On the Creating of Health Risk: Microplastics
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Sajith Karunarathne, Thilakshani Atugoda, Meththika Vithanage
Ecosphere Resilience Research Center, Faculty of Applied Sciences, University of Sri Jayewardenepura
Today, lightweight and buoyancy assisted plastics debris are scattered in many parts oceans and float, exposing them to physical, chemical, and photolytic degradation for many centuries.
Microplastics are considered to be microscopic particles, including plastic fragments, fibers, or granules associated with polymer materials. Although microplastic is defined in numerous size ranges; generally, it attributes to plastic particles in size range of 100 nm to <5 mm diameter. Microplastics can be identified in two categories, such as primary and secondary.
Primary microplastics are those specifically manufactured in the micrometre size range for different applications in industrial use or in personal care products etc. Secondary microplastics are formed as a result of meso and macroplastic litter fragmentation.
As a result of the exposure to UV radiation, high temperatures, and wave action (in marine environment), most plastics can undergo chemical or physical changes making plastics brittle and thus more susceptible to fragmentation contributing to the formation of microplastics.
All plastics consist of synthetic or semi-synthetic polymers that can be again molded into small particles. Plastics are typically made from organic compounds such as petrochemicals, and these plastics made from long-chain polymers. These majorities of polymers consist of pure carbon chains or with oxygen, nitrogen and sulfur attached to them. To customize the properties of plastics, different molecule groups will hang on the chain backbone. Generally plastics have key properties such as high molecular mass, transparency etc. Plastics can be of few different types, such as Polyethylene Terephthalate (PET or PETE or Polyester), High-Density Polyethylene (HDPE), Polyvinyl Chloride (PVC), Low-Density Polyethylene (LDPE), Polypropylene (PP) and Polystyrene (PS) used in different applications.
The usage of a variety of plastics is varied according to their physical and chemical properties. For example, PET plastic, also known as wrinkled free plastics, are mostly used for food and drink packaging purposes. It is widely used for packaging because it is harder than polythene and also it has the ability to prevent oxygen movement preventing the spoiling of food or drinks inside. It also prevents carbon dioxide in carbonated beverages being released out. Basically PET plastics partials are ubiquitous microplastics found in the sea.
PET plastics are being used ina vast range of products due to its durability and user-friendliness. HDPE is denser and stable than PET because it has a virtually unbranched chemical chains. Due to it higher density and stability, HDPE is commonly used as the grocery bag, opaque milk, juice container, shampoo bottles, and medicine bottle. Even though plastics are considered as a user-friendly and secure packaging option, some studies show that it can leach estrogen-mimicking additives when exposed to UV light. However, PET is considered as the most hazardous plastic because it can release bisphenol A (BPA), phthalates, lead, dioxins, mercury, and cadmium which are carcinogenic.
Likewise, other plastics also cause numerous diseases and disorders.PVC is known as the second widely used plastic variety after PET and commonly used for toys, blister wrap, cling wrap, detergent bottles, loose-leaf binders, blood bags and medical tubing. Some plastics release toxic gases such as methane, carbon dioxide into their environment during their degradation.
Though there are many advantages of different types of plastics, it is evident that most plastics contain carcinogenic substances. These carcinogenic substances can be released into air or water directly or indirectly, depending on the environmental conditions in which these plastics are found.Microplastics have directly used commercially in many products, such as toothpaste, pallets, cosmetics, detergents and etc. Primary microplastics are introduced into the environment through these commercial activities as direct runoff of industrial or through usage as domestic wastewater discharges, contributing directly to environmental pollution. Synthetic microfibres have been identified as the most abundant microplastic particle type found throughout freshwater, terrestrial, and marine environments. Secondary microplastics derived from plastic litter are introduced to the environment mostly through intentional or unintentional releases such as unmanaged municipal, industrial solid waste or individuals creating litter.Urbanization has been observed as one of the most significant factors influencing presence of secondary microplastics in marine environments, with plastics being introduced from a variety of sources including effluent, road runoff, haphazard waste disposal, and atmospheric deposition.
Today, there is much research carried out to identify and quantify microplastics in the environment. Once in the environment, microplastics can quickly enter into the digestive tract of aquatic organisms and then transmitted to other organisms through the food chain. Microplastics are very easy to accumulate in aquatic living organisms because of their size specially particles less than 300 micrometer. Hence, microplastics can easily ingest into marine species specially fishes and other sea animals. Most researchers reported that microplastic fibers are abundantly found in the digestive tract in fishes because most fish nets are made from plastic fibers.
Microplastics also acts as vectors for several substances such as heavy metals and antibiotics.
