Reports of plastics, at higher levels than previously thought, in the water that we
drink and the air that we breathe, are generating considerable interest and
concern. Plastics have been recorded in almost every environment in the
world with estimates on the order of trillions of microplastic pieces. Yet, this
may very well be an underestimate of plastic pollution as a whole. Once
microplastics (<5 mm) break down in the environment, they nominally enter
the nanoscale (<1,000 nm), where they cannot be seen by the naked eye or
even with the use of a typical laboratory microscope. Thus far, research has
focused on plastics in the macro- (>25 mm) and micro-size ranges, which are
easier to detect and identify, leaving large knowledge gaps in our understanding of
nanoplastic debris. Our ability to ask and answer questions relating to the
transport, fate, and potential toxicity of these particles is disadvantaged by the
detection and identification limits of current technology. Furthermore, laboratory
exposures have been substantially constrained to the study of commercially
available nanoplastics; i.e., polystyrene spheres, which do not adequately
reflect the composition of environmental plastic debris. While a great deal of
plastic-focused research has been published in recent years, the pattern of the
work does not answer a number of key factors vital to calculating risk that takes
into account the smallest plastic particles; namely, sources, fate and transport,
exposure measures, toxicity and effects. These data are critical to inform
regulatory decision making and to implement adaptive management strategies
that mitigate risk to human health and the environment. This paper reviews the
current state-of-the-science on nanoplastic research, highlighting areas where
data are needed to establish robust risk assessments that take into account plastics
pollution. Where nanoplastic-specific data are not available, suggested
substitutions are indicated.
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Development and Application of Nanoparticle-Nanopolymer Composite Spheres for the Study of Environmental Processes
Plastics have long been an environmental contaminant of concern as both large-scale plastic debris and as micro- and nano-plastics with demonstrated wide-scale ubiquity. Research in the past decade has focused on the potential toxicological risks posed by microplastics, as well as their unique fate and transport brought on by their colloidal nature. These efforts have been slowed by the lack of analytical techniques with sufficient sensitivity and selectivity to adequately detect and characterize these contaminants in environmental and biological matrices. To improve analytical analyses, microplastic tracers are developed with recognizable isotopic, metallic, or fluorescent signatures capable of being identified amidst a complex background. Here we describe the synthesis, characterization, and application of a novel synthetic copolymer nanoplastic based on polystyrene (PS) and poly(2-vinylpyridine) (P2VP) intercalated with gold, platinum or palladium nanoparticles that can be capped with different polymeric shells meant to mimic the intended microplastic. In this work, particles with PS and polymethylmethacrylate (PMMA) shells are used to examine the behavior of microplastic particles in estuarine sediment and coastal waters. The micro- and nanoplastic tracers, with sizes between 300 and 500 nm in diameter, were characterized using multiple physical, chemical, and colloidal analysis techniques. The metallic signatures of the tracers allow for quantification by both bulk and single-particle inductively-coupled plasma mass spectrometry (ICP-MS and spICP-MS, respectively). As a demonstration of environmental applicability, the tracers were equilibrated with sediment collected from Bellingham Bay, WA, United States to determine the degree to which microplastics bind and sink in an estuary based of grain size and organic carbon parameters. In these experiments, between 80 and 95% of particles were found to associate with the sediment, demonstrative of estuaries being a major anticipated sink for these contaminants. These materials show considerable promise in their versatility, potential for multiplexing, and utility in studying micro- and nano-plastic transport in real-world environments.
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- Award ID(s):
- 2019208
- NSF-PAR ID:
- 10340813
- Date Published:
- Journal Name:
- Frontiers in Toxicology
- Volume:
- 3
- ISSN:
- 2673-3080
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3389/ftox.2021.752296
