Asbestos and Zeolites: from A to Z via a Common Ion

Abstract

Asbestos and zeolites are silicate-based minerals, linked inextricably via paradoxical similarities and differences which have emanated from different geological epochs. Both have been employed in the service of humanity through millennia: asbestos, for its “inextinguishable” quality of being an insulator against heat and fire; zeolite, a “boiling stone” with its volcanic and marine sedimentary rock origins, for its propensity to adsorb water and remove metals and toxins. Serious adverse health effects observed in asbestos miners as long ago as the 1st Century AD did not halt the rising popularity of asbestos. As the miracle material of the 1900s, asbestos production and consumption exploded, culminating in its ubiquity in ships, vehicles, homes, commercial buildings, and over 3000 different industrial and household products. Through the 1940s and 1950s, epidemiological studies concluded that asbestos was a likely cause of asbestosis, lung cancer, and malignant mesothelioma, and it is now banned in many but far from all countries. The long latency between exposure to asbestos and the occurrence of cancer has obscured the deadly consequences of asbestos exposure for centuries. Even today, a considerable part of the world population is insufficiently aware of the dangers of asbestos, and millions of tons of this carcinogen continue to be mined and used worldwide. Zeolites, both natural and synthetic, are microporous aluminosilicate minerals commonly used in a myriad of processes, in the petrochemical industry, in domestic appliances and cleaning agents, as commercial adsorbents and exchangers for toxins and pollutants, and as catalysts. Zeolites are found in agriculture, veterinary science, and human health. More recently, new materials such as carbon nanotubes are being employed in materials requiring durability and thermal and electrical conductivity, yet nanotubes are now joining the ranks of more established particulates such as asbestos and silica, in causing human disease. In this review, we compare and contrast the similarities and differences of these two groups of silicate minerals and their waxing and waning use in the employ of humanity.

Global geological occurrence and character of the carcinogenic zeolite mineral, erionite: A review

“…Biopersistence is the amount of time the mineral fibers reside within the human body following inhalation, and fibers that cannot be cleared from the respiratory tract are considered biopersistent and can therefore accumulate during chronic exposure (e.g., Bernstein et al, 2005). Erionite fibers exhibit biopersistence, and erionite-induced mesotheliomas have similar histology and long latency to those originating from asbestos, though there are still uncertainties in their respective mechanisms of carcinogenicity (Reid et al, 2021). Two key components of erionite biopersistence are 1) biodurability and 2) dissolution in surfactant or physiological fluids (Moolgavkar et al, 2001).…”

“…In addition to needle-like particle morphology and biopersistence, a key factor contributing to the toxicity potential of erionite has historically been deemed to be the presence of iron (e.g., Fubini and Mollo, 1995). Indeed, it is believed that the toxicity of erionite is linked to both its fibrous properties and its association with iron in natural deposits (Fach et al, 2003;Sanchez et al, 2009;Reid et al, 2021). One theory is that the toxicity of erionite is associated with iron that accumulates on the surface of the fibers and generates cytotoxic hydroxyl radicals (Fach et al, 2003;Waris and Ahsan, 2006;Pacella et al, 2018).…”

“…Zeolites are volcanic in origin and are formed by the action of alkaline water or seawater on volcanic glass in sediments and clays. Of the more than 40 known zeolites, clinoptilolite is the most abundant in nature, followed by analcime, chabazite, heulandite, natrolite, phillipsite, mordenite, stilbite, and erionite (Reid et al, 2021). Zeolites have a very large internal surface area resulting from the particular configuration of their crystalline lattice.…”