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Review
. 2023 Jan 18;20(3):1745.
doi: 10.3390/ijerph20031745.

Microplastic Pollution: Chemical Characterization and Impact on Wildlife

Sumon Sarkar  1 , Hanin Diab  1 , Jonathan Thompson  1
Affiliations
Review

Microplastic Pollution: Chemical Characterization and Impact on Wildlife

Sumon Sarkar et al. Int J Environ Res Public Health. .

Abstract

Microplastics are small pieces of plastic that are less than 5 mm in size and can be found in most environments, including the oceans, rivers, and air. These small plastic particles can have negative impacts on wildlife and the environment. In this review of the literature, we analyze the presence of microplastics in various species of wildlife, including fish, birds, and mammals. We describe a variety of analytical techniques, such as microscopy and spectrometry, which identify and quantify the microplastics in the samples. In addition, techniques of sample preparation are discussed. Summary results show that microplastics are present in all the wildlife species studied, with the highest concentrations often found in fish and birds. The literature suggests that microplastics are widely distributed in the environment and have the potential to affect a wide range of species. Further research is required to fully understand the impacts of microplastics on wildlife and the environment.

Keywords: fibers; microplastics; one health.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 6
Figure 6
(A) Schematic of the fundamental principles of Raman spectroscopy, highlighting the main scattering and fluorescence excitations of a sample after it is excited using a monochromatic light source of frequency equal to ν0. The Raman stokes line experiences a frequency shift of Dν that corresponds to the difference between vibrational energy levels. (B) A benchtop, commercially available Raman microscope. (A) from Ref. [67] via Creative Commons license and (B) from Thermo Fisher Scientific.
Figure 1
Figure 1
Top—General workflow for microplastics analysis. Samples are initially digested to dissolve and remove inorganic and organic materials before gravimetric or filtration-based separation. Finally, chemical analysis of microplastics can be achieved. Bottom—Overview of microplastics and nanoplastics separation and analysis methods in simple and complex matrices. Figure reproduced from [35] with permission of the publisher.
Figure 2
Figure 2
(A) Optical microscope images of microplastic particles: (a) Polyethylene (PE) particle; (b) polyethylene terephthalate (PET) particle; (c) polypropylene (PP) particle; (d) polyvinyl chloride (PVC) particle. (B) Microplastics of six different polymer types, dyed with Nile Red (1000 μg·mL−1 for 30 min). Figures reproduced from Abbasi et al. [38] and Maes et al. [46] with permission of publishers.
Figure 3
Figure 3
(A) Schematic of an SEM instrument [54]. (B) SEM images (a1–d1) and EDX spectra (a2–d2) from suspect microplastic particles isolated from marine organisms. SEM with EDX allows investigators the ability to exclude particles from being microplastics, as is case of object (d1), which appears to be silica [51]. (C) SEM images from microplastic (A–D); SEM images of microplastic debris extracted from the stomach contents of Bursatella leachii specimens [55]. Figures have been reproduced with permission of publishers.
Figure 4
Figure 4
Left—Schematic of an FTIR microscope. Reprinted with permission from the March/April 2014 edition of BioOptics World Copyright 2014 by PennWell. Right—Photograph of a modern FTIR benchtop microscope. Photograph provided by Thermo Fisher Scientific.
Figure 5
Figure 5
(A,B)—FTIR spectra and optical images of MPs of various compositions. Characteristic peaks differ based upon MP composition. Figures have been reproduced from Refs. [40,58] with permission of publishers.
Figure 7
Figure 7
Raman spectra of a variety of synthetic polymers common to microplastics. Figure reproduced from Ref. [68] with permission of publisher.
Figure 8
Figure 8
Direct comparisons between Raman and FTIR spectra/imaging of microplastics. (a) A Raman image (left) and an IR image (right) with false coloring denoting the spectral intensity in the 2780–2980 cm−1 range. (b) A Raman spectrum (left) and an IR transmission spectrum (right) of particle 2 in comparison with a reference of polypropylene. (c) Images of unknown particles extracted from sediment and scanned via both FTIR and Raman microspectroscopy. (a,b) reproduced from Ref. [70] with permission from Springer Nature; (c) reproduced from Ref. [48] with permission of publisher.
Figure 9
Figure 9
CAT activity (a), SOD activity (b), and ROS content (c) in zebrafish intestines after 14- and 21-day exposures to BSA, PS, or PS + BSA. * p < 0.05 and ** p < 0.01 indicate significant differences between the treatment groups and the control group. # p < 0.05 indicates significant differences between the two groups indicated. Figure reproduced from Luo et al. [74] with permission.
Figure 10
Figure 10
Effects of PS-MPs exposure on myocardial development. (A) Histopathological damage to the myocardium at different concentrations of PS-MPs (objective magnification of 10× and 20×). (B) Relative mRNA expression level of TnnT2, Nkx2-5, Gata4, TBX5 and ACTN2. (C) Heat maps of relative mRNA expression. (D) Protein level of Gata4 and ACTN2. The results are presented as mean ± standard deviation (SD), compared to the control group, *** p < 0.001. Figure reproduced from Ref. [82] with permission of publisher.
Figure 11
Figure 11
The mass of proventriculus microplastics (>1 mm) correlates with organ microplastics (<1 mm) and organ pathology. Inserts (a,e,i): The correlation between the mass of proventriculus microplastics (grams) with tissue microplastics identified through histology in the proventriculus (a), kidney (e), and spleen (i). Inserts (b,f,j): The correlation between the mass of proventriculus microplastics with mean tissue pathology score (0–5) in the proventriculus (b), kidney (f) and spleen (j). Inserts (c,g,k): The correlation between the tissue microplastics with mean tissue pathology score (0–5) in the proventriculus (c), kidney (g), and spleen (k).Inserts (d,h,l): Histological examples of healthy tissue (i) and tissue pathology (ii) in the proventriculus ((d), inflammation and hemorrhage; scalebar 100 μm), kidney ((h), collapsed glomerus around microplastic (arrow), scalebar (μm), and spleen. Figure reproduced from Ref. [84] under the Creative Commons Attribution License.
Figure 12
Figure 12
Spectrum of current knowledge regarding microplastics.
See this image and copyright information in PMC

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