There are many types of research carried out to investigate the adsorption of heavy metals to microplastics, their flow and transport. Studies have found thatvirgin PVC and Ps (Polystryne) fragments in seawater adsorbs Zn and Cu, leaching from autofouling paint. These heavy metal adsorption to PVC and Ps results in significant implications on the environment and marine life. The microplastic-metal complexes also can then enter human via consumption.
There are some organic compounds that canbe transported attached to microplastics. For example, organic compounds such as antibiotics, persistent organic pollutants (PoP’s),PAHs (Polycyclic aromatic hydrocarbons) and PCBs (Polychlorinated biphenyls) can adsorb microplastic particles via various interactions.PoP’sare producedusing various biosynthetic pathways artificially while sometimes these are also produced naturally through the explosion of volcanos as well. In old days it was used as solvents for different chemicals. They are specially made with halogenic compounds and as a result, become more soluble in lipids. They tend to accumulate in human body, especially in fatty tissues.
Apart from that, they show their negative impacts on the environment through long-range transport, which allows them tore-concentrate in different sources in high levels.Generally, PoPs can be divided into two subsets such as PBTs (Persistent, Bioaccumulative and Toxic) or TOMPs (Toxic Organic Micro Pollutants) based on how it accumulates in the biological bodies.
To make things worse, PoPs resist chemical and photolytic degradation as well. Today, antibiotics and antibiotic-resistant bacterial development is a huge global threat.Antibiotics are one of the major organic compounds responsible foradverse negative effects by bonding with microplastics and results in the development of MDR (multi drug resistant bacteria)superbugs. There are different classes of antibiotics based on their reactive ability to different pathogens.It is well known that excessive amounts of antibiotics will be harmful to our health as well as to our normal gut microflora. There are several beneficial bacteria that live in our gastrointestinal tract. Overuse of antibiotics, can be harmful to our normal gut microflora.
For an example,clostridium difficiale is a severe disease related to gut microfloraresulting in severe pains and diarrhea conditions. There are enough evidenceto say that antibiotics affect adversely for humans as well as terrestrialand aquatic organisms. As antibiotics are chemical organic compounds, degradation of them directly impact the environment especially leading to marine pollution.
It is evident that combination of antibiotics with microplastics will be exert their impact on marine ecosystems. Once these enter the food web even at a remote link, it canadversely affect every individuals even though the induvial does not take an antibiotic. There are some studies revealed that there is high affinity of antibiotics such as amoxicillin, tetracyclin and ciprofloxacin over five different antibiotics to MP. Other than that there are less studies have been carried out about sorption of antibiotics to MP.
PAH’s (Polycyclic aromatic hydrocarbons) are carbon aromatic compounds that can adsorb and make complications with different kinds of microplastics. PAH’s are produced naturally through volcanic activities well as synthetically. Naphthalene is one of the simple double ring aromatic PAH compound while anthracene and phenanthrene have three rings. These aromatic rings can easily get bonded with microplastics through different chemical and physical reactions. Because of these formations and complications on PAH’s and its aromatic rings, they adversely affect human health resulting in mostly respiratory disorders.
In contrast to other organic compounds, PAH’s are found in majority of carbonic compounds in very significant amounts. PCB (Polychlorinated biphenyls) is a type of organic contaminant that also have ability to migrate long distances by binding with microplastics. PCB can be found in everywhere and accumulate into environment through accidental leaks, spills, electricals and other equipmentand improper disposal and storage.Due to its nature, PCB’s can be found in air, land as well as in marine environments. When PCB’s release into whatever the environment, it shows adverse effects by binding to microplastics and migrates long distance like other organic compounds. Further, additives that are added into plastics when they are manufactured for different purposes are persistent organic compounds (POPs) can also flow and transport with microplastics to contaminate virgin natural environments.
As mentioned earlier microplastics are very diverse in all environments because there are various categories of microplastics such as high density polyethylene (HDPE), low density polyethylene (LDPE) and PP (Polypropylene), PET and PVC. Among those, PET and PVC have a higher potential to accumulate in greater concentrations compared to others. All microplastics are hydrophobic and some are organic.
Hence, these can get transported through water by floating and can make different types of interactions with other organic hydrophobic materials. In addition to that, this hydrophobicity and high “surface area to volume ratio” of microplastics will facilitate most of aqueous heavy metals and other organic compounds. The accumulation of organic contaminants on the plastic surfaces could be several orders of magnitude higher than the surrounding waters.Under laboratory conditions, scientists have proved that there are different sorption values in different organic compounds towards Microplastics. For an example, scientists have shown thatsorption capacities of HOC (Hydrophobic organic contaminants) on microplastics ranging from 1-10,000 ng g-1.
