Environmental and Morphological Detrimental Effects of Microplastics on Marine Organisms to Human Health


 The ubiquitous presence of microplastics (MPs) in all oceans has become a significant threat to nature as global plastic production continues to increase. Now, and over the next 20 to 30 years, it is the time to address the consequences of the rise of the plastic industry global production of millions of items, ranging from a single pen to automobiles. Inappropriate management, lack of awareness of the harmful effects, reckless universal use, and indiscriminate disposal of plastics have turned the earth into a "plastic planet”. The aim of the present study review is to identify the scenarios for the structure, and functions of MPs and the resulting impacts on marine organisms. The different origins of MPs in the oceans and their negative impacts on marine organisms are critically discussed in this review. Due to their small size, these plastic particles are easily ingested by a wide range of marine organisms (e.g., fish, Mollusca, Arthropoda, Annelida, Echinodermata, Nematoda, phytoplankton, zooplankton, algae, birds, Mammalia, marine reptiles, and corals), posing a threat to their health. The ability of MPs to absorb a variety of hazardous hydrophobic chemicals from the environment allows transfers these toxins to enter directly into the food chain, ultimately becoming a threat to human health. As a result, numerous policies and laws have been created to address the major problems of marine pollution. However, these regulations need to be improved and implemented worldwide. To avert future threats, it is crucial to stop the production of toxic chemicals associated to the production of plastics and replaces them with environmentally suitable alternatives.

The water and sediments of many oceans, estuaries, and coastal lagoons are contaminated with MPs, putting marine organisms (e.g., shell sh) that grow up in these locations at risk for consumption (Lusher et al. 2017). For example, the amount of MPs particles per 10 g of mussels in commercial mussels from Belgium ranged from three to ve ( . Ingestion could occur due to the inability to identify MPs from prey or ingestion of organisms from lower trophic levels containing these particles (de Sá et al. 2015). MPs can also attach directly to organisms (Cole et al. 2013). MPs are potentially accessible to a wide range of organisms by ingestion due to their small size, which overlaps with the size range of their prey (Galloway et al. 2017). Several marine organisms are impacted by ingestion of MPs. MPs are reportedly ingested by cod, pilchard, horse mackerel, mussels, red mullet, oysters, shrimp, and sea bass (

Organisms Studied Worldwide
Fish, amphibians, birds, mammals, reptiles, crustaceans, molluscs, echinoderms, annelid worms, cnidaria, porifera, and rotifers were the focused creatures under this review research. Zooplankton was included in the "small crustaceans" category, while all other crustacean species were included in the "large crustaceans". Most of the research to date has focused on sh; more information is needed on the effects of MPs on other taxa, particularly invertebrates (

Characteristics Of Microplastics
Plastics have a variety of properties that make them usable in a wide range of applications, from construction to medicine (Bhuyan et al. 2020). Corrosion resistance, weak electrical and thermal conductivity, durability, and the ability to carry additional resources and manufacture at low cost are some of the notable features. The presence of plastics in the environment is problematic due to these characteristics. Existing information of the wide-ranging effects of large plastic fragments and their fragmentation in MPs on marine diversity is still limited (Alfaro-Núñez and Bermudez, 2018).
It should also be noted that during the manufacturing process of plastics, they are molecularly mixed with other chemical compounds that give them the special properties mentioned above and prove harmful when consumed (Fries et al. 2013). Plastics in the environment can potentially absorb other toxic chemicals (Velzeboer et al. 2014). MPs particles have a great potential to absorb environmental pollutants such as polycyclic aromatic hydrocarbons and metals due to their enormous surface area to volume ratio (Ashton et al. 2010).
Although plastic can degrade over time into smaller pieces to nanoplastics, it remains unbroken as a plastic polymer and attracts persistent organic pollutants (POPs) such as dioxins and 1,1-dichloro-2,2-bisethylene, also known as DDE, in addition to the toxic substances already present in MPs (Alfaro-Núñez and Bermudez, 2018). Polyethylene (PE) accounts for 28% of total production in Europe, followed by polypropylene (PP) with 19%, polyvinylchloride (PVC) with 10%, and polystyrene with 7% (Plastics Europe, 2020). The density of the different plastic polymers determines MP behaviour in the aquatic environment (Nizzetto et al. 2016). Furthermore, MPs occur in a variety of forms that distribute differently in different compartments of the aquatic environment due to differences in shape and density, which affects their availability to species (Cole et al. 2011).

