Nano- and microplastics in the workplace
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Abstract
The on-going COVID-19 pandemic has resulted in a dramatic increase in the use of N95 respirators, barrier face coverings, disposable gloves, gowns, and other measures to control the spread of SARS-CoV-2. For example, population-based estimates suggest that over seven billion facemasks, which translates to 21,000 tons of synthetic polymer, are used daily in the world in response to the COVID-19 pandemic (Hantoko et al. 2021). After use, these products end up in the synthetic polymer environmental waste stream and contribute to the growing problem of plastic pollution at an estimated rate of about 40% of plastic demand (Lau et al. 2020). Plastic litter in the environment breaks down to plastic fragments, which have been found in air, water, and food (Gigault et al. 2018; Mitrano 2019; Lim et al. 2021). Small particles of plastics are often referred to as microplastics (plastic particles with any dimension between 1 micrometer and 1,000 micrometers [ISO 2020]) and nanoplastics (plastic particles smaller than 1 micrometer [ISO 2020]). Polyethylene and polypropylene are the most commonly found types of plastic in aquatic environments and soil matrices (Yang et al. 2021). Nanoand microplastics (NMP) can be formed incidentally through environmental and mechanical degradation. Incidental NMP can be also generated through condensation of molecular species, for example, during heating or burning of plastics. Different pathways for generation of these particles produces incidental NMP of varying morphology and chemical composition, thus leading to varying biological activity ranging from activation of transient inflammatory response and interference with physiological functions to immunosuppression and carcinogenesis (Huaux 2018; Prata 2018). Manufactured NMP can be made intentionally for use in industrial processes, for example, as feedstock for powder-bed and multi-jet fusion 3D printers. Human exposure to NMP particles through inhalation and ingestion has raised concerns about their potential adverse health effects and has led to calls for monitoring the environment and food for plastic pollution (Alexy et al. 2020). At the 2019 Global Summit on Regulatory Science, regulatory bodies from ten countries identified a number of knowledge gaps, including a lack of suitable and validated analytical methods for sampling, identification and quantification of NMP and paucity of hazard and fate data, which hinders regulatory risk assessments (Allan et al. 2021). Since 2019, progress has been achieved in developing new analytical techniques for characterization of NMP in different environmental media (Castelvetro et al. 2021; Velimirovic et al. 2021; Yang et al. 2021). This paper discusses potential health hazards and exposure mitigation to NMP in the workplace, along with a description of recent work being conducted by NIOSH.