These sorption capacities of different organic materials onto microplastics is determined by different compound specific factors such as polymeric properties and matrix effects (salinity, pH and dissolved organics). Generally non-polar organics have high affinity to non-polar polymers and polar organics have high affinity towards polar polymers showing high sorption capacities.
Other than that various environmental conditions can cause to modify the properties of microplastics. For example, prolonged exposure to sunlight cause the bond breakage of the polymer matrix and subsequent formation of cracks and pores extending the surface area of the particles or fragmentation into smaller particles. As weathering occurs more area will be exposed to oxygen leading to oxidation of chemical groups altering the overall charge.
As mentioned above microplastics adsorb differentpolar and non-polarorganic materials and results in transporting long distances. In environments with low pH, high temperature and low dissolved organic matter, desorption of organicsis promoted. There are much research carried out about sorption of organic materials to microplastics.Studies have confirmed that either via intra-organismal fluidsor direct contact exposure from microplastics adhering to the interior of the organisms,the biotic transfer is accelerated than in the ambient waters.
Further, surfaces of plastic debris,become hosts for various microbial colonies called plastisphere and act as a reservoir to antibiotic and metal resistance genes.
According to data obtain by National Centre for Biotechnology Information Sequence read archive database plastics on ocean debris are act as a reservoir for antibiotic resistance bacteria mentioned earlier and those bacteria contribute to the development of MDR (Multi drug resistant) genes in genes. Bacteria with those genes are called Superbugs. These MDR pathogens pose a huge threat on heath sector in developing antibiotics.For example, due to MDR genes, some superbugs such as MERSA (Methicillin resistant Staphylococcus aureus) have been developed. So, the indirect adverse association between microplastics and health care can be established, reiterating the threats of microplastics on multiple sectors.
It is evident that macroplastics as well as microplastics has already become a huge threat to humans globally as well as locally. Therefore, we should educate the society and gather together to prevent pollution due to this emerging pollutant. The global plastic production is being increased day-by-day. According to the world records, it was estimated that 350 million tons (MT) of plastics had beenproduced in 2017, and it was expected that it would double in the next 20 years. Apart from that 50% of plastic production is recorded in the Asian region while China alone has contributed to 30% of that. Indiscriminate discard and abuse of plastic usage have led to persist microplastics in the environment as well as in organisms for long years resulting in enhanced accumulation. Municipal solid waste contributes to 10%of plastics generated globally. Plastics recycle process recycles only 6-14% of plastics while rest (4.8 – 12.7 MT) is being dumped into aquatic environments such as lakes, rivers and oceans, or landfills.
Today, lightweight and buoyancy assisted plastics debris are scattered in many parts oceans and float, exposing them to physical, chemical, and photolytic degradation for many centuries.
Microplastics are considered to be microscopic particles, including plastic fragments, fibers, or granules associated with polymer materials. Although microplastic is defined in numerous size ranges; generally, it attributes to plastic particles in size range of 100 nm to <5 mm diameter. Microplastics can be identified in two categories, such as primary and secondary.
Primary microplastics are those specifically manufactured in the micrometre size range for different applications in industrial use or in personal care products etc. Secondary microplastics are formed as a result of meso and macroplastic litter fragmentation.
As a result of the exposure to UV radiation, high temperatures, and wave action (in marine environment), most plastics can undergo chemical or physical changes making plastics brittle and thus more susceptible to fragmentation contributing to the formation of microplastics.
All plastics consist of synthetic or semi-synthetic polymers that can be again molded into small particles. Plastics are typically made from organic compounds such as petrochemicals, and these plastics made from long-chain polymers. These majorities of polymers consist of pure carbon chains or with oxygen, nitrogen and sulfur attached to them. To customize the properties of plastics, different molecule groups will hang on the chain backbone. Generally plastics have key properties such as high molecular mass, transparency etc. Plastics can be of few different types, such as Polyethylene Terephthalate (PET or PETE or Polyester), High-Density Polyethylene (HDPE), Polyvinyl Chloride (PVC), Low-Density Polyethylene (LDPE), Polypropylene (PP) and Polystyrene (PS) used in different applications.
The usage of a variety of plastics is varied according to their physical and chemical properties. For example, PET plastic, also known as wrinkled free plastics, are mostly used for food and drink packaging purposes. It is widely used for packaging because it is harder than polythene and also it has the ability to prevent oxygen movement preventing the spoiling of food or drinks inside. It also prevents carbon dioxide in carbonated beverages being released out. Basically PET plastics partials are ubiquitous microplastics found in the sea.