Behaviour And Fate Of Microplastics
MPs are resistant to biodegradation at the molecular level and can persist in ecosystems for hundreds of years, posing an eminent threat to the environment and organisms. MPs enter the marine environment mainly through human activities ( MPs can be ingested by virtually all-living organisms in the ocean and are well documented in a variety of marine organisms with different feeding strategies within the food web (Table 1). MPs can affect phytoplankton, zooplankton, echinoderms, sediments, and suspended feeders (Fossi et al. 2016; Avio et al. 2015a; Cole et al. 2013). MPs can be ingested directly from the water by giant marine species, or indirectly through consumption by many other animals that may ingest or metabolize them. Numerous sh, seabirds, marine mammals and turtles have been shown to become tangled or ingest plastic items such as ropes, shing nets, plastic bags, etc., which can lead to ulcers or starvation and ultimately death of the animal (Alfaro-Núñez and Bermudez, 2018). MPs can be stored in the organism or transported through body tissues, or they can be excreted or ingested via pseudo-faeces (Avio et al. 2015a; Van Cauwenberghe and Janssen, 2014). MPs that accumulate in the ecosystem can have a variety of negative effects on the organisms that ingest them. Internal or external trauma, digestive system blockages leading to pseudo saturation, and physiological stress, alteration of nutrition and growth retardation, loss of infertility, fecundity, and progeny survival are   Polyester is a polyethylene terephthalate fabric that is widely used for its strength, physical properties, and distinct wear properties (Carr, 2017). Polyester, which accounts for about half of the world's bre industry, is mainly used for apparel fabrics and other processed textile goods (Carr, 2017). 35% of bres from MPs are generated from washing synthetic textiles and 28% from tyre erosion particles (Boucher and MPs include granules from pre-production and elements in a variety of items, including fragments of shing gear, packaging and beverage cans, synthetic textiles, vehicle tyres, coatings, skin care, and beauty products, and electronic devices (Andrady, 2011;GESAMP, 2016).
Sources and transport of MPs in the ocean are shown in Fig. 3.
Another more recent vast source of MPs, which ultimately ends up wasted into the oceans, comes from the massive global production of disposal masks, face screens, plastic laboratory, medical materials, and antigen rapid test kits (home self-testing) that has substantially increased during the current COVID-19 pandemic (Alfaro-Núñez et al. 2021).

Aggregations
The hydrophobic properties of MPs allow them to collect and incorporated into marine aggregates such as marine snow. Depending on the type of plastic, there is an increase in total particle size, which can affect density. As a result, they become bioavailable to species of different sizes and in different layers of the water column. Externally, MPs has been observed to accumulate on the copepod antennae, limbs, swimming appendages, feeding apparatus, and furca (Cole et al. 2013). This led to blockages that would further limit motility, feeding, reproduction and mechanoreception. The formation of these accumulations has also been observed in the digestive system

Substrate For Pathogens
Pathogenic microorganisms that cause infections can be detected on the surface of MPs and bene t from the aggression that these particles generate. For example, MPs have been found to contain Vibrio sp. in the environment, a bacterial species associated with foodborne illness (

Materials And Methods For The Data Collection And Analyses
Online study sites Data have been collected from many countries around the world. Results from the publications of various scientists and researchers are presented.

