Bottled water contains 100 times more nanoplastic than previously thought

Recent research has uncovered that the average litre of bottled water contains nearly 250,000 microplastics and minute, imperceptible nanoplastics.

This discovery, identified for the first time using a microscope equipped with dual lasers, has shed light on the extent and nature of these microscopic plastic particles.

While scientists had speculated on the existence of these minute plastic fragments, it wasn’t until researchers from US universities Columbia and Rutgers conducted their calculations that the quantity and types became known.

Analysing five samples from each of three popular bottled water brands, the researchers found particle levels ranging from 110,000 to 400,000 per litre, with an average of around 240,000, according to a study published in Monday’s Proceedings of the National Academy of Sciences.

Nanoplastics, defined as particles smaller than a micron, were the focus of this research. In an inch, there are 25,400 microns (also known as micrometres), and a human hair is approximately 83 microns wide. Unlike previous studies that investigated slightly larger microplastics, ranging from visible 5 millimetres to one micron, this study discovered 10 to 100 times more nanoplastics than microplastics in bottled water.

The plastic appears to originate primarily from the bottle itself and the reverse osmosis membrane filter used to exclude other contaminants, explained study lead author Naixin Qian, a Columbia physical chemist. While the three common brands studied were not disclosed, Qian mentioned they were commonplace and purchased from US supermarket Walmart.

Regarding the potential health impact of nanoplastic pieces, researchers remain uncertain. Study co-author Phoebe Stapleton, a toxicologist at Rutgers, stated, “That’s currently under review. We don’t know if it’s dangerous or how dangerous. 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.”

In response to the findings, the International Bottled Water Association highlighted the lack of standardized measuring methods and the absence of scientific consensus on the health impacts of nano- and microplastic particles. The American Chemistry Council, representing plastics manufacturers, declined immediate comment.

With over 430 million tonnes of plastic produced annually, the world faces a crisis of plastic pollution, as microplastics are detected in oceans, food, and drinking water. Efforts towards a global plastics treaty continue following stalled talks in November, according to the United Nations Environment Programme.

All four co-authors of the study revealed that they are reducing their consumption of bottled water in light of their findings. Wei Min, the Columbia physical chemist who developed the dual laser microscope technology, stated that he has cut his bottled water use by half. Stapleton reported relying more on filtered water at her New Jersey home. However, co-author Beizhan Yan, a Columbia environmental chemist, cautioned about filters introducing plastics.

“There’s just no win,” remarked Stapleton, echoing the sentiment of outside experts who, while praising the study, indicated a general unease about the dangers of fine plastic particles, stressing that it is too early to draw definitive conclusions.