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The omnipresence of microplastics (MPs) in marine and terrestrial environments as a pollutant of concern is well established and widely discussed in the literature. However, studies on MP contamination in commercial food sources like salts from the terrestrial environment are scarce. Thus, this is the first study to investigate various varieties of Australian commercial salts (both terrestrial and marine salts) as a source of MPs in the human diet, and the first to detect MPs in black salt. Using Nile red dye, the MPs were detected and counted under light microscopy, further characterised using attenuated total reflectance Fourier transformed infrared spectroscopy (ATR-FTIR) and scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM–EDS). Of all the 90 suspected particles, 78.8% were identified as MPs with a size ranging between 23.2 µm and 3.9 mm. The fibres and fragments constituted 75.78% and 24.22% respectively. Among the tested samples, Himalayan pink salt (coarse) from terrestrial sources was found to have the highest MP load, i.e. 174.04 ± 25.05 (SD) particle/kg, followed by black salt at 157.41 ± 23.13 particle/kg. The average concentration of detected MPs in Australian commercial salts is 85.19 ± 63.04 (SD) per kg. Polyamide (33.8%) and polyurethane (30.98%) were the dominant MP types. Considering the maximum recommended (World Health Organization) salt uptake by adults daily at 5 g, we interpret that an average person living in Australia may be ingesting approximately 155.47 MPs/year from salt uptake. Overall, MP contamination was higher in terrestrial salts (such as black and Himalayan salt) than the marine salt. In conclusion, we highlight those commercial salts used in our daily lives serve as sources of MPs in the diet, with unknown effects on human health. [ABSTRACT FROM AUTHOR]

Introduction: Occupational exposure data on asbestos are limited and poorly integrated in Australia so that estimates of disease risk and attribution of disease causation are usually calculated from data that are not specific for local conditions. Objective: To develop a job-exposure matrix (AsbJEM) to estimate occupational asbestos exposure levels in Australia, making optimal use of the available exposure data. Methods: A dossier of all available exposure data in Australia and information on industry practices and controls was provided to an expert panel consisting of three local industrial hygienists with thorough knowledge of local and international work practices. The expert panel estimated asbestos exposures for combinations of occupation, industry, and time period. Intensity and frequency grades were estimated to enable the calculation of annual exposure levels for each occupation-industry combination for each time period. Two indicators of asbestos exposure intensity (mode and peak) were used to account for different patterns of exposure between occupations. Additionally, the probable type of asbestos fibre was determined for each situation. Results: Asbestos exposures were estimated for 537 combinations of 224 occupations and 60 industries for four time periods (1943-1966; 1967-1986; 1987-2003; ≥2004). Workers in the asbestos manufacturing, shipyard, and insulation industries were estimated to have had the highest average exposures. Up until 1986, 46 occupation-industry combinations were estimated to have had exposures exceeding the current Australian exposure standard of 0.1 f ml−1. Over 90% of exposed occupations were considered to have had exposure to a mixture of asbestos varieties including crocidolite. Conclusion: The AsbJEM provides empirically based quantified estimates of asbestos exposure levels for Australian jobs since 1943. This exposure assessment application will contribute to improved understanding and prediction of asbestos-related diseases and attribution of disease causation. [ABSTRACT FROM AUTHOR]

Wastewater treatment plants (WWTPs) have been identified as an important pathway of microplastics to the environment. Most studies have focused on wastewater effluent, but generally only a small fraction of microplastics entering WWTPs are present in treated effluent. Instead, the majority of microplastics are expected to be retained in the sludge. To our knowledge, there is limited information on microplastics in sludge/biosolids from Australian WWTPs, despite 75% of biosolids produced in Australia being used for agriculture. This study evaluated the abundance of microplastics throughout the treatment trains of three WWTPs in Australia. The fate of microplastics >25 μm during treatment and their release to the environment was evaluated using an audit approach. The highest microplastic concentrations were detected in the influent, with fibres the dominant form of microplastic found. The screening and grit removal process preceding primary treatment removed 69–79% of microplastics, with these microplastics transported to landfill. Only 0.2–1.8% of the total microplastics in the influent were present in the final effluent, while 8–16% were retained in biosolids. This equates to between 22.1 × 106 to 133 × 106 microplastic particles per day released in effluent, between 864 × 106 to 1020 × 106 microplastic particles per day in biosolids, and between 4100 × 106 to 9100 × 106 microplastic particles per day transported to landfill. This study shows for the first time that most microplastics are retained during the initial screening and grit removal process with the load of microplastics going to landfill an order of magnitude greater than that in biosolids. Landfills may thus be an important sink (and potential future source) of microplastics from wastewater. Image 1 • An audit approach was applied to three WWTPs to evaluate microplastic fate. • Screening and grit removal removed up to 79% of microplastics entering the WWTP. • Removed microplastics transported to landfill, showing it is a microplastic sink. • Up to 2% and 16% of microplastics released in effluent and biosolids, respectively. [ABSTRACT FROM AUTHOR]