Data collection
The rst phase involved the identi cation of related studies. In order to conduct a systematic literature search, the following speci cations were created for the database: The data were tagged with the keywords "Impacts of microplastics on marine organisms" "Effects of microplastics on marine organisms" "Toxicity of microplastics on marine organisms" or "Adverse impacts of microplastics on marine organisms" or "Biomagni cation of microplastics on marine organisms" or "Impacts of microplastics on marine sh" or "Impacts of microplastics on marine invertebrates" or "Impacts of microplastics on marine birds" or "Impacts of microplastics on marine turtles" or "Impacts of microplastics on marine molluscs" or "Impacts of microplastics on marine Arthropoda" or "Impacts of microplastics on marine Annelida" or "Impacts of microplastics on marine Echinodermata", etc. A search for "Impacts of microplastics on marine organisms" in the Dimension database revealed numerous research papers (Fig. 4).

Results Of The Bibliometric Analysis
The dataset of article information was recorded in the Dimension database as a CSV le. Then, the CSV le was used in the VOS viewer software (version 1.6.17) for the bibliometric analysis. The type of analysis and the unit of analysis were set up as co-authorship and authors, respectively. The full count method was implemented for this analysis. The threshold for the minimum number of publications for authors was and the number of citations was set to 1. Association was used as the normalization method. Then, the program was run providing the following results. A total of 64 clusters were recorded, where cluster 1 contained 18 items, cluster 2 contained 15 items, cluster 3 included 13 items, cluster 4 included 11 items, cluster 5 comprised10 items, cluster 6 covered 9 items, cluster 7 included 8 items, cluster 8 contained 8 items, cluster 9 covered 7 items and cluster 10 included 7 items (Fig. 5). "lyons, daniel m" showed the highest total link strength (19) followed by "oral, rahime", "pagano, giovanni", "thomas, philippe j", "toscanesi, maria" and "trifuoggi, marco". "rochman, chelsea m" have a total connection strength of 18 and are closely connected.

Impacts of microplastics on marine organisms
Most natural nano-plastics and MPs are less than 100 nm in size and are found in seawater. In general, these microscopic particles have a detectable impact on marine species (Table 2). MPs, on the other hand, cannot molecularly be degraded or assimilated after consumption because marine organisms do not have the necessary enzyme pathways to degrade the synthetic polymers, and can therefore be classi ed as bioinert substances (Andrady, 2011). It has long been known that ingestion of MP can cause a number of health problems. MPs are known to harm aquatic organisms in a variety of ways, including effects on growth and development, reduced food intake, gut blockage, changes in swimming behaviour, and impaired reproductive success (   Impacts on gastropods-molluscs Non-lter-feeding, larger organism like gastropods feed on certain amounts of MPs bre to ensure retention through ingestion and impact analysis (Ehlers et al. 2020;Jabeen et al. 2018). Radix balthica has been recorded to eat a bio lm of MPs bres during feeding. Subsequently, MPs bres were gradually absorbed into a bre-free medium via faeces, which took three days (Ehlers et al. 2020). Planorbella campanulata was exposed to exceptionally high levels of polyester textiles in the marine environment, and the bres accumulated in the snail's mouth, resulting in a higher mortality rate than in control snails (Philips et al. 2020). As a result, degradation at local hot spots with high bre concentrations can lead to blockage of feeding and death of snails. In addition, snails produced more offspring when treated with polyester bres. This is thought to be because death triggers an increase in offspring or because the chemicals evaporated from the bres have estrogenic effects (Philips et al. 2020). Ingestion of polystyrene microbeads by veliger of the marine gastropod Crepidula onyx resulted in a slowed development rate as well as premature settling on the sea oor (Lo and Chan, 2018), which may negatively impact post-settlement e cacy. Moreover, those individuals subjected to the microbeads only during the larval stage grew more slowly 65 days after MPs removal. This highlights the potential for adverse long-term effects of early-life exposure on development. In contrast, the adult stage was unaffected at environmentally relevant MP concentrations.

