Elettra | TwinMic A closer look at the toxicity mechanisms of erionite, one of the major natural carcinogens Erionite is a natural mineral that looks harmless at first glance. Its soft, woollike appearance and delicate fibres don’t suggest any immediate danger. Yet, this seemingly innocent mineral hides a serious health threat. When its fine fibres become airborne and are inhaled, they can penetrate in the lungs and remain there for decades. Over time, this accumulation significantly increases the risk of developing mesothelioma, a rare and aggressive form of cancer affecting the lining of the lungs and other organs. Erionite belongs to the zeolite family, a group of minerals characterized by their unique porous structures. These micropores enable zeolites to trap water and exchange chemical elements, which is why they have found widespread use in numerous industrial applications, including water purification, catalysis, and gas absorption. Despite these useful properties, erionite’s fibrous form presents a starkly different picture. Unlike its bulk form, fibrous erionite poses severe health hazards when inhaled, primarily due to its size, shape, and chemical stability. The dangers of erionite were first discovered in the small villages of Cappadocia, Turkey, where the natural presence of this mineral exposed residents to unusually high rates of mesothelioma. These epidemiological findings led to the International Agency for Research on Cancer (IARC) classifying fibrous erionite as a Group 1 carcinogen, placing it alongside asbestos, the well-known hazardous mineral linked to lung disease and cancer. So, what makes erionite so deadly? The mineral exhibits a property called bio-persistence, meaning that once inhaled, its fibres do not easily break down or clear from the lungs. Instead, they remain in the lung tissue for many years. This prolonged presence can cause chronic inflammation, leading to a potentially lethal biological cascade that increases cancer risk. Another important factor is erionite’s ability to exchange ions within the body’s environment, a trait that scientists have long suspected contributes to cellular damage and malignancy. A study by an international team led by Italian researchers is shedding new light on the deadly mechanism of this mineral. This research, carried out by scientists from Elettra Sincrotrone Trieste, several Italian universities (Universities of Modena and Reggio Emilia, Genoa, and Parma) and the National Research Council, used cutting-edge synchrotronbased techniques to visualize erionite’s interaction with immune cells at an unprecedented resolution. By employing soft x-ray microscopy and low-energy sub-μ X-Ray Fluorescence (XRF) mapping was performed at the TwinMic beamline of Elettra Sincrotrone Trieste to monitor Na, Mg, Fe, O, and C distribution in the cells. The measurements were complemented at ID21 beamline of European Synchrotron (ESRF, Grenoble, France) at higher energy to follow Ca, Cr, K, Fe, Al, Si, P, and S distribution on the same cells. Control (non-exposed cells) were compared to cells exposed to 50 μg/ml erionite fibres for 8, 24 and 96 hours. Isolated geological erionite fibres alone were also analysed to investigate the elemental distribution independently from cells. The study mapped erionite’s toxic timeline in unprecedented detail. Remarkably, within just eight hours, the smallest mineral fibres had penetrated macrophages. By 24 hours, even longer fibres were internalized, and after 96 hours, nearly all fibres had entered the cells, leaving none outside. During this process, sodium ions gradually leached from the fibres while magnesium ions remained tightly bound, highlighting complex chemical interactions (Fig. 1). Erionite does not simply remain confined to the lungs. It interacts with cells, causing stress and carrying harmful materials such as iron particles. The mineral’s fibres exhibit the ability to move beyond the lungs towards the pleural membrane, they actively interfere with cellular systems and create stress responses. Once ingested by immune cells, erionite fibres disrupt the internal ionic balance of these cells, particularly the balance between calcium and sodium. This imbalance acts as a trigger for cellular stress and may initiate the pathological changes that eventually lead to cancer. One of the study’s most surprising discoveries was that erionite’s previously assumed primary toxic mechanism - its ion-exchange capability - plays a less dominant role than once thought. Instead, tiny iron-rich particles attached to the mineral fibres appear to drive much of its carcinogenic potential. These iron particles enhance oxidative stress within macrophages, damaging cellular components and potentially fostering a microenvironment that promotes cancer development. This novel insight helps explain why erionite could be even more harmful than asbestos. These findings deepen our understanding of mineral fibre toxicity and underscore the complexity of how natural minerals can impact human health. They also open new avenues for developing strategies to mitigate harm after exposure to hazardous mineral fibres. As research advances, such knowledge will be crucial for protecting individuals working in environments where erionite or similar minerals are present, as well as for informing public health policies in affected regions worldwide. In conclusion, while erionite may appear innocuous on the surface, its hidden dangers are profound. Continued scientific investigation and awareness are essential to safeguard communities and workers from the long-term health risks posed by this silent mineral threat. Elettra Highlights 2024–2025 64
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