Microplastic litter poses a special threat to the world’s oceans and human health
The microplastic ingested by this three-millimeter-long sea flea are visible by their greenish glow. In a laboratory, fleas were exposed to spheres and irregular fragments in amounts greater than those present in nature. The irregular pieces of microplastics involve more danger because they can get stuck in the intestine. Fish caught by children near a fish farm in Manila Bay, in the Philippines, live in an ecosystem contaminated by household waste, microplastic, and other garbage. It is ignored if the microplastics ingested by the fish affect the humans who consume them, but the scientists look for the answers.
Microplastic is a threat to human health:-
In a laboratory at the Lamont-Doherty Earth Observatory at Columbia University in Palisades, New York, Debra Lee Magadini places a slide in the microscope and lights an ultraviolet lamp. As he scrutinizes the liquefied digestive tract of a shrimp he has acquired in a fish market, he exclaims:Across the planet, researchers like Magadini sit before the microscope and detect tiny microplastic particles – fibers, fragments or microbeads – that have reached the interior of fresh and saltwater species, both wild and aquaculture. Scientists have found micro-plastics in 114 aquatic species, and more than half of them are common in our diet. Now they are trying to determine if it has any consequences for human health. To date, there is no scientific evidence that microplastic – fragments of less than five millimeters – are affecting ichthyofauna at the population level. Our food source doesn’t seem to be in danger unless we know. But what has been sufficiently demonstrated is that the fish and seafood we taste are not immune to the omnipresence of plastic. Every year between five and 13 million tons of plastic reach our seas from the coast. The sun, wind, waves, and heat break down that material into smaller pieces, which plankton, bivalves, fish and even whales confuse with food. Experiments show that microplastics cause damage to aquatic fauna, as well as turtles and birds: they cause intestinal obstructions and reduce their desire to eat, which cuts back on their growth and reproductive performance. With a stomach full of microplastic, some species stop feeding and die.
Chelsea Rochman, an ecology professor at the University of Toronto, dipped powdered polyethylene – a material with which some plastic bags are made – for three months in San Francisco Bay. He then offered this contaminated plastic, for two months and together with a laboratory diet, to some Japanese medakas, some fish commonly used in research. Those who ingested this plastic suffered greater liver damage than those who consumed unpolluted plastic.(Fish that have compromised liver function have a harder time metabolizing drugs, pesticides, and other water contaminants.) Another experiment showed that oysters exposed to polystyrene microparticles – the material in takeaway food containers – produce fewer eggs and less mobile sperm. The list of freshwater and marine organisms harmed by microplastics includes hundreds of species.
Hormonal problems cause due to Microplastic:-
Some of these substances are considered endocrine disruptors, that is, compounds that interfere with the hormonal system. Fire retardants can interfere with the brain development of fetuses and children; other compounds that adhere to microplastics can cause cancer or congenital malformations. A basic tenet of toxicology is that the toxicity depends on the dose, but many of these substances seem to harm laboratory animals at levels that some countries consider safe for humans. Studying the impact of marine microplastics on human health is complicated because no one can be asked to ingest plastic as an experiment, because plastics and their additives act differently according to physical and chemical circumstances, and because their characteristics can vary according to beings along the food chain ingest, metabolize or excrete. We barely know anything that happens with the toxicity of microplastics contained in aquatic organisms when we cook or process them, or what level of contamination could harm us.
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