Impacts on Arthropoda
Filter and deposit-feeding decapods passively ingest MP bres, while selectively feeding decapods aggressively feed on them. Oryzias lapites, a Japanese medaka sh was found to contain chemical contaminants (PAHs, PCBs and PBDEs) that accumulate in the body, as evidenced by bioaccumulation. Liver stress and early tumour formation were reported after animals were exposed to both pieces of primary and marine plastic pieces for a short time (

Impacts on Annelida
Annelids are marine worms that irrigate and provide oxygen and promote the growth of crops and algae. The ecological role of marine worms in oceanic reefs is to provide food for aquatic species higher up the food chain (von Palubitzki and Purschke, 2020). Species inhabiting sediments can be affected by MPs, which, depending on the degree and concentration of exposure, can lead to serious changes such as alteration of gut microbiota, suppression of growth, and reproduction of collembolan in the soil (Zhu et al. 2018). In response to high doses of HDPE, PLA, and PVC in sandy sediments, respiration rates of Arenicola marina increase (Green et al. 2016). Decreases in energy reserves have also been noted, which may be due to in ammatory responses in tissues, as well as decreased food intake to decolonize or deposit of MPs in digestive cavities (Wright et al. 2013). As a result, stress may affect the health and behaviour of the polychaete A. marina, such as feeding performance and sediment transformation, negatively impacting ecological processes (Green et al. 2016). In addition, A. marina accumulated nonylphenol and triclosan from PVC when exposed to high levels of plastics, resulting in immune system impairment physical stress, and death (Browne et al. 2013). Exposure to PS MPs has ecotoxicological effects on the polychaete A. marina, including reduced feeding activity and lysosomal membrane stability (Besseling et al. 2013). When A. marina was exposed to PS MPs, it was noted an increase in energy consumption (Wright et al. 2013). Lipid stores of A. marina exposed to sediment PVC were emptied, and an in ammatory response was observed.

Impacts on Echinodermata
Echinoderms MPs affected oceanic planktotrophic pluteus larvae of the sea urchin P. lividus (Messinetti et al. 2018). When sea urchins, Lytechinus variegatus, were exposed to seepage generated from unused polyethylene beads, abnormal embryonic development increased by 66.

Impacts on phytoplankton
Phytoplankton is the mainstay of the entire marine food chain and provides the primary food source for much of the ocean's biodiversity.
The impact of MPs on microalgae is also becoming an increasingly important issue of global concern (Cunha et al. 2020; Ansari et al. 2021). Microalgae are an important source of energy for most marine ecosystems, feeding a wide range of organisms from tiny zooplankton to molluscs and crustaceans (Glibert, 2019). These species are the next in the food web to be preyed upon. Phytoplankton are credited with generating half of the Earth's photosynthetic activity and thus much of the new biomass that is converted to chemical energy by the sun's energy and underpins trophic webs. Because of their important, there is concern about the adverse effects of micro and nanoplastics on them (Koenigstein, 2020).
It is known that algae cells of the genera Chlorella and Scenedesmus can aggregate and absorb nanoplastic beads (0.02 m) due to their shape and motility, leading to a reduction in photosynthesis and the development of oxidative damage (Bhattacharya et al. 2010).
The physicochemical properties of MP's and the physical and metabolic properties of algae appear to be responsible for this adsorption; in particular, a strong attraction between algae and positively charged plastic particles has been described (Bhattacharya et al. 2010). Sjollema et al. (2015) found no suppression of photosynthesis in the marine agellate Dunaliella tertiolecta when exposed to different types of plastic particles of different sizes. Uncharged polystyrene beads inhibited microalgae development by 45%, but only at very high levels (250 mg/L). The negative effect increased with decreasing particle size (Sjollema et al. 2015).

