86
T. A. Aragaw and B. A. Mekonnen
individuals, then the population, and finally disturbing the community structure and
function as a whole. Consequently, MP pollution in the water ecosystem poses a risk
to biota across the range of cells to the population level of biological organization [12].
5.1 Toxicity Effect at Subcellular, Cellular, and Organ Level
of Biota
Several studies have intensively reported the individual-level effects of MP ingestion
in adult organisms at the cellular and subcellular levels. For example, the ingestion
and tissue accumulation of polystyrene MP (PS-MP), and its toxicity were detected in
liver organs of [60]. The experimental investigation of PS-MP exposure for seven days
showed the accumulation of 5 μm PS in the gill, liver, and gut, whereas 20 μm MP
was found in fish gill and gut only. Further, the histopathological analysis indicated
that the smallest sizes of 5 μm and 70 nm PS-MP caused redness and lipid buildup
in the fish liver. Moreover, PS-MP also considerably increased superoxide dismutase
(SOD) and catalase (CAT) activities in fish liver. In addition, exposure prompted
modifications of metabolic profiles in fish liver and distressed the lipid and energy
metabolism [60]. Similarly, impacts of ingested PS-MPs (5-μm beads, 50 μg/L, and
500 μg/L) on zebrafish were examined in the gut after 21 days of the exposure period.
The result showed a noticeable adverse impact of PS-MPs ingestion by zebrafish on
the adult growth rate, fecundity. The internal exposure of MPs to the circulatory
system, tissue, and organs affect metabolic disorders and sublethal responses in
organisms. Consequently, the effects result in endocrine disorders, oxidative stress,
immune responses, and gene expression alteration [61]. Furthermore, the metabolism
and growth of an adult male zebrafish were critically affected by PS-MPs. As shown
in Table 2, the ingestion of the PS-MP (0.5 and 50 μm) in the guts of the adult
zebrafish enlarged the volume of mucus and triggered inflammation after 14 days
of ingestion. The high-throughput sequencing of the 16S rRNA gene V3–V4 region
and the operational taxonomic unit analysis discovered an in-depth response at the
phylum and genus levels, suggesting that the MP exposure within the gut changed the
richness and variety of the microbiota, leading to a microbial imbalance [62]. Further
to chronic exposure of MPs, Watts et al. [63] examined that acute aqueous exposure
to PS-MP (8 μm) ingestion and inhalation by the shore crab Carcinus maenas. The
result has shown that exposure to PS-MP has a little degree of effects on the oxygen
consumption of the shore crab Carcinus maenas. However, a significant reduction in
the hemolymph sodium ions and a rise in the calcium ions were observed in cellular
metabolism [63].
In other studies, Jeong et al. [64] assessed accumulation and antagonistic impacts
of ingestion of 0.05-, 0.5-, and 6-μm polystyrene in microbeads monogonont rotifer
(Brachionus koreanus). The analysis of the introduction of all sizes of polystyrene
microbeads caused impacts on the growth rate, fertility, life expectancy, and reproduction time. The rotifers exposed to the smallest particles (0.05-μm) were effectively
T. A. Aragaw and B. A. Mekonnen
individuals, then the population, and finally disturbing the community structure and
function as a whole. Consequently, MP pollution in the water ecosystem poses a risk
to biota across the range of cells to the population level of biological organization [12].
5.1 Toxicity Effect at Subcellular, Cellular, and Organ Level
of Biota
Several studies have intensively reported the individual-level effects of MP ingestion
in adult organisms at the cellular and subcellular levels. For example, the ingestion
and tissue accumulation of polystyrene MP (PS-MP), and its toxicity were detected in
liver organs of [60]. The experimental investigation of PS-MP exposure for seven days
showed the accumulation of 5 μm PS in the gill, liver, and gut, whereas 20 μm MP
was found in fish gill and gut only. Further, the histopathological analysis indicated
that the smallest sizes of 5 μm and 70 nm PS-MP caused redness and lipid buildup
in the fish liver. Moreover, PS-MP also considerably increased superoxide dismutase
(SOD) and catalase (CAT) activities in fish liver. In addition, exposure prompted
modifications of metabolic profiles in fish liver and distressed the lipid and energy
metabolism [60]. Similarly, impacts of ingested PS-MPs (5-μm beads, 50 μg/L, and
500 μg/L) on zebrafish were examined in the gut after 21 days of the exposure period.
The result showed a noticeable adverse impact of PS-MPs ingestion by zebrafish on
the adult growth rate, fecundity. The internal exposure of MPs to the circulatory
system, tissue, and organs affect metabolic disorders and sublethal responses in
organisms. Consequently, the effects result in endocrine disorders, oxidative stress,
immune responses, and gene expression alteration [61]. Furthermore, the metabolism
and growth of an adult male zebrafish were critically affected by PS-MPs. As shown
in Table 2, the ingestion of the PS-MP (0.5 and 50 μm) in the guts of the adult
zebrafish enlarged the volume of mucus and triggered inflammation after 14 days
of ingestion. The high-throughput sequencing of the 16S rRNA gene V3–V4 region
and the operational taxonomic unit analysis discovered an in-depth response at the
phylum and genus levels, suggesting that the MP exposure within the gut changed the
richness and variety of the microbiota, leading to a microbial imbalance [62]. Further
to chronic exposure of MPs, Watts et al. [63] examined that acute aqueous exposure
to PS-MP (8 μm) ingestion and inhalation by the shore crab Carcinus maenas. The
result has shown that exposure to PS-MP has a little degree of effects on the oxygen
consumption of the shore crab Carcinus maenas. However, a significant reduction in
the hemolymph sodium ions and a rise in the calcium ions were observed in cellular
metabolism [63].
In other studies, Jeong et al. [64] assessed accumulation and antagonistic impacts
of ingestion of 0.05-, 0.5-, and 6-μm polystyrene in microbeads monogonont rotifer
(Brachionus koreanus). The analysis of the introduction of all sizes of polystyrene
microbeads caused impacts on the growth rate, fertility, life expectancy, and reproduction time. The rotifers exposed to the smallest particles (0.05-μm) were effectively