Bottled water packed with nanoplastics, study finds

In a trailblazing study, researchers have discovered bottled water sold in stores can contain 10 to 100 times more bits of nanoplastic than previously estimated — particles so tiny they cannot be seen under a microscope. At 1,000th the average width of a human hair, nanoplastics are so miniscule they can migrate through the tissues of the digestive tract or lungs into the bloodstream, distributing potentially harmful synthetic chemicals throughout the body and into cells, experts say.

One litre of water — the equivalent of two standard-size bottled waters — contained an average of 240,000 plastic particles from seven types of plastics, of which 90 per cent was identified as nanoplastics and the rest were microplastics, according to the study. Microplastics are polymer fragments that can range from less than 0.2 inch (5 millimeters) down to 1/25,000th of an inch (1 micrometer). Anything smaller is a nanoplastic that must be measured in billionths of a meter.

“This study, I have to say, is exceedingly impressive. The body of work that they put into this was really quite profound. … I would call it groundbreaking,” said Sherri “Sam” Mason, director of sustainability at Penn State Behrend in Erie, Pennsylvania, who was not involved in the study. The finding reinforces long-held expert advice to drink tap water from glass or stainless steel containers to reduce exposure, Mason said. “People don’t think of plastics as shedding but they do,” she said. “In almost the same way we’re constantly shedding skin cells, plastics are constantly shedding little bits that break off, such as when you open that plastic container for your store-bought salad or a cheese that’s wrapped in plastic.”

Mason is the coauthor of a 2018 study that first detected the existence of micro- and nanoplastics in 93 per cent of samples of bottled water sold by 11 different brands in nine countries. In that past study, Mason found each tainted liter of water held an average of 10 plastic particles wider than a human hair, along with 300 smaller particles. Five years ago, however, there was no way to analyze those tiny flecks or discover if there were more. “It’s not that we didn’t know nanoplastics existed. We just couldn’t analyze them”, Mason explained.

In a study published in January 2024, journal Proceedings of the National Academy of Sciences, researchers from Columbia University presented a new technology that can see, count and analyze the chemical structure of nanoparticles in bottled water.

Instead of 300 per litre, the team behind the latest study found the actual number of plastic bits in three popular brands of water sold in the United States to be in between 110,000 and 370,000, if not higher.

However, the new technology was actually able to see millions of nanoparticles in the water, which could be “inorganic nanoparticles, organic particles and some other plastic particles not among the seven major plastic types we studied,” said coauthor and environmental chemist Beizhan Yan, an associate research professor at Columbia University.