"Plastic Pollution: A Modern Environmental Catastrophe"
plastic pollution, accumulation in the environment of synthetic plastic products to the point that they create problems for wildlife and their habitats as well as for human populations.
In 1907 the invention of Bakelite brought about a revolution in materials by introducing truly synthetic plastic resins into world commerce. By the end of the 20th century, plastics had been found to be persistent polluters of many environmental niches, from Mount Everest to the bottom of the sea. Whether being mistaken for food by animals, flooding low-lying areas by clogging drainage systems, or simply causing significant aesthetic blight, plastics have attracted increasing attention as a large-scale pollutant.
Plastic pollution in oceans and on land
In the ocean, plastic pollution can kill marine mammals directly through entanglement in objects such as fishing gear, but it can also kill through ingestion, by being mistaken for food. Studies have found that all kinds of species, including small zooplankton, large cetaceans, most seabirds, and all marine turtles, readily ingest plastic bits and trash items such as cigarette lighters, plastic bags, and bottle caps. Sunlight and seawater embrittle plastic, and the eventual breakdown of larger objects into microplastics makes plastic available to zooplankton and other small marine animals. Such small pieces of plastic, which are less than 5 mm (0.2 inch) in length, make up a sizable fraction of plastic waste in the oceans. By 2018, microplastics had been found in the organs of more than 114 aquatic species, including some species found only in the deepest ocean trenches. By 2020, scientists had estimated that at least 14 million metric tons (15.4 million short tons) of microplastic particles were resting on the floor of the ocean, and other research had revealed that the movement of deep-sea currents was creating microplastic “hot spots” in parts of the oceans, such as one located in the Tyrrhenian Sea that contained nearly two million microplastic pieces per square metre (about 186,000 pieces per square foot).
There are also terrestrial aspects to plastic pollution. Drainage systems become clogged with plastic bags, films, and other items, causing flooding. Land birds, such as the reintroduced California condor, have been found with plastic in their stomachs, and animals that normally feed in waste dumps—for instance, the sacred cows of India—have had intestinal blockages from plastic packaging. The mass of plastic is not greater than that of other major components of waste, but it takes up a disproportionately large volume. As waste dumps expand in residential areas, the scavenging poor are often found living near or even on piles of residual plastics. In addition, wind-transported microplastic fibres and particles have been detected in many parts of the world, including the snow deposited high atop mountains, on Arctic beaches and sea ice, and in Antarctica.
Pollution by plastics additives
Plastic also pollutes without being littered—specifically, through the release of compounds used in its manufacture. Indeed, pollution of the environment by chemicals leached from plastics into air and water is an emerging area of concern. As a result, some compounds used in plastics, such as phthalates, bisphenol A (BPA), and polybrominated diphenyl ether (PBDE), have come under close scrutiny and regulation. Phthalates are plasticizers—softeners used to make plastic products less brittle. They are found in medical devices, food packaging, automobile upholstery, flooring materials, and computers as well as in pharmaceuticals, perfumes, and cosmetics. BPA, used in the manufacture of clear, hard polycarbonate plastics and strong epoxy coatings and adhesives, is present in packaging, bottles, compact discs, medical devices, and the linings of food cans. PBDE is added to plastics as a flame retardant. All these compounds have been detected in humans and are known to disrupt the endocrine system. Phthalates act against male hormones and are therefore known as anti-androgens; BPA mimics the natural female hormone estrogen; and PBDE has been shown to disrupt thyroid hormones in addition to being an anti-androgen. The people most vulnerable to such hormone-disrupting chemicals are children and women of reproductive age.
These compounds have also been implicated in hormone disruption of animals in terrestrial, aquatic, and marine habitats. Effects are seen in laboratory animals at blood levels lower than those found in the average resident of a developed country. Amphibians, mollusks, worms, insects, crustaceans, and fish show effects on their reproduction and development, including alterations in the number of offspring produced, disruption of larval development, and (in insects) delayed emergence—though studies investigating resulting declines in those populations have not been reported. Studies are needed to fill this knowledge gap, as are studies of the effects of exposure to mixtures of those compounds on animals and humans.
Conclusion
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