Geological occurrence, mineralogical characterization, and risk assessment of potentially carcinogenic erionite in Italy

Abstract

Erionite is a zeolite representing a well-known health hazard. In fact, exposure of humans to its fibers has been unequivocally associated with occurrence of malignant mesothelioma. For this reason, a multi-methodological approach, based upon field investigation, morphological characterization, scanning electron microscopy (SEM)/energy-dispersive spectroscopy (EDS) chemical analysis, and structure refinement through X-ray powder diffraction (XRPD), was applied to different samples of potentially carcinogenic erionite from Northern Italy. The studied crystals have a chemical composition ranging from erionite-Ca to erionite-Na and display variable morphologies, varying from prismatic, through acicular and fibrous, to extremely fibrous asbestiform habits. The fibrous samples were characterized by an unusual preferred partition of aluminum (Al) at tetrahedral site T1 instead of tetrahedral site T2. Further, a mismatch between the a-parameter of erionite-Ca and levyne-Ca that are intergrown in the asbestiform sample was detected. This misfit was coupled to a relevant micro-strain to maintain structure coherency at the boundary. Erionite occurs in 65% of the investigated sites, with an estimated quantity of 10 to 40 vol% of the associated minerals. The presence of this mineral is of concern for risk to human health, especially if one considers the vast number of quarries and mining-related activities that are operating in the zeolite host rocks. The discovery of fibrous and asbestiform erionite in Northern Italy suggests the need for a detailed risk assessment in all Italian areas showing the same potential hazard, with specific studies such as a quantification of the potentially respirable airborne fibers and targeted epidemiological surveillance.

Different Erionite Species Bind Iron into the Structure: A Potential Explanation for Fibrous Erionite Toxicity

“…The framework of pristine sample is characterized by <T1-O> and <T2-O> bond distances of 1.6279 Å and 1.6465 Å respectively (Supplementary Material, Table S3) that are only marginally different in the case of the Fe(II) loaded sample possibly owing to protonation [49]. The R = ( ) values, based on the Jones [72] determinative curves, are higher than those arising from the regression equation of Giordani et al [40]. This is possibly due to the extreme sensitivity of those curves from small variations of average T1-O and T2-O distances that may be attributed to the detrimental effects of an imperfect peak-shape modeling in the case of curled fibers [61].…”

“…In Italy, the occurrence of erionite was reported in some areas of Sardinia and Veneto regions [37][38][39]. Recently, Giordani et al [26,40] provided a field description and a detailed mineralogical characterization of selected samples of potentially carcinogenic fibrous erionite discovered in the Lessini Mountains (Veneto region, NE Italy).…”

Malignant Mesothelioma and Its Non-Asbestos Causes

“…18 More recently, erionite has also been identified in North Eastern Italy. 19 Baris and colleagues 20 and Artvinli and Baris 21 first reported an outbreak of mesothelioma in 2 small villages in the Anatolian region of Turkey. Some of the villagers also had chronic fibrosing pleurisy.…”

Real-Time Observation of Fibrous Zeolites Reactivity in Contact with Simulated Lung Fluids (SLFs) Obtained by Atomic Force Microscope (AFM)

“…The exposure of erionite fibres to humans has been unambiguously linked to malignant mesothelioma, and in vivo studies have demonstrated that, at present, erionite is the most carcinogenic mineral [7]. Accordingly, a growing concern has developed regarding the potential health risks associated with environmental and occupational exposures to erionite in different countries, such as Turkey, the USA, Mexico, Iran and Italy [8][9][10][11][12].…”

“…A potential carcinogenic hazard of offretite fibres has neither been confirmed nor dismissed so far and it remains unclear whether the mineralogical distinction between erionite and offretite has any health implications. Recently, the epidemiological, mineralogical and toxicological effects of erionite have been intensively investigated [12,[16][17][18][19][20][21][22][23][24][25]. Studies regarding erionite fibres were conducted on their interacting capability and the interactions with micelles and model membranes [26,27].…”