January’s Proceedings of the National Academy of Sciences carried results of a Columbia University-Rutgers University study that found roughly 240,000 detectable plastic fragments – both microplastics and nanoplastics – in a typical liter of bottled water. That’s 10 to 100 times more than previously estimated.
How dangerous they are and who’s responsible for controlling them remain at issue.
Microplastics have already been found in people's lungs, their excrement, their blood and in placentas, among other places. A 2018 study found an average of 325 pieces of microplastics in a liter of bottled water, the National Academy report said.
Nanoplastics – the study calls them “the spawn of microplastics that have broken down even further” – could be even more dangerous than microplastics because of their size and they can be misidentified as a natural component of a cell.
The researchers tested three brands of bottled water – they did not identify the brands – using a technology involving two lasers called stimulated Raman scattering (SRS) microscopy to detect the particles and used machine learning to identify them.
They searched for seven common types of plastic. No surprise that polyethylene terephthalate (PET) was found, considering it’s the material used to create water bottles. However, PET was outnumbered by polyamide, a type of nylon. Ironically, according to one of the researchers, that probably comes from plastic filters used to purify the water before it is bottled. Other common plastics the researchers found were polystyrene, polyvinyl chloride and polymethyl methacrylate, all used in various industrial processes.
The International Bottled Water Assn. said it had “very limited notice and time to review this new study closely and therefore, we cannot provide a detailed response at this time.” But the group noted that the analysis method used was new “and needs to be fully reviewed by the scientific community.”
After reviewing this and other studies, the World Health Organization (WHO) concluded that no adverse health effects could be drawn from dietary exposure to nano- and microplastic particles less than 10 microns due to minimal scientific research, although WHO recommended more research to be conducted.
The same team plans to look at tap water, which also has been shown to contain microplastics, although far less than in bottled water.