The average liter of bottled water has nearly a quarter million invisible pieces of ever so tiny nanoplastics, detected and categorized for the first time by a microscope using dual lasers.
Scientists long figured there were lots of these microscopic plastic pieces, but until researchers at Columbia and Rutgers universities did their calculations, they never knew how many or what kind. Looking at five samples – each of three common bottled water brands, researchers found particle levels ranged from 110,000 to 400,000 per liter, averaging at around 240,000, according to a new study in the Proceedings of the National Academy of Sciences on Monday.
Much of the plastic seems to be coming from the bottle itself and the reverse osmosis membrane filter used to keep out other contaminants, said study lead author Naixin Qian, a Columbia physical chemist. She wouldn't reveal the three brands because researchers want more samples before they single out a brand and want to study more brands. Still, she said they were common and bought at a WalMart.
Naixin Qian, a Columbia physical chemist, zooms in on an image generated from a microscope scan, with nanoplastics, microscopic plastic pieces, appearing as bright red dots in New York, the U.S., January 8, 2024. /AP
"If people are concerned about nanoplastics in bottled water, it's reasonable to consider alternatives like tap water," Beizhan Yan, an associate research professor at Columbia University and a co-author of the paper, told AFP.
"We do not advise against drinking bottled water when necessary, as the risk of dehydration can outweigh the potential impacts of nanoplastics exposure," he added.
There has been rising global attention in recent years on microplastics, which break off from bigger sources of plastic and are now found everywhere from the polar ice caps to mountain peaks, rippling through ecosystems and finding their way into drinking water and food.
While microplastics are anything under 5 millimeters, nanoplastics are defined as particles below 1 micrometer, or a billionth of a meter - so small they can pass through the digestive system and lungs, entering the bloodstream directly and from there to organs, including the brain and heart. They can also cross the placenta into the bodies of unborn babies.
Bottled water. /CFP
There is limited research on their impacts on ecosystems and human health, though some early lab studies have linked them to toxic effects, including reproductive abnormalities and gastric issues.
To study nanoparticles in bottled water, the team used a technique called Stimulated Raman Scattering (SRS) microscopy, which was recently invented by one of the paper's co-authors, and works by probing samples with two lasers tuned to make specific molecules resonate, revealing what they are to a computer algorithm.
Next, the team hopes to probe tap water, which has also been found to contain microplastics, though at far lower levels.
(With input from AP and AFP)