Metal Ion Release from Engineered Stone Dust in Artificial Lysosomal Fluid—Variation with Time and Stone Type

Abstract

Inhalational exposure to dust from engineered stone (ES), also known as artificial or composite stone, is associated with a specific disease profile, namely accelerated silicosis, and scleroderma. The pathogenic mechanisms are poorly understood, particularly the role of resin and metal ions. Metal ions are present in pigments and constituent minerals and may be considered potential contributors to toxicity. The aim of this preliminary study was to understand the solubility of ES-containing metals in artificial lysosomal fluid (ALF) simulating the acidic intracellular environment of the lung macrophage lysosome. Differences with respect to ES types and temporal release were explored. Ten ES products of variable colour and company origin were comminuted and assessed for four different metals, solubilized into ALF solutions at 1,2,4 and 8 weeks at 37 °C. There was significant variability in metal release, particularly with regard to iron and manganese, which could be correlated with the reflected brightness of the stone. A majority of the available Mn, Fe, Al and Ti was solubilized. Time trends for metal release varied with ES type but also with metal ion. The data suggest a high metal ion bioavailability once engulfed by lung macrophages. There is a need to investigate a wider range of ES dust and relate metal content to markers of ES toxicity.

Compositional and structural analysis of engineered stones and inorganic particles in silicotic nodules of exposed workers

“…One of our countertops samples (M2) contained 2.5% Aluminum (Al is contained in more complex albite compound), and Di Benedetto detected Al in all samples tested [ 12 ]. Aluminum, described as an elemental solid or as part of compounds or minerals, has been reported in other countertop samples [ 3 , 13 , 32 ].…”

“…Although some researchers have studied the mineralogical and metallic composition of countertops, their organic components have only been partially studied [ 3 ]. This organic content can represent up to 14.3 wt.% of ES [ 32 ].These compounds are part of the resins used in manufacturing and reach the lungs as part of the dust particles inhaled during the working processes (cutting, drilling, polishing, etc.). Recently, Halls and colleagues have detected measurable concentrations of a wide range of VOCs emitted when cutting ES [ 42 ].…”

What Do Safety Data Sheets for Artificial Stone Products Tell Us About Composition? A Comparative Analysis with Physicochemical Data

“…S1 , available at Annals of Work Exposures and Health online). This may relate to colour differences across products ( Maharjan et al , 2021 ).…”

“…The samples were then crushed to gravel size using a tungsten carbide jaw crusher. These pieces were subsequently comminuted under moderate conditions, to a mid-point size distribution of 10–18 µm, as described in Maharjan et al (2021) .…”

“…Assessment of physicochemical properties of the AS samples, excluding organic resin, were determined by external National Association of Testing Authorities, Australia (NATA)-accredited laboratories ( Maharjan et al , 2021 ). Absolute metal content was determined by X-ray fluorescence (XRF) and crystalline mineral content was determined by X-ray diffraction (XRD), with a precision value at 0.001% and 1% by weight, respectively.…”