Microplastics are fragments of any type of plastic less than 5 mm (0.20 in) in length: U.S. National Oceanic and Atmospheric Administration (NOAA, and the European Chemicals Agency.
Microplastics cause pollution by entering natural ecosystems from a variety of sources, including cosmetics, clothing, food packaging, and industrial processes.
Two classifications of microplastics:
Primary microplastics include any plastic fragments or particles that are already 5.0 mm in size or less before entering the environment: microfibers from clothing, microbeads, and plastic pellets,
Secondary microplastics arise from the degradation of larger plastic products through natural weathering processes after entering the environment: Such sources of secondary microplastics are water and soda bottles, fishing nets, plastic bags, microwave containers, tea bags and tire wear.
Both types are recognized to persist in the environment at high levels, particularly in aquatic and marine ecosystems, where they cause water pollution.
Plastics pollute the environment by ocean currents, atmospheric winds, terrestrial phenomenon, all contributing to their widespread distribution.
35% of all ocean microplastics come from textiles/clothing, primarily due to the erosion of polyester, acrylic, or nylon-based clothing.
The generation of textiles/clothing microplastics occurs, often during the washing process.
Microplastics also accumulate in the air and terrestrial ecosystems.
Plastics degrade slowly, estimated at over hundreds to thousands of years.
Plastics are susceptible to degradation with the formation of micro plastics, defined as particles smaller than 5 mm and nano plastics defined as particles smaller than 1000 nm:both types of particles trigger a range of toxicological effects.
Microplastics and nanoplastics ( MNPs) into the body through ingestion, and halation come and skin exposure where they interact with tissues and organs.
MNPs have been found in placenta, lungs, liver, breast, milk, urine, and blood.
It is suggested that MNP’s, promote oxidative stress, inflammation, and apoptosis in endothelium and other vascular cells, supporting any association between MNPs and cardiovascular disease, with altered heart rate, cardiac function, impairment, my cardio, fibrosis, and endothelial dysfunction.
In terrestrial ecosystems, microplastics reduce the viability of soil ecosystems.
Mcroplastics reduce weight of earthworms.
The cycle and movement of microplastics in the environment are not fully understood.
Deep layer ocean sediment surveys show the presence of plastics in deposition layers far older than the invention of plastics, suggesting underestimation of microplastics in surface sample ocean surveys.
Microplastics have also been found in the high mountains, at great distances from their source.
Microplastics found in human blood, but effects are largely unknown.
In 2014, it was estimated that there are between 15 and 51 trillion individual pieces of microplastic in the world’s oceans, which was estimated to weigh between 93,000 and 236,000 metric tons.
Primary microplastics: E.G.s
Polyethylene based microspherules in toothpaste.
Artificial turf football field with ground tire rubber
Primary microplastics are small pieces of plastic that are purposefully manufactured: used in facial cleansers and cosmetics, or in air blasting technology.
In some medicine as vectors for drugs.
Exfoliating hand cleansers and facial scrubs.
Use in air blasting technology: blasting acrylic, melamine, or polyester microplastic scrubbers at machinery, engines, and boat hulls to remove rust and paint.
Many bioplastic microbeads have a long degradation life cycle similar to normal plastic.
Secondary plastics are small pieces of plastic derived from the breakdown of larger plastic debris.
This occurs both at sea and on land.
Over time the structural integrity of plastic is reduced by physical, biological, and chemphotodegradation, including photo-oxidation caused by sunlight exposure.
The debris formed is at a size that is eventually undetectable to the naked eye.
This process of degradation of large plastic material into much smaller pieces is referred to as fragmentation.
The smallest microplastic size detected in the oceans at present is 1.6 micrometres in diameter.
A myriad of sources of both primary and secondary microplastics are present: Microplastic fibers from the washing of synthetic clothing, tires of synthetic styrene-butadiene rubber, plastic pellets, used to create other plastic products.
Nanoplastics are less than 1 μm or less than 100 nm in size.
Nanoplastics relate to risks to environmental and human health.
Nanoplastics size, allow them to cross cellular membranes and affect the functioning of cells.
They are lipophilic and can be incorporated into the hydrophobic core of lipid bilayers.
Little is known on adverse health effects of nanoplastics.
In patients with carotid artery plaque in which micro plastics and nano plastics(MNPs) were detected, had a higher risk of myocardial infarction, stroke, or death from any cause at 34 months of follow up than those in whomMNP’s were not detected (Marfella R).
Most microplastic pollution comes from textiles, tires and city dust which account for over 80% of all microplastic in the environment.
