Tiny particles of plastic known as microplastics, which break down from larger pieces of plastic, are being consumed by humans from drinking water to food. A new study published in the Proceedings of the National Academy of Sciences journal explored the world of nanoplastics and their presence in bottled drinking water.
The focus of the research was plastic bottled drinking water, which was shown to contain tens of thousands of identifiable fragments in each container.
“Previously this was just a dark area, uncharted,” Beizhan Yan, study co-author and an environmental chemist at Columbia Climate School’s Lamont-Doherty Earth Observatory, said. “Toxicity studies were just guessing what’s in there. This opens a window where we can look into a world that was not exposed to us before.”
The study tested three popular brands of bottled water sold in the United States by using a technique called stimulated Raman scattering microscopy, which was co-invented by the study’s co-author, Wei Min, a Columbia biophysicist. The technique probes samples with “two simultaneous lasers that are tuned to make specific molecules resonate,” according to a press release. The study targeted seven common plastics and created a data-driven algorithm to interpret the results.
“It is one thing to detect, but another to know what you are detecting,” said Min.
The researchers analyzed plastic particles as small as “100 nanometers in size and spotted 110,000 to 370,000 plastic fragment in each liter, 90 percent of which were nanoplastics; the rest microplastics,” according to a press release. Of the seven specific plastics they researched, polyethylene terephthalate or PET and polyamide, a type of nylon, were the most common found in the bottled drinking water.
PET is the type of plastic many water bottles are made of, while polyamide “probably comes from plastic filters used to supposedly purify the water before it is bottled,” Yan said. Other plastics found in the bottled drinking water included polystyrene, polyvinyl chloride and polymethyl methacrylate.
But the seven plastic types the researchers studied only accounted for 10 percent of all the nanoparticles they found in the samples—the rest were unknown. According to researchers, if the rest are nanoplastics, that means plastics could number in the tens of millions per liter in a bottle of drinming water.
“The common existence of natural organic matter certainly requires prudent distinguishment,” the authors said.
The study also charted their shapes—qualities that could be valuable in biomedical research, according to the press release.
“There is a huge world of nanoplastics to be studied,” Min, said. “…it’s not size that matters. It’s the numbers, because the smaller things are, the more easily they can get inside us.”
The researchers said they will continue their research going beyond bottled water to study tap water and even snow. They are working with environmental health experts to determine the developmental and neurologic effects of nanoplastics that have been inhibited human tissues.
“Plastics are now omnipresent in our daily lives,” authors said.