Scientists from Columbia and Rutgers universities have discovered that the average liter of bottled water contains nearly a quarter million invisible nanoplastics, marking the first time these microscopic particles have been detected and categorized. The study, published in the Proceedings of the National Academy of Sciences, analyzed five samples from three common bottled water brands and found particle levels ranging from 110,000 to 400,000 per liter, averaging at around 240,000.

These nanoplastics, which are less than a micron in size, far outnumber slightly larger microplastics previously studied. In fact, the study revealed that there are 10 to 100 times more nanoplastics in bottled water compared to microplastics. The primary sources of these particles appear to be the bottles themselves and the reverse osmosis membrane filters that are used to remove other contaminants.

While the presence of nanoplastics in drinking water raises concerns, researchers have yet to determine if these particles pose any health risk. The study's lead author, Naixin Qian, a physical chemist at Columbia, explained that the potential dangers of nanoplastics are currently under review. However, the findings are concerning because these particles have been observed to accumulate in the tissues of mammals, including humans.

The International Bottled Water Association released a statement acknowledging the lack of standardized measuring methods and scientific consensus on the health impacts of nanoplastics, dismissing media reports as unnecessarily alarming consumers. The American Chemistry Council, representing plastics manufacturers, declined to comment.

According to the United Nations Environment Programme, the world produces over 430 million tonnes of plastic annually, contributing to the global pollution crisis. Microplastics have been found not only in oceans but also in food, drinking water, clothing, and cigarette filters. Efforts for a global plastics treaty continue, with talks ongoing since November.

In response to their own study, all four co-authors have pledged to reduce their reliance on bottled water. Wei Min, the Columbia physical chemist who developed the dual laser microscope technology used in the study, has reduced his bottled water use by half. Phoebe Stapleton, a toxicologist at Rutgers, now relies more on filtered water at home. Study co-author Beizhan Yan, an environmental chemist at Columbia, has increased his tap water usage, but points out that filters themselves can introduce plastics as a potential problem.

While experts have praised the study, emphasizing the need for further research, they agree that the presence of nanoplastics raises concerns about the potential perils of these fine plastic particles. However, it is still too early to definitively determine the risks they pose to human health.