Microplastics in the environment is often established by aquatic studies: plankton samples, sandy and muddy sediments, observing vertebrate and invertebrate consumption, and evaluating chemical pollutant interactions.
Microplastics could contribute up to 30% pollution the world’s oceans and, in many developed countries, are a bigger source of marine plastic pollution than the visible larger pieces of marine litter.
Wear and tear from tires significantly contributes to the flow of microplastic pollution into the environment.
Secondary microplastics from car and truck tires or footwear are more important than primary microplastics by two orders of magnitude.
The estimated per capita emission ranges from 0.23 to 4.7 kg/year, with a global average of 0.81 kg/year.
The emissions from car tires, reaching 100%, are substantially higher than those of other sources of microplastics, airplane tires (2%), artificial turf (wear 12–50%), brakes (wear 8%), and road markings (wear 5%).
Road markings are protected by a layer of glass beads and their contribution constitutes approximately 0.7% of all of the secondary microplastics emissions.
The relative contribution of tire wear and tear to the total global amount of plastics ending up in our oceans is estimated to be 5–10%.
In air, 3–7% of the particulate matter (PM2.5) is estimated to consist of tire wear and tear, indicating that it may contribute to the global health burden of air pollution which has been projected by the World Health Organization (WHO) at 10 million deaths in 2019.
Pollution from tire wear and tear also enters the food chain.
Many synthetic fibers, such as polyester, nylon, acrylics, and spandex, can be shed from clothing and persist in the environment.
Each garment in a load of laundry can shed more than 1,900 fibers of microplastics, with fleeces releasing the highest percentage of fibers, over 170% more than other garments.
For an average wash load of 6 kilograms (13 lb), over 700,000 fibers could be released per wash.
These microfibers have been found to persist throughout the food chain.
The primary fiber that persist throughout the textile industry is polyester.
Polyester types of fibers contribute greatly to the persistence to microplastics in terrestrial, aerial, and marine ecosystems.
The process of washing clothes causes garments to lose an average of over 100 fibers per liter of water.
These types of fibers in households has been shown to represent 33% of all fibers in indoor environments.
Textile fibers: indoor exposures are 1.0–60.0 fibers/m3, whereas the outdoor concentration is at 0.3–1.5 fibers/m3.
The deposition rate indoors was 1586–11,130 fibers per day/m3 which accumulates to around 190-670 fibers/mg of dust.
These concentrations of fibers results in increased exposure to children and the elderly, which can cause adverse health effects.
Natural exfoliating ingredients have been replaced with microplastics, usually in the form of microbeads or micro-exfoliates. typically composed of polyethylene, a common component of plastics, but they can also be manufactured from polypropylene, polyethylene terephthalate, and nylon.
These microplastic beads are often found in face washes, hand soaps, and other personal care products, and are usually washed into the sewage system immediately after use.
Their small size allows some to enter rivers and oceans, as wastewater treatment plants only remove an average of 95–99.9% of microbeads because of their small design .
There is an average of 0–7 microbeads per litre being discharged: one treatment plant discharges 160 trillion liters of water per day, around 8 trillion microbeads are released into waterways every day.
This number does not account for the sewage sludge that is reused as fertilizer, and known to still contain these microbeads.
Microbead discharge has a negative impact upon the wildlife and food chain, but also upon levels of toxicity, as microbeads have been proven to absorb dangerous chemicals such as pesticides and polycyclic aromatic hydrocarbons.
There are more than 500 microplastic ingredients that are widely used in cosmetics and personal care products.
Recreational and commercial fishing, marine vessels, and marine industries are sources of plastic that can directly enter the marine environment, posing a risk as macroplastics, and as secondary microplastics following long-term degradation.
Marine debris arises from beaching of materials carried on inshore and ocean currents.
Fishing gear is a form of plastic debris with a marine source.
Discarded or lost fishing gear, including plastic monofilament line and nylon netting is typically buoyant and can, drift at variable depths within the oceans.
Microplastics from the industry and other sources have been accumulating in different types of seafood and therefore the food chain.
It is not just the plastics that are being transferred through the food chain but the chemicals from the plastics as well.
The manufacture of plastic products uses granules and small resin pellets as their raw material and they can enter aquatic ecosystems.
Many industrial sites in which raw plastics are frequently used are located near bodies of water.
Shipping has significantly contributed to marine pollution.
Since 1988 an international agreement prohibited the dumping of waste from ships into the marine environment.
