Researchers testing 259 individual bottles of water from 11 different brands sold in 9 countries found that 93% of the bottles showed signs of microplastic contamination.
Researchers were looking for a geographically diverse collection of bottles from leading brands like Aquafina, Dasani, Evian, Nestle Pure Life, and San Pellegrino.
Only 17 bottles of the 259 sampled showed no microplastic contamination. 65% of the plastic particles found in the contaminated samples were "fragments" of plastic, and included the plastic used to make some of the bottle caps.
"I think it is coming through the process of bottling the water," researcher Sherri Mason of the State University of New York at Fredonia told USA Today. "I think that most of the plastic that we are seeing is coming from the bottle itself, it is coming from the cap, it is coming from the industrial process of bottling the water."
Researchers admit that it is unclear what effect microplastics have on the human body.