Impacts on zooplankton
Zooplankton is considered a vital diet source for various secondary marine organisms. It serves as a pathway for MPs to enter the food web and reach the higher trophic levels (Botterell et al. 2019). Zooplankton can exhibit different feeding behaviours depending on species, life stage, and prey accessibility (Cole et al. 2013). Prey selection is in uenced by the size of the hunter relative to the prey, their swimming behaviour, and the susceptibility of each prey type to the predator once encountered. A combination of mechano-and chemoreceptors also aid in the selection of suitable prey (Cole et al. 2013). MPs are likely ingested through unselective feeding techniques, such as suspension feeding, where prey are often not selectively eaten (Cole et al. 2013). Some zooplankton species may alter their feeding habits to prefer one algal species to another, and plastic pellets can be mistaken as a prey. In addition, when exposed to MPs and algal prey, the copepod Calanus helgolandicus preferred algal prey of smaller size . This change in feeding behaviour suggests that copepods alter their feeding habits to avoid ingesting MPs. MPs have not been found in all zooplankton species. Cole et al. (2013) reported ingestion of MPs in Parasagitta sp. and Siphonophorae sp. across a size range. However, both species are raptors, and active foragers require an animal prey response, which may explain why immobile MP prey did not tempt them (Table 3). -Fecal pellets packed with MPs are consumed by copepods.
-Algal feeding is considerably reduced when exposed to 7.3 µm MPs (> 4000 beads/mL). -MPs had no effect on copepods' fecal pellets growth rate.
-Copepods that were exposed to MPs experienced stress-induced reproduction. MPs/mL -Copepods exposed to MP bres have a larger effect on their eating than copepods exposed to pieces.

Rodriguez-
-Feces having small polyethylene sink at a slower pace than controls, but when high-density MPs are mixed into the fecal pellets, the sinking rates dramatically increase. -Long-term exposure to polystyrene beads reduces reproductive output considerably, but has no effect on egg formation rates, breathing, or longevity.

Paracyclopina nana
Polystyrene microbeads 0.05, 0.5, 6 10 ng/mL -The 0.05 µm pellets can be found everywhere over P. nana's body, whilst the other two sizes are predominantly found in the digestive systems.
-When compared to the other two sizes (0.5 and 6 µm), the 0.05 µm nanobeads have a longer retention duration in the body.
-In copepods, MPs lead to oxidative stress. particles/mL -Egg production is lowered in a dose-dependent approach after 5-days of exposure to MPs.
-In contrast to the control, exposure to MPs (2 x10 4 plastics/mL) for 6-d reduces population size by 75%, whereas populations exposed for a longer period of time (24-d) exhibit more severe depletion (i.e., 60 percent of control). -In the marine ecosystem, MPs can be transported from copepods to jelly sh ephyryae.
-When compared to the control, exposure to 0.5and 6-µm polystyrene microbeads dramatically reduces fecundity at concentrations (1.25-25 mg/L), however 0.05-µm PS nanobeads have no effect on this feature. -MPs had no effect on the body size of T. japonicus after one generation. Copepods in contact to nylon pieces or bres reduced their food ingestion in treatments with suspended bres, but not in the fragment's treatments ). Reduced food ingestion and the resulting decrease in existing energy will have a long-term impact on tness (Watts et al. 2015). When the maritime copepods C. helgolandicus and T. japonicas were exposed to PS MPs, it was found a reduction in survival and productiveness (Cole et

Impacts on algae
Algae capture and utilise energy from sunlight, and biochemically transform carbon dioxide (CO 2 ) and water (H 2 O) to make organic matter.
They are regarded as an essential component to the health of the world's oceans (Singh and Singh, 2014). This cycle contributes to the ocean's life balance. Algae can also be used as a source of food and medicine for people. MPs caused morphological alterations, lower growth, and photosynthetic activity is lowered (Table 4)   There was a 39.7% growth reduction in 1 µm particle exposure, but no in uence on algal growth. There is a lot of absorption and aggregation. . High concentrations of phthalates and OCs have been shown to impair antioxidant defences and other systems that prevent cellular damage in B. physalus, leading to oxidative stress and possible hormonal system abnormalities (Fossi et al. 2016). In addition, microscopic plastic particles have the potential to clog the ltration systems of organisms (Simmonds, 2012). The fate of MPs in the body of mammals is shown in Fig. 6.  Table 5. Impacts on coral The rst study on the consequences of MPs consumption in corals was published in 2015 by Hall et al. (2015). Blue MPs can be ingested by Dipsastrea pallida at feeding rates of 1.2-55 g plastic cm -2 h -1 . Ingestion and exposure of MPs have negative effects on the symbiosis between corals and zooxanthellae (Huang et al. 2020). MP aging characteristics contribute to plastic ingestion by a variety of corals and have additional negative consequences. Table 6 summarizes what is known about the various effects of MPs on coral species.  Wright and Kelly, 2017). Consequently, MPs act as a conduit for toxic contaminants from marine organisms into the human body (Fig. 7), and pose a major threat to human well-being