PET plastics are being used ina vast range of products due to its durability and user-friendliness. HDPE is denser and stable than PET because it has a virtually unbranched chemical chains. Due to it higher density and stability, HDPE is commonly used as the grocery bag, opaque milk, juice container, shampoo bottles, and medicine bottle. Even though plastics are considered as a user-friendly and secure packaging option, some studies show that it can leach estrogen-mimicking additives when exposed to UV light. However, PET is considered as the most hazardous plastic because it can release bisphenol A (BPA), phthalates, lead, dioxins, mercury, and cadmium which are carcinogenic.
Likewise, other plastics also cause numerous diseases and disorders.PVC is known as the second widely used plastic variety after PET and commonly used for toys, blister wrap, cling wrap, detergent bottles, loose-leaf binders, blood bags and medical tubing. Some plastics release toxic gases such as methane, carbon dioxide into their environment during their degradation.
Though there are many advantages of different types of plastics, it is evident that most plastics contain carcinogenic substances. These carcinogenic substances can be released into air or water directly or indirectly, depending on the environmental conditions in which these plastics are found.Microplastics have directly used commercially in many products, such as toothpaste, pallets, cosmetics, detergents and etc. Primary microplastics are introduced into the environment through these commercial activities as direct runoff of industrial or through usage as domestic wastewater discharges, contributing directly to environmental pollution. Synthetic microfibres have been identified as the most abundant microplastic particle type found throughout freshwater, terrestrial, and marine environments. Secondary microplastics derived from plastic litter are introduced to the environment mostly through intentional or unintentional releases such as unmanaged municipal, industrial solid waste or individuals creating litter.Urbanization has been observed as one of the most significant factors influencing presence of secondary microplastics in marine environments, with plastics being introduced from a variety of sources including effluent, road runoff, haphazard waste disposal, and atmospheric deposition.
Today, there is much research carried out to identify and quantify microplastics in the environment. Once in the environment, microplastics can quickly enter into the digestive tract of aquatic organisms and then transmitted to other organisms through the food chain. Microplastics are very easy to accumulate in aquatic living organisms because of their size specially particles less than 300 micrometer. Hence, microplastics can easily ingest into marine species specially fishes and other sea animals. Most researchers reported that microplastic fibers are abundantly found in the digestive tract in fishes because most fish nets are made from plastic fibers.
Microplastics also acts as vectors for several substances such as heavy metals and antibiotics.
There are many types of research carried out to investigate the adsorption of heavy metals to microplastics, their flow and transport. Studies have found thatvirgin PVC and Ps (Polystryne) fragments in seawater adsorbs Zn and Cu, leaching from autofouling paint. These heavy metal adsorption to PVC and Ps results in significant implications on the environment and marine life. The microplastic-metal complexes also can then enter human via consumption.
There are some organic compounds that canbe transported attached to microplastics. For example, organic compounds such as antibiotics, persistent organic pollutants (PoP’s),PAHs (Polycyclic aromatic hydrocarbons) and PCBs (Polychlorinated biphenyls) can adsorb microplastic particles via various interactions.PoP’sare producedusing various biosynthetic pathways artificially while sometimes these are also produced naturally through the explosion of volcanos as well. In old days it was used as solvents for different chemicals. They are specially made with halogenic compounds and as a result, become more soluble in lipids. They tend to accumulate in human body, especially in fatty tissues.
Apart from that, they show their negative impacts on the environment through long-range transport, which allows them tore-concentrate in different sources in high levels.Generally, PoPs can be divided into two subsets such as PBTs (Persistent, Bioaccumulative and Toxic) or TOMPs (Toxic Organic Micro Pollutants) based on how it accumulates in the biological bodies.
To make things worse, PoPs resist chemical and photolytic degradation as well. Today, antibiotics and antibiotic-resistant bacterial development is a huge global threat.Antibiotics are one of the major organic compounds responsible foradverse negative effects by bonding with microplastics and results in the development of MDR (multi drug resistant bacteria)superbugs. There are different classes of antibiotics based on their reactive ability to different pathogens.It is well known that excessive amounts of antibiotics will be harmful to our health as well as to our normal gut microflora. There are several beneficial bacteria that live in our gastrointestinal tract. Overuse of antibiotics, can be harmful to our normal gut microflora.
For an example,clostridium difficiale is a severe disease related to gut microfloraresulting in severe pains and diarrhea conditions. There are enough evidenceto say that antibiotics affect adversely for humans as well as terrestrialand aquatic organisms. As antibiotics are chemical organic compounds, degradation of them directly impact the environment especially leading to marine pollution.
