Jan. 9, 2024 – Each liter of water in a plastic bottle may contain more than 100,000 microscopic pieces of plastic, new research shows. The important finding suggests that the amount of plastic consumed by many people simply through drinking a bottle of water is 10 times greater than thought before.
The tiny plastic bits that slough off bottles are called microplastics and nanoplastics. They have raised concerns about potential health impacts, which have been difficult to study partly because the pieces of plastic are so small that they can be difficult to detect.
The Columbia University team developed a new imaging technique that has “unprecedented sensitivity and specificity” for analysis of nanoplastics, according to their paper, which was published Monday in the journal Proceedings of the National Academy of Sciences.
“Previously this was just a dark area, uncharted. Toxicity studies were just guessing what’s in there,” researcher Beizhan Yan, PhD an environmental chemist at Columbia Climate School’s Lamont-Doherty Earth Observatory, said in a statement. “This opens a window where we can look into a world that was not exposed to us before.”
The new, laser-based technique to detect microplastic and nanoplastic particles was used to analyze three popular brands of bottled water sold in the U.S. (The researchers did not publish the names of the brands.) Each liter of water from the bottles was found to contain between 110,000 and 370,000 plastic fragments, about 90% of which were nanoplastics and the rest were the larger microplastics.
The researchers looked for seven common types of plastics, and among the most common were polystyrene, polyvinyl chloride, polymethyl methacrylate, and polyethylene terephthalate or PET, the latter of which is what the bottles themselves are made of. Another plastic found in high amounts was a type of nylon called polyamide, according a summary of the research published by Columbia University, which noted that the polyamide found may come from plastic filters that the water goes through before bottling.
The seven types of plastics the researchers looked for accounted for just 10% of the nanoparticles detected in the bottled water, and the researchers have not determined what the other 90% are made of.
“If they are all nanoplastics, that means they could number in the tens of millions per liter,” according to the Columbia University summary of the paper, which noted that "they could be almost anything.”
The research team plans to analyze tap water next.
