In recent years, there has been rising concern about plastic pollution, with tiny bits of plastics showing up in food, water, polar ice, and even in human blood. Their growing presence comes with potential health risks and ecosystem disruptions. Now, a new study has found that one of the most used plastic items, bottled water, contains 10 to 100 times more nanoplastics than previously estimated.
Nanoplastics are broken-down microplastics that are less than 0.1 m in diameter. The new study, by researchers from Columbia Climate School, has revealed that one litre of bottled water contains, on average, 240,000 detectable plastic fragments. Nanoplastics are so small that they can pass through the intestines and lungs, enter directly into the bloodstream and travel to organs including the heart and brain, the university’s press statement explained.
Researchers have been conducting studies to better understand the health implications of the poorly known space of nanoplastics. Plastics in bottled water became a public concern after a 2018 study identified an average of 325 particles per litre, the statement elaborated. The number has since increased as with more research focusing on it.
“People developed methods to see nanoparticles, but they didn’t know what they were looking at,” lead author, Naixin Qian said in the statement. Qian added that previous studies could provide bulk estimates of nano mass, but for the most part, could not count individual particles or distinguish which were plastics. The study was published in the Proceedings of the National Academy of Sciences.
For this study, the researchers used a technique called stimulated Raman scattering microscopy, which was co-invented by study coauthor Wei Min. This involves probing samples with two simultaneous lasers to make specific molecules resonate. The researchers focused on seven common plastics to create a data-driven algorithm to interpret the results, the statement adds.
The researchers tested three popular brands of bottled water sold in the US and identified 110,000 to 370,000 plastic fragments in each litre, 90% of which were nanoplastics and the rest were microplastics. A common one that was identified in this study was polyethylene terephthalate or PET, which is used to make many water bottles.
Notably, the seven plastic types the researchers searched for accounted for only about 10% of all the nanoparticles they found in samples. They don’t know what the rest are, the statement revealed. Talking about nanoplastics, the researchers said it’s not size that matters. "It’s the numbers, because the smaller things are, the more easily they can get inside us,” Min said.
Previous studies have also highlighted how constant use of plastics can negatively impact health. For instance, a July 2023 study by researchers at the University of Nebraska-Lincoln, found that microwaving plastic baby food containers can release massive amounts of nanoplastics and could be hazardous to health.