Bottled water’s reputation for purity took a hit in Columbus, where Ohio State University researchers found it contained about three times as many nanoplastic particles as treated tap water. The team traced most of that gap to the bottles and packaging themselves, then put the two types of drinking water head to head using a lab setup built to catch the tiniest bits of plastic.
To keep the comparison fair, the researchers pulled one sample from each of six bottled brands and matched them against treated water taken from four conventional plants near Lake Erie, creating a like-for-like test of what most people actually drink.
How scientists measured the tiny plastics
The study, published in Science of The Total Environment, paired scanning electron microscopy with optical photothermal infrared spectroscopy (OPTIR). That combo let the team spot and identify plastic particles down to about 300 nanometers across, far below what standard methods usually pick up.
More than half of the particles the team detected in both bottled and treated tap water were nanoplastics smaller than 1 micrometer. Bottled samples carried clearly higher counts in this sub-micron range, while the overall mass of plastic was not significantly different between bottled and treated water. In other words, the total weight of plastic was similar, but bottled water had many more and smaller pieces.
Which waters were tested
Researchers analyzed a single sample from each of six bottled brands and duplicate samples from four drinking water treatment plants. The bottled samples were dominated by PET, polyamide (nylon), polyethylene and even tiny rubber fragments. Treated tap water, by contrast, contained relatively more polyamides and polyesters, according to Cleveland.com…