In the United States, the Marine Plastic Pollution Research and Control Act of 1987 prohibited discharge of plastics in the sea, including from naval vessels.
Approximately 10% of the plastic found on the beaches in Hawaii are nurdles, the building blocks of microplastics.
The increase in production, consumption, and littering of face masks adds to the list of environmental challenges, due to the addition of microplastic particle waste in the environment, emerging a new source .
More than 93% of the bottled water from 11 different brands showed microplastic contamination.
Compared to tapwater, water from plastic bottles contained twice as much microplastic.
Polypropylene infant feeding bottles with contemporary preparation procedures were found to cause microplastics exposure to infants ranging from 14,600 to 4,550,000 particles per capita per day.
Microplastics release is higher with warmer liquids and similar with other polypropylene products such as lunchboxes.
Silicone rubber baby bottle nipples degrade over time from repeated steam sterilization, shedding micro- and nano-sized particles of silicone rubber.
It estimated that, using such heat-degraded nipples for a year, a baby will ingest more than 660,000 microplastic particles.
Paper coffee cups release many nanoplastics into water.
Single-use plastic products, such as paper coffee cups that are lined with a thin plastic film inside, release trillions of microplastic-nanoparticles per liter into water during normal use, and enter aquatic environments.
Sewage treatment plants, (wastewater treatment plants (WWTPs), remove contaminants from wastewater, primarily from household sewage, using various physical, chemical, and biological processes.
There are generally 3 stages in sewage treatment processing.
In the primary stage of treatment, physical processes are used to remove oils, sand, and other large solids using conventional filters, clarifiers, and settling tanks.
Secondary treatment uses biological processes involving bacteria and protozoa to break down organic matter.
The optional tertiary treatment stage may include processes for nutrient removal of nitrogen and phosphorus and disinfection.
Microplastics are detected in both the primary and secondary treatment stages of the plants.
About one particle per liter of microplastics are being released back into the environment, with a removal efficiency of about 99.9%.
The contribution of microplastics into oceans and surface water environments from WWTPs is not disproportionately large.
Sewage sludge is used for soil fertilizer in some countries, and
It exposes plastics in the sludge to the weather, sunlight, and other biological factors, causing fragmentation.
The microplastics from these biosolids often end up in storm drains and eventually into bodies of water.
Sludge disposal sites contain an average one particle of microplastic per liter. A
A significant amount of these particles was of clothing fibers from washing machine effluent.
Some microplastics pass through filtration processes at some WWTPs.
Microplastics are now present in every part of the environment.
Microplastics are not as conspicuous as larger plastic, being less than 5 mm, and are usually invisible to the naked eye.
Particles of this size are available to a much broader range of marine species, enter the food chain at the bottom, become embedded in animal tissue, and are then undetectable by unaided visual inspection.
The large amounts of plastic currently in the environment undergoing degradation, but that has many more years of decay to release of toxic compounds: referred to as toxicity debt.
Microplastics have been detected not just in marine but also in freshwater systems including marshes, streams, ponds, lakes, and rivers..
Microplastics can be imbeddeded in animals’ tissue through ingestion or respiration.
Some coral have also been found to ingest microplastics.
It can take up to 14 days for microplastics to pass through an animal.
When microplastic-laden animals are consumed by predators, the microplastics are then incorporated into the bodies of higher trophic-level feeders.
Bottom feeders, who are non-selective scavengers that feed on debris on the ocean floor, ingest large amounts of sediment with microplastic content.
Bivalves, are aquatic filter feeders, have also been shown to ingest microplastics and nanoplastics.
Upon exposure to microplastics, bivalve filtration ability decreases.
Multiple cascading effects occur as a result, such as immunotoxicity and neurotoxicity in bivalves.
When exposed to microplastics, bivalves also experience oxidative: stress when exposed to microplastics
indicating an impaired ability to detoxify compounds within the body, which can ultimately damage DNA.
Bivalve gametes and larvae are also impaired when exposed to microplastics, and rates of developmental arrest, and developmental malformities increase, while rates of fertilization decrease.
Scleractinian corals, which are primary reef-builders, have been shown to ingest microplastics.
Microplastics have been shown to stick to the exterior of the corals after exposure increasing the likelihood of mortality.
Three-quarters of the underwater seagrass have microplastic fibers, indicating microplastics arenon aquatic vascular plants.
Microplastics can stunt the growth of terrestrial plants and earthworms.
There is an emerging issue of plastics is a threat even in remote high-altitude environments.
