Science and Technology ** Beijing, January 9, researchers from Columbia University's School of Climate in the United States for the first time counted and identified tiny plastic particles in bottled water. It was found that the average litre of water contained about 240,000 detectable microplastics, which was 10 to 100 times higher than previous counts, which were mainly based on larger microplastics. The study was published in the Proceedings of the National Academy of Sciences on the 8th.
Microplastics are defined as fragments ranging in size from 5 mm to 1 micron. For reference, a human hair is about 70 microns in diameter. Nanoplastics are particles smaller than 1 micron and measured in billionths of a meter. Nanoplastics can pass through the intestines and lungs directly into the bloodstream, and from there reach organs including the heart and brain. They can invade individual cells and enter the unborn baby through the placenta.
Nearly 400 million tonnes of plastic are produced globally every year, and more than 30 million tonnes of plastic waste is dumped in water or on land. Many products made of plastic produce tiny particles during use. Unlike natural organic matter, most plastics do not break down into relatively harmless substances. They simply break down into smaller and smaller particles of the same chemical composition. With the exception of single molecules, there is theoretically no limit to how small they can become.
The new study used stimulated Raman scattering microscopy techniques. For seven common plastics, the researchers created a data-driven algorithm to interpret the results. They tested 3 popular bottled water brands sold in the U.S., analyzing microplastics that were only 100 nanometers in size. They found between 110,000 and 370,000 microparticles per liter of water, 90 percent of which were nanoplastics and the rest microplastics.
Many water bottles are made with polyethylene terephthalate (PET). When the bottle is squeezed or exposed to high temperatures, the material may enter the water as the plastic fragments fall off. A recent study showed that when the cap is opened or closed repeatedly, many microplastics can enter the water.
The researchers noted that nanoplastics are smaller in size and easier to enter the human body than microplastics.
*:Technology**).