Microplastics

Microplastics, small pieces of plastic, less than 5 mm (0.2 inches) in length, that occur in the environment as a consequence of plastic pollution. Microplastics are present in a variety of products, from cosmetics to synthetic clothing to plastic bags and bottles. Many of these products readily enter the environment in wastes.

1. MICROPLASTICS P Madhusudana Patra Research Scholar Department of Zoology Presidency College CHENNAI-5

2. MICROPLASTICS Definition: M icroplastics  are not a specific kind of plastic these are small, barely visible pieces of plastic. T hese are plastic fragments that are less than 5mm in length (U.S. National Oceanic and Atmospheric Administration (NOAA)). 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. Plastics degrade slowly, often over hundreds if not thousands of years. This increases the probability of microplastics being ingested and incorporated into, and  accumulated  in, the bodies and tissues of many organisms.

3. CLASSIFICATION Primer Microplastics Secondary M icroplastics

4. PRIMER MICROPLASTICS Primary microplastics are small pieces of plastic that are purposefully manufactured, THESE plastic fragments or particles that are already 5.0 mm in size or less before entering the environment. Sources including personal care products, such as toothpastes, shampoos, shower gels and fibers from laundry. In some cases these are used in medicine as a vector for drugs Primary microplastics have also been produced for use in air blasting technology. This process involves blasting  acrylic ,  melamine , or  polyester   microplastic scrubbers at machinery, engines, and boat hulls to remove rust and paint. Washing synthetic clothing and fabrics may release microplastic fibers in wastewater, it has been shown that a single polyester fleece jacket can release >1900 fibers per wash ( bowne et al., 2011). Approximately 90% of microplastics may be retained in wastewater treatment plants ( ziajaharomi at al.,2016).

5. Secondary microplastics Secondary plastics are small pieces of plastic derived from the breakdown of larger plastic debris, both at sea and on land. Over time, a culmination of physical, biological, and chemphotodegradation , including photodegradation caused by sunlight exposure, can reduce the structural integrity of plastic debris and causes development of secondary microplastics . This process of breaking down large plastic material into much smaller pieces is known as fragmentation. Sources of secondary microplastics include water and soda bottles, fishing nets, and plastic bags. Both types are recognized to persist in the environment at high levels, particularly in aquatic and  marine ecosystems .

6. Where microplastics can be found? Oceans There is truly a staggering amount of microplastics in our world’s oceans. A 2015 study estimated that there was between 93 and 236 thousand metric tons of microplastics in the world’s oceans. The study, using data on surface plastic concentration (pieces of plastic km -2 ) from 1972-1985 n=60 and 2002-2012 n=457 within the same plastic accumulation zone, found the mean plastic concentration increase between the two sets of data, including a 10-fold increase of 18,160 to 189,800 pieces of plastic km -2 .

7. Freshwater ecosystems Though there have only been a few studies of microplastics in freshwater ecosystems, microplastics are being increasingly detected in the world’s aquatic environments. The first study on microplastics in freshwater ecosystems was published in 2011 that found an average of 37.8 fragments per square meter of lake huron sediment samples. Additionally, studies have found mp ( microplastic ) to be present in all of the great lakes with an average concentration of 43,000 mp particle km -2 . The highest concentration of microplastic ever discovered in a studied freshwater ecosystem was recorded in the rhine river at 4000 mp particles kg -1 .

8. Soil A substantial portion of microplastics are expected to end up in the world’s soil, yet very little research has been conducted on microplastics in soil. Some speculation that fibrous 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, mites, and collembolan could contribute to the amount of secondary microplastic present in soil by converting consumed plastic debris into microplastic via digestive processes.

9. In the air Airborne microplastics have been detected in the  atmosphere , as well as indoors and outdoors. A 2017 study found indoor airborne microfiber concentrations between 1.0–60.0 microfibers per cubic meter (33% of which were found to be microplastics ). Another study looked at microplastic in the street dust of  tehran  and found 2,649 particles of microplastic within 10 samples of street dust, with ranging samples concentrations from 83 particle – 605 particles (+/- 10) per 30.0 g of street dust. However, much like freshwater ecosystems and soil, more studies are needed to understand the full impact and significance of airborne microplastics .

10. How does microplastics enter the environment? Remove contaminants from wastewater, primarily from household sewage, using various physical, chemical, and biological processes. Most plants in developed countries have both  primary  and  secondary treatment  stages. In the primary stage of treatment , physical processes are employed to remove oils, sand, and other large solids using conventional filters,  clarifiers , and settling tanks. [22] Secondary treatment uses biological processes involving  bacteria  and  protozoa  to break down organic matter. Microplastics have been detected in both the primary and secondary treatment stages of the plants. A study estimated that about one particle per liter of microplastics are being released back into the environment, with a removal efficiency of about 99.9%. BEST WAY: Certain countries sewage sludge is used for soil fertilizer, which exposes plastics in the sludge to the weather, sunlight, and other biological factors, causing fragmentation. As a result, microplastics from these biosolids often end up in storm drains and eventually into bodies of water . Sewage treatment plants The existence of microplastics in the environment is often established through aquatic studies. These include taking  plankton  samples, analyzing sandy and muddy  sediments , observing  vertebrate  and  invertebrate  consumption, and evaluating chemical  pollutant interactions . [20]  Through such methods, it has been shown that there are microplastics from multiple sources in the environment. SOURCES

11. Car and truck tires Wear and tear from tires significantly contributes to the flow of (micro-)plastics into the environment. In  denmark between  5,500 and 14,000 tonnes (6,100 and 15,400 tons) of microplastics emissions to the environment  per year. Secondary microplastics ( e.G. 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 (100%) are substantially higher than those of other sources of microplastics , e.G. , Airplane tires (2%), artificial turf (12–50%), brake wear (8%), and road markings (5%).