Zooplankton ingest microplastics beads and excrete fecal matter contaminated with microplastics, and they stick to their appendages and exoskeletons.
Green and red filaments of plastics are found in the planktonic organisms and in seaweeds.
Some microbes live on the surface of microplastics. forming a slimy biofilm proven to provide a novel habitat for colonization that increases overlap between different species.
This process spreads pathogens and antibiotic resistant genes through horizontal gene transfer.
Human health risks of nano- and microplastics, is known is uncertain.
Mean/median intake of microplastics in humans are at levels considered to be safe in humans.
It is unknown whether and to what degree microplastics accumulate in humans.
Research reported the presence of polymers in human blood in 17 of 22 healthy volunteers.
The microplastics ingested by fish and crustaceans can be subsequently consumed by humans as the end of the food chain.
Microplastics are found in air, water, and food that humans eat, especially seafood; however, the degree of absorption and retention is unclear.
Microplastics might complex with heavy metals or other chemical compounds in the environment and act as a vector for bringing them into the body, and it is possible that microplastics might serve as vectors for pathogens.
Plastic particles may highly concentrate and transport synthetic organic compounds commonly present in the environment and ambient seawater, on their surface through adsorption.
Microplastics can absorb emerging organic chemicals such as pharmaceuticals and personal care products.
Additives added to plastics during manufacture may leach out upon ingestion, potentially causing serious harm to the organism.
Endocrine disruption by plastic additives may affect the reproductive health of humans and wildlife alike.
Plastics, polymers derived from mineral oils, are virtually non-biodegradable.
Airborne microplastics have been detected in the atmosphere, as well as indoors and outdoors.
Microplastic to be atmospherically transported to remote areas on the wind.
A study found indoor airborne microfiber concentrations between 1.0 and 60.0 microfibers per cubic meter, one third of which were microplastics.
Microplastics and microfibers were also found in snow samples, in high mountains at vast distances from their source.
Microplastics have been widely detected in the world’s aquatic environments.
Microplastics are present in all of the Great Lakes with an average concentration of 43,000 MP particle km−2.
Most are plastic microfibers resulting from the breakdown of larger particles, synthetic textiles, or atmospheric fallout.
The highest concentration of microplastic ever discovered in a studied freshwater ecosystem was recorded in the Rhine river.
A substantial portion of microplastics are expected to end up in the world’s soils.
Wetland environment microplastic concentrations have a negative correlation with vegetation cover and stem density.
Secondary microplastics from washing machines could end up in soil through the failure of water treatment plants to completely filter out all of the microplastic fibers.
Geophagous soil fauna, such as earthworms, and mites could contribute to secondary microplastic presence in soil by converting consumed plastic debris into microplastic via digestive processes.
Microplastics ultimately find their way into food, water and the air humans are exposed to.
It is estimated people consume more than 50,000 plastic particles per year, and many more if inhalation is considered.
Microplastics were found in every human tissue.
Microplastics have also been found in 80% of anonymous blood samples, meaning they can be transported around the human body and raising the question of whether they can be transported to the brain.
Microplastic particles have been found in the placentas of unborn babies.
Plastic pollution is having the greatest impacts on the world’s poorest and most vulnerable populations, as these groups predominantly work in the informal waste sector and/or live in the vicinities of open dumpsites.
Plastic pollution directly and indirectly threatens their human rights, including the rights to life, health, water and sanitation, food, housing, culture and development.
Treatment
Some researchers have proposed incinerating plastics to use as energy.
Recycling plastics is considered a more efficient solution.
Biodegradation as a solution to large amounts of microplastic waste: microorganisms consume and decompose synthetic polymers by means of enzymes.
These plastics can then be used in the form of energy and as a source of carbon once broken down.
Stormwater or wastewater collection systems can capture many microplastics which are transported to treatment plants, the captured microplastics become part of the sludge produced by the plants.
This sludge is often used as farm fertilizer meaning the plastics enter waterways through runoff.
experts, though it has seen wide public support.[167][168][169]
Degrading microplastics, microbes had been engineered in a novel way to capture microplastics in their biofilm matrix from polluted samples for easier removal of such pollutants.
Recycling is another proposed solution for microplastic contamination.
To reduce littering, especially in urban environments where there are often large concentrations of plastic waste.
A cycle of plastic use and reuse would be created to decrease our waste output and production of new raw materials.
The Yangtze River in China contributes 55% of all plastic waste going to the seas.
The Yangtze bears an average of 500,000 pieces of plastic per square kilometer.[l
China dumps 30% of all plastics in the ocean.