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A Paraffin Microtomy Method for Improved and Efficient Production of Standardized Plastic Microfibers
Christine M Knauss1, Christopher F Dungan2, Stuart A Lehmann2
1University of Maryland Center for Environmental Science, Cambridge, Maryland, USA.
Abstract:
Microfibers are one of the most abundant microplastic particle types found in the environment, where they cause negative impacts on organisms and possibly on human health. Microfibers should be included in a wide range of laboratory studies; however, microfibers for scientific studies are not commercially available. Current methods to make microfibers generally create particles with large size ranges and poor precision, and efficient production of particles ≤100 µm is difficult. Laboratory studies of the biological and toxicological effects and chemical interactions of microfibers require uniform, small microfibers in sufficient numbers for environmentally relevant experiments. We developed a novel fiber embedding technique and modified a seminal cryomicrotomy method to produce precise microfibers in quantities suitable for environmentally relevant concentrations. Polyethylene terephthalate (PET) and nylon fibers were strategically wound onto a spindle, embedded in paraffin wax, and sectioned using a standard paraffin microtome. After processing with a suitable organic solvent to remove the wax, microfiber size distributions were assessed. The small microfibers (10-42 µm) were accurate to the target lengths with excellent precision and a production rate ≥13.5 times higher than previous methods. As a proof of application, three lengths of manufactured PET fibers were stained with Nile red and exposed to eastern oyster larvae (Crassostrea virginica) for 24 h. Larvae ingested the smaller fiber lengths (14 and 28 µm), and the Nile red-stained fibers were visible and distinguishable in the guts of the larvae. This experiment was the first to demonstrate ingestion of plastic particles other than microspheres by oyster larvae. The present method facilitates the use of small microfibers in laboratory experiments, allowing for a more complete understanding of microplastic effects in the environment. Environ Toxicol Chem 2022;41:944-953. © 2021 SETAC.
Insights
Researchers developed a new method to create small, precise microfibers for laboratory studies on microplastic pollution. This technique enables more accurate research into the environmental and health impacts of microfibers.
Area of Science:
- Environmental Science
- Toxicology
- Materials Science
Background:
- Microfibers are prevalent environmental pollutants with known negative impacts on organisms and potential risks to human health.
- Current methods for producing microfibers for research yield imprecise sizes and insufficient quantities, hindering environmentally relevant studies.
- Uniform, small microfibers (≤100 µm) are crucial for investigating biological effects, toxicological impacts, and chemical interactions of microplastics.
Purpose of the Study:
- To develop a novel and efficient method for producing small, precise microfibers suitable for laboratory research.
- To enable the creation of microfibers in quantities and sizes relevant to environmental concentrations and biological uptake studies.
- To demonstrate the utility of the manufactured microfibers in a biological experiment, specifically oyster larval ingestion.
Main Methods:
- A novel fiber embedding technique combined with a modified cryomicrotomy method was employed.
- Polyethylene terephthalate (PET) and nylon fibers were wound onto a spindle, embedded in paraffin wax, and sectioned.
- Paraffin wax was removed using an organic solvent, and the resulting microfibers were analyzed for size distribution.
Main Results:
- The developed method successfully produced precise microfibers (10-42 µm) with excellent accuracy and precision.
- Production rates were significantly increased, exceeding previous methods by at least 13.5 times.
- Nile red-stained PET microfibers were ingested by eastern oyster larvae, demonstrating the method's applicability and the biological interaction with small plastic fibers.
Conclusions:
- The novel method provides a reliable and efficient way to produce small, uniform microfibers for scientific research.
- This advancement facilitates more comprehensive laboratory studies on the environmental and toxicological effects of microplastic fibers.
- The findings open new avenues for understanding microplastic ingestion and impacts across various marine organisms.
