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Engineered stones are novel construction materials associated with a recent upsurge in silicosis cases among workers in the stonemason industry. In order to understand the hazard for the short latency of lung disease among stonemasons, we simulated real-time dust exposure scenario by dry-machining engineered stones in controlled conditions, capturing and analysing the respirable dust generated for physical and chemical characteristics. Natural granite and marble were included for comparison. Cutting engineered stones generated high concentrations of very fine particles (< 1 µm) with > 80% respirable crystalline silica content, in the form of quartz and cristobalite. Engineered stones also contained 8–20% resin and 1–8% by weight metal elements. In comparison, natural stones had far lower respirable crystalline silica (4- 30%) and much higher metal content, 29–37%. Natural stone dust emissions also had a smaller surface area than engineered stone, as well as lower surface charge. This study highlighted the physical and chemical variability within engineered stone types as well as between engineered and natural stones. This information will ultimately help understand the unique hazard posed by engineered stone fabrication work and help guide the development of specific engineering control measures targeting lower exposure to respirable crystalline silica.

Fungal contamination in indoor environments has been associated with adverse health effects for the inhabitants. Remediation of fungal contamination requires removal of the fungi present and modifying the indoor environment to become less favourable to growth.  This may include treatment of indoor environments with an antifungal agent to prevent future growth. However there are limited published data or advice on chemical agents suitable for indoor fungal remediation. The aim of this study was to assess the relative efficacies of five commercially available cleaning agents with published or anecdotal use for indoor fungal remediation. The five agents included two common multi-purpose industrial disinfectants (Cavicide® and Virkon®), 70% ethanol, vinegar (4.0%−4.2% acetic acid), and a plant-derived compound (tea tree (Melaleuca alternifolia) oil) tested in both a liquid and vapour form. Tea tree oil has recently generated interest for its antimicrobial efficacy in clinical settings, but has not been widely employed for fungal remediation. Each antifungal agent was assessed for fungal growth inhibition using a disc diffusion method against a representative species from two common fungal genera, (Aspergillus fumigatus and Penicillium chrysogenum), which were isolated from air samples and are commonly found in indoor air. Tea tree oil demonstrated the greatest inhibitory effect on the growth of both fungi, applied in either a liquid or vapour form. Cavicide® and Virkon® demonstrated similar, although less, growth inhibition of both genera. Vinegar (4.0%–4.2% acetic acid) was found to only inhibit the growth of P. chrysogenum, while 70% ethanol was found to have no inhibitory effect on the growth of either fungi. There was a notable inhibition in sporulation, distinct from growth inhibition after exposure to tea tree oil, Virkon®, Cavicide® and vinegar. Results demonstrate that common cleaning and antifungal agents differ in their capacity to inhibit the growth of fungal genera found in the indoor air environment. The results indicate that tea tree oil was the most effective antifungal agent tested, and may have industrial application for the remediation of fungal contamination in residential and occupational buildings.

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Rhizoremediation involves the breakdown of contaminants in soil resulting from microbial activity that is enhanced in the plant root zone. The objective of this study was to identify Australian native grass species as suitable candidates for rhizoremediation application. Seeds of nine perennial Australian native grasses were sown in soil from a mine site and artificially contaminated with a 60:40 diesel/oil mixture at concentrations of 1% (w/w), 0.5% (w/w), and 0% (control). Seedling emergence was not adversely affected by the presence of hydrocarbon contamination for all but one grass species. Three promising species (Brachiaria decumbens, Cymbopogon ambiguus, and Microlaena stipoides var. Griffin) were assessed for growth characterization in contaminated and uncontaminated soils. The evaluated species survived for 120 days in the contaminated soil and, in some instances, produced considerably more root biomass in the presence of contamination. C. ambiguus showed growth stimulation in the presence of contamination (1% and 0.5% w/w) with significantly increased root biomass production compared with the control (p = 0.0001). B. decumbens and M. stipoides showed tolerance, without adverse growth effects in the presence of diesel/oil at the exposed concentrations. Stimulation of the rhizosphere microbial population that is capable of degrading diesel/oil was found for all of the species tested, using a most probable number method for enumeration. This investigation has identified suitable candidates for further investigation of their rhizoremediation potential.