You’ve likely heard of microplastics. Enter nanoplastics, which are even smaller and, new research shows, might just be swimming in your plastic water bottle.
A study from Columbia University has found hundreds of thousands of micro- and nanoparticles in water from plastic water bottles. The quantity is 10 to 100 times more than has been previously reported.
Considerably smaller than the diameter of a human hair, nanoplastics are of particular concern because they’re tiny enough to penetrate human cells, travel throughout the bloodstream and cross the blood-brain barrier. Nanoparticles have also been shown to cross the blood-placenta barrier: A 2022 study by Rutgers University scientists found that nanoparticles of the metal titanium dioxide crossed the placenta in rats.
Plastic use is ubiquitous across the world, and especially in the United States. One estimate found that the U.S. produced 42 million metric tons of plastic waste in 2016, or 287 pounds per person. From Tupperware to frozen dinners to water bottles, it’s a part of the great majority’s daily lives.
“Plastic has been used for 50 years, 100 years, and has been posing serious environmental issues because plastics are essentially non-degradable, or (they) take hundreds if not thousands of years to degrade,” said Wei Min, a professor of chemistry at Columbia and senior author on the paper, which was published in Proceedings of the National Academy of Science on Monday.
When plastic does break down, it does so into micro- and nanoparticles. And using a new method, the Columbia scientists found about 240,000 micro- and nanoparticles of plastic in one liter of water. (A standard plastic water bottle is about 17 ounces, or half a liter). Testing for seven common plastics, researchers found not only that those seven were present in the water of all three brands, but that the tested plastics only accounted for 10% of total particles they saw. Detected plastic polymers include three they tested for: polystyrene, polyvinyl chloride (PVC) and PET.
“Environmental scientists have been chasing these small particles for decades,” said Min. “But nanoplastics are almost impossible to study with traditional technologies.”
Min’s team, along with other Columbia researchers and Phoebe Stapleton, the senior author of the aforementioned Rutgers paper, created a new way to detect these tiny pieces of plastic.
Traditional technology involves shooting a laser at particles and measuring the energy they release. Each particle gives off an energy “signature,” telling the scientists how much of which particle exists in the sample. But nanoplastics are so small that their signatures, as measured by previous technology, were too weak to detect.
So the team added another laser, and the two lasers interacted to amplify the signal by multiple orders of magnitude, picking up on very sensitive signatures.
“This new tool opens up a new window for us,” said Beizhan Yan, an associate research professor of geochemistry at the Columbia Climate School, and one of the study authors.
When they first saw the results, they didn’t believe it, said Yan. How could all three water bottle brands result in multiple kinds of plastic ending up in the water?
“This is clearly a common and recurring issue,” said Yan. He hypothesized that it could be in part from the process of water treatment and purification, representing a systemic problem among multiple brands, which is why they chose not to disclose the three brands tested.
When Carla Ng read the study, she said the results were close to what she expected. Ng, an associate professor of civil and environmental engineering at the University of Pittsburgh, specializing in per- and polyfluoroalkyl substances — commonly known as PFAS and “forever chemicals” — said this confirms a lot of what’s already known about storing things in plastic.
“We know for additives in plastic, those chemicals can readily leach out into the water,” she said. “It is concerning to acknowledge these plastics chemically, because we know they can penetrate cells.”
But as of right now, it’s important not to jump to conclusions. Yan and Min’s study identified the existence of nanoplastics in water from plastic bottles, but their results don’t directly link to toxicity of the nanoplastics.
“There is a lot of research that needs to be done,” said Yan. “But these (new) tools are providing a great platform for us to do that.”
There’s a concept in science called a dose-response curve, which means that a drug or substance will affect the body at specific doses. When studying the health impacts of nanoplastics on the body, the same principle applies: Whether you drink from single-use plastic bottles every now and then, versus every day for 50 years, probably matters when looking at what those nanoplastics might do.
“To me, it’s more like a numbers game,” said Min. “Our job is to find out what that probability is.”
Ng, who does study the health impact from small plastic particles and chemicals, said she could see herself using data that emerges from studies like this.
“The biggest open question now is, ‘What are the implications of these findings?'” she said. “We know that the intrusion of foreign material into cells can cause inflammation. … And scientists are trying to understand the impact (of plastic exposure) over a lifetime.”
Yan and Min plan to use the new sensitive laser technology for future studies and examine other sources of water, such as tap or groundwater.
“We are doing the work right now to collect tap water from different areas of the U.S. and set up basically a baseline of nanoplastics in those waters,” said Yan.
While the public waits for more information, alternatives exist to single-use plastic. All scientists interviewed recommended stainless steel or glass reusable water bottles instead. And if it’s safe to drink your tap water, research shows it tends to have fewer microplastics than bottled water.
“Don’t heat stuff up in plastic Tupperware, please,” said Ng. And if you want to use a thicker reusable plastic bottle like a Nalgene, wash it regularly and avoid leaving it out in the sun, as UV rays can degrade plastic.
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