12. Cosmetics industry Some companies have replaced natural  exfoliating  ingredients with microplastics , usually in the form of " microbeads " or "micro-exfoliates". These products are typically composed of  polyethylene , a common component of plastics, but they can also be manufactured from  polypropylene ,  polyethylene terephthalate , and  nylon . They are often found in face washes,  hand soaps , and other personal care products, so the beads are usually washed into the  sewage  system immediately after use. It has been estimated that around 808 trillion beads per household are discharged in a single day whether due to cosmetic exfoliates, face wash, toothpaste, or other sources. This fact contributes to the total of 80 metric tons of microbeads discharge per year just by the united kingdom alone. This not only has a negative impact on the wildlife and food chain but also in terms of toxicity because plastics such as microbeads have been proven to absorb dangerous chemicals such as pesticides and polycyclic aromatic hydrocarbons.

13. CLOTHING Studies have shown that many synthetic fibers, such as polyester, nylon and acrylics, 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. The process of washing clothes causes garments to lose an average of over 100 fibers per liter of water. Anthropomorphic fibers have been studied in both indoor and outdoor environments to study the concentration of these to see what the average human exposure to microfibers look like. The indoor concentration was 1.0–60.0 fibers/m^3 whereas the outdoor concentration was much lower at 0.3-1.5 fibers/m^3.

14. Manufacturing The manufacture of plastic products uses  granules  and small  resin  pellets as their raw material. In the united states, production increased from 2.9 million pellets in 1960 to 21.7 million pellets in 1987. Through accidental spillage during land or sea transport, inappropriate use as  packing materials , and direct outflow from processing plants, these raw materials can enter  aquatic ecosystems . . In an assessment of  swedish  waters using an 80 µm mesh, kimo sweden found typical microplastic concentrations of 150–2,400 microplastics per m 3 ; in a harbor adjacent to a plastic production facility, the concentration was 102,000 per m 3 . . In an assessment of  swedish  waters using an 80 µm mesh, kimo sweden found typical microplastic concentrations of 150–2,400 microplastics per m 3 ; in a harbor adjacent to a plastic production facility, the concentration was 102,000 per m 3 . [15]

15. Fishing industry Recreational  and  commercial fishing ,  marine vessels , and marine industries are all sources of plastic that can directly enter the marine environment, posing a risk to biota both as macroplastics , and as secondary microplastics following long-term degradation.  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 neutrally  buoyant  and can, therefore, drift at variable depths within the oceans.

16. Packaging and shipping Shipping  has significantly contributed to marine pollution. Some statistics indicate that in 1970, commercial shipping fleets around the world dumped over 23,000 tons of plastic waste into the marine environment. In 1988, an international agreement ( marpol 73/78 , annex v) prohibited the dumping of waste from ships into the marine environment. However, shipping remains a dominant source of  plastic pollution , having contributed around 6.5 million tons of plastic in the early 1990s. CASE STUDY : On july 24th, 2012, 150 tonnes of nurdles and other raw plastic material spilled from a shipping vessel off the coast near  hong kong  after a major storm. This waste from the chinese company  sinopec  was reported to have piled up in large quantities on beaches. While this is a large incident of spillage, researchers speculate that smaller accidents also occur and further contribute to marine microplastic pollution.

17. Plastic water bottles In one study, 93% of the bottled water from 11 different brands showed microplastic contamination. Per liter, researchers found an average of 325 microplastic particles. Of the tested brands, nestlé pure life and gerolsteiner bottles contained the most microplastic with 930 and 807 microplastic particles per liter ( mpp /l), respectively. San pellegrino products showed the least quantity of microplastic densities. Compared to water from taps, water from plastic bottles contained twice as much microplastic . Some of the contamination likely comes from the process of bottling and packaging the water.