It is evident that combination of antibiotics with microplastics will be exert their impact on marine ecosystems. Once these enter the food web even at a remote link, it canadversely affect every individuals even though the induvial does not take an antibiotic. There are some studies revealed that there is high affinity of antibiotics such as amoxicillin, tetracyclin and ciprofloxacin over five different antibiotics to MP. Other than that there are less studies have been carried out about sorption of antibiotics to MP.
PAH’s (Polycyclic aromatic hydrocarbons) are carbon aromatic compounds that can adsorb and make complications with different kinds of microplastics. PAH’s are produced naturally through volcanic activities well as synthetically. Naphthalene is one of the simple double ring aromatic PAH compound while anthracene and phenanthrene have three rings. These aromatic rings can easily get bonded with microplastics through different chemical and physical reactions. Because of these formations and complications on PAH’s and its aromatic rings, they adversely affect human health resulting in mostly respiratory disorders.
In contrast to other organic compounds, PAH’s are found in majority of carbonic compounds in very significant amounts. PCB (Polychlorinated biphenyls) is a type of organic contaminant that also have ability to migrate long distances by binding with microplastics. PCB can be found in everywhere and accumulate into environment through accidental leaks, spills, electricals and other equipmentand improper disposal and storage.Due to its nature, PCB’s can be found in air, land as well as in marine environments. When PCB’s release into whatever the environment, it shows adverse effects by binding to microplastics and migrates long distance like other organic compounds. Further, additives that are added into plastics when they are manufactured for different purposes are persistent organic compounds (POPs) can also flow and transport with microplastics to contaminate virgin natural environments.
As mentioned earlier microplastics are very diverse in all environments because there are various categories of microplastics such as high density polyethylene (HDPE), low density polyethylene (LDPE) and PP (Polypropylene), PET and PVC. Among those, PET and PVC have a higher potential to accumulate in greater concentrations compared to others. All microplastics are hydrophobic and some are organic.
Hence, these can get transported through water by floating and can make different types of interactions with other organic hydrophobic materials. In addition to that, this hydrophobicity and high “surface area to volume ratio” of microplastics will facilitate most of aqueous heavy metals and other organic compounds. The accumulation of organic contaminants on the plastic surfaces could be several orders of magnitude higher than the surrounding waters.Under laboratory conditions, scientists have proved that there are different sorption values in different organic compounds towards Microplastics. For an example, scientists have shown thatsorption capacities of HOC (Hydrophobic organic contaminants) on microplastics ranging from 1-10,000 ng g-1.
These sorption capacities of different organic materials onto microplastics is determined by different compound specific factors such as polymeric properties and matrix effects (salinity, pH and dissolved organics). Generally non-polar organics have high affinity to non-polar polymers and polar organics have high affinity towards polar polymers showing high sorption capacities.
Other than that various environmental conditions can cause to modify the properties of microplastics. For example, prolonged exposure to sunlight cause the bond breakage of the polymer matrix and subsequent formation of cracks and pores extending the surface area of the particles or fragmentation into smaller particles. As weathering occurs more area will be exposed to oxygen leading to oxidation of chemical groups altering the overall charge.
As mentioned above microplastics adsorb differentpolar and non-polarorganic materials and results in transporting long distances. In environments with low pH, high temperature and low dissolved organic matter, desorption of organicsis promoted. There are much research carried out about sorption of organic materials to microplastics.Studies have confirmed that either via intra-organismal fluidsor direct contact exposure from microplastics adhering to the interior of the organisms,the biotic transfer is accelerated than in the ambient waters.
Further, surfaces of plastic debris,become hosts for various microbial colonies called plastisphere and act as a reservoir to antibiotic and metal resistance genes.
According to data obtain by National Centre for Biotechnology Information Sequence read archive database plastics on ocean debris are act as a reservoir for antibiotic resistance bacteria mentioned earlier and those bacteria contribute to the development of MDR (Multi drug resistant) genes in genes. Bacteria with those genes are called Superbugs. These MDR pathogens pose a huge threat on heath sector in developing antibiotics.For example, due to MDR genes, some superbugs such as MERSA (Methicillin resistant Staphylococcus aureus) have been developed. So, the indirect adverse association between microplastics and health care can be established, reiterating the threats of microplastics on multiple sectors.
It is evident that macroplastics as well as microplastics has already become a huge threat to humans globally as well as locally. Therefore, we should educate the society and gather together to prevent pollution due to this emerging pollutant.