Management Strategies To Control Mps In The Marine Environment
The following management strategies may be feasible and practical to control the loss of microplastics to the ecosystem during manufacture, use, and discarding (Prata et al. 2019): Control the production and consumption of environmentally harmful plastic items through bans or levies without compromising public health or food security.
Reducing plastic consumption without unforeseen consequences by eliminating unnecessary packaging, labeling, raising awareness and education, and offering environmentally friendly alternatives to plastics where appropriate.
Growing demand for recyclable materials through incentives, penalties, or taxes on recycled plastic.
Adopt waste collection methods that reduce waste production and improve recyclability, such as door-to-door pickup and depositrefund procedures, based on a "pay-as-you-throw" philosophy.
Reduce and recycle waste generated during operations and provide accountability for waste and product impacts Reduce environmental impact of recycled plastics, use renewable energy in waste and recycling processing.
Develop a life cycle analysis (LCA) for each product and process to improve eco-design, taking into account the expected end of life of the product.
To optimize e-waste recyclability and, in the meantime, energy recovery To lessen the impact of plastics and MPs on the ecosystem, the different countries and organizations need to develop effective rules and laws.

Knowledge Gaps/ Future Research Recommendations
The opinions on what are "knowledge gaps" varies a lot, probably based on the eld of interest of the researchers stating the gaps. In general, the consensus is that there are substantial knowledge gaps related to: More laboratory studies should be conducted on the most common forms ( bres and pieces) and sizes (800-1600 µm) of MPs detected in eld samples of living material.
Experimental studies on microplastics in soils and agriculture are very few compared to other elds in which microplastics have been studied.
MPs content is likely to increase in the future, and it will become increasingly important to regularly monitor MP content in marine organisms and other foods.
The amount of MPs in edible sh and shell sh tissue needs to be determined. Quanti cation of palatable echinoderms, tunicates and algae consumed in many countries should also be investigated.
Continuous monitoring programmes are needed to assess the occurrence of MPs in ecological sections and to prevent depletion of global sh and shell sh stocks.
Studies should focus on the chemical and microbial hazards and risks associated with MPs ingestion and on improving methods for assessing MPs ingestion and translocation to humans.
It is critical to investigate the hazards and risks to consumers from MPs -contaminated sh, shell sh, and food using food safety risk assessment methods.
The inclusion of a wide range of MPs -sizes and components in somatic cells and the development of new methods to detect the presence of MPs in the human body are urgently needed.
Another urgent issue is the presence of nano-sized plastics in seafood, which has received less attention.
Universal standardisation of methods and procedures to allow comparison of results between different sites, organisms and environments.
Further studies on analytical techniques, toxic-kinetics and toxicology to improve our understanding of the potential impact of micro and nanoplastics on seafood quality and human health.
Understanding the methods by which PE affects organisms other than sh and the effects of PS on organisms other than sh and tiny crustaceans.
Investigate MPs ecotoxicity under more realistic conditions, such as mesocosms and multispecies exposures.
Getting people to disclose unfavourable negative results.

Declarations
Declaration of competing interest The authors claim that they have no known competing nancial or personal interests that could have impacted the ndings of this study.      Co-authorship among authors who had a joint publication related to the effects of MP on marine organisms.  MPs ingestion routes in human body and possible effects.