrizza, Maria Rita Montereali, Sonia Scarfì, “Fibrous erionite modifications following THP-1 macrophage phagocytosis: An insight into the mechanisms of interaction with biological systems”, Journal of Hazardous Materials, 2025, 489:137646, https://doi.org/10.1016/j.jhazmat.2025.137546

Further Information

Paolo Ballirano

Department of Earth Sciences

paolo.ballirano@uniroma1.it