The average liter of bottled water contains almost a quarter million pieces of nanoplastics, a discovery made for the first time using a microscope equipped with dual lasers.
While scientists had long suspected the presence of numerous microscopic plastic particles, researchers from Columbia and Rutgers universities quantified them for the first time, shedding light on both their quantity and characteristics.
By examining five samples each from three common bottled water brands, researchers found particle levels ranging from 110,000 to 400,000 per liter, averaging around 240,000, as reported in a study published in Monday's Proceedings of the National Academy of Sciences.
These particles are smaller than a micron in size, with 25,400 microns in an inch. For perspective, a human hair is approximately 83 microns wide.
Compared to slightly larger microplastics, ranging from visible five millimeters to one micron, nanoplastics were found to be 10 to 100 times more abundant in bottled water.
The source of much of the plastic appears to be the bottle itself and the reverse osmosis membrane filter used to remove other contaminants, according to Naixin Qian, lead author of the study and a Columbia physical chemist. While the brands under study were not disclosed, Qian noted that they were commonly available brands purchased from a Walmart.
Despite the abundance of nanoplastics, researchers are still uncertain about their potential health risks.
"That's currently under review. We don't know if it's dangerous or how dangerous," said study co-author Phoebe Stapleton, a toxicologist at Rutgers in New Jersey. "We do know that they are getting into the tissues (of mammals, including people) and the current research is looking at what they're doing in the cells."
The International Bottled Water Association cautioned against drawing conclusions, citing the lack of standardized measuring methods and scientific consensus on the health impacts of nanoplastics.
Efforts to reduce bottled water consumption are already underway among the study's authors. However, outside experts emphasize the need for further research to fully understand the risks associated with nanoplastics.
Source: cbc.ca