18. Biological integration into organisms Microplastics can become embedded in animal’s tissue through ingestion or respiration . ANNELID Various annelid species, such as deposit-feeding  lugworms  ( arenicola marina ), have been shown to have microplastics embedded in their  gastrointestinal tracts . CRUSTACEANS Many  crustaceans , like the shore crab  carcinus maenas , have been seen to integrate microplastics into both their respiratory and digestive tracts. SEA CUCUMBER Bottom feeders , such as  benthic   sea cucumbers , who are non-selective scavengers that feed on debris on the ocean floor, ingest large amounts of sediment. It has been shown that four species of sea cucumber ( thyonella gemmate ,  holothuria floridana ,  H. Grisea  and  cucumaria frondosa ) ingested between 2- and 20-fold more PVC fragments and between 2- and 138-fold more nylon line fragments (as much as 517 fibers per organism) based on plastic-to-sand grain ratios from each sediment treatment. CORAL REEF Not only fish and free-living organisms can ingest microplastics .  Scleractinian corals , which are primary reef-builders, have been shown to ingest microplastics under laboratory conditions. The adherence to the outside of corals can potentially be harmful, because corals cannot handle sediment or any particulate matter on their exterior and slough it off by secreting mucus, and they expend a large amount of energy in the process, increasing the chances of mortality

19. ZOOPLANKTON Zooplankton  ingest microplastics beads (1.7–30.6 μm ) and excrete fecal matter contaminated with microplastics . Along with ingestion, the microplastics stick to the appendages and exoskeleton of the zooplankton. [56]  zooplankton, among other marine organisms, consume microplastics because they emit similar infochemicals , notably  dimethyl sulfide , just as  phytoplankton  do. It can take at least 14 days for microplastics to pass through an animal (as compared to a normal digestion periods of 2 days), but enmeshment of the particles in animals'  gills can prevent elimination entirely. Scientists have reported plastic accumulation in the stomachs of  lantern fish  which are small filter feeders and are the main prey for commercial fish like  tuna  and  swordfish .

20. effect on the environment According to a comprehensive review of scientific evidence published by the  European Union 's  Scientific Advice Mechanism  in 2019, microplastics are now present in every part of the environment. While there is no evidence of widespread ecological risk from microplastic pollution yet, risks are likely to become widespread within a century if pollution continues at its current rate.

21. MARINE HEALTH Scientists have documented over  600 species  impacted by plastic marine debris. The majority of this debris causes harm by ingestion. As plastic debris floats around in the ocean, they pick up algae and odors that  mimic the smell  of food, attracting marine animals to eat them. Plastics build up in the animal’s digestive system, causing blockages and starvation. They also leach toxins that can stress organ function. Plastic is also good at collecting   pbts , and toxic chemicals such as ddt that persist in the environment even when they are no longer used. As microplastics float around the ocean, they easily collect pbts . When marine animals ingest plastic, they ingest pbts , which  bioaccumulate  in their tissues. When we eat fish, we also eat most of the toxins they’ve ingested in their lifetime.

22. HUMAN HEALTH Fish is a significant source of  protein  for the human population, accounting for 6.1% of all protein consumed globally in 2007. The microplastics ingested by fish and crustaceans can be subsequently consumed by humans as the end of the  food chain . In a study done at the state university of new york , 18 fish species were sampled and all species showed some level of plastics in their systems. . It has also been thought that microplastics can act as a vector for pathogens as well as heavy metals . More specifically, pregnant women in particular are in danger of causing birth defects to male infants such as anogenital distance, penile width, and testicular descent. Bpa is a commonly well-known substance that is an ingredient used to harden plastic that can also cause a wide range of disorders. Cardiovascular disease, type 2 diabetes, and abnormalities in liver enzymes are a few disorders that can arise from even small exposure to this chemical.

23. CONT… Tetrabromobisphenol a ( tbbpa ) which is a flame retardant in many different types of plastics such as those used in microcircuits. This chemical has been linked to disruptions in thyroid hormones balance, pituitary function, and infertility . Tetrabromobisphenol A (TBBPA) which is a flame retardant in many different types of plastics such as those used in microcircuits. This chemical has been linked to disruptions in thyroid hormones balance, pituitary function, and infertility. The endocrine system is affected by TBBPA through disruption of the natural T3 functions with the nuclear suspension in pituitary and thyroid. An example of bioaccumulation in the food chain that leads to human exposure was a study done into the tissue samples of mussels to approximate concentration of microplastics . After research scientists estimate that an average citizen might be exposed to 123 MP articles/year/capita of microplastics through mussel consumption in the UK. A 2018 study conducted on eight individuals from europe and japan found microplastics in   human feces   for the first time. All participants were found positive for at least one type of microplastics after all of them had consumed plastic-wrapped food and drunk water from plastic bottles while six had also eaten seafood.

24. Proposed solutions USE AS ENERGY Some researchers have proposed incinerating plastics to use as energy, which is known as energy recovery. As opposed to losing the energy from plastics into the atmosphere in  landfills , this process turns some of the plastics back into energy that can be used. Recycling plastics is considered a more efficient solution. PUBLIC AWARENESS ABOUT RECYCLING Increasing education through recycling campaigns is another proposed solution for microplastic contamination. Especially in urban environments where there are often large concentrations of plastic waste. If recycling efforts are increased, a cycle of plastic use and reuse would be created to decrease our waste output and production of new raw plastics .

25. Biodegradation In this process, microorganisms consume and decompose synthetic polymers with using degrading enzymes. These plastics can then be used in the form of energy and as a source of  carbon  once broken down. The microbes could potentially be used to treat sewage wastewater, which would decrease the amount of microplastics that pass through into the surrounding environments.