by Almost a quarter of a million invisible pieces of nanoplastics that are as small as an average liter of bottled water have been detected and categorized for the first time by a microscope using dual lasers.
Scientists have long realized that there were many of these microscopic pieces of plastic, but until researchers at Columbia and Rutgers universities did their calculations they didn’t know how many or what kind. Looking at five samples each of three common brands of bottled water, researchers found particle levels between 110,000 and 400,000 per liter, averaging about 240,000 according to a study in Monday’s Proceedings of the National Academy of Sciences.
These are particles that are less than a micron in size. There are 25,400 microns – also called a micrometer because it is one millionth of a meter – in an inch. A human hair is about 83 microns wide.
Previous studies have looked at slightly larger microplastics that range from the visible 5 millimeters, less than a quarter of an inch, to just a micron. About 10 to 100 times more nanoplastics than microplastics were found in bottled water, the study found.
Much of the plastic appears to be coming from the bottle itself and the reverse osmosis membrane filter used to keep out other contaminants, said study lead author Naixin Qian, a Columbia physical chemist. She would not reveal the three brands because researchers need more samples before naming a brand and want to study more brands. Still, she said they were popular and bought at WalMart.
Researchers still can’t answer the big question: Are those pieces of nanoplastic harmful to health?
“That is currently being reviewed. We don’t know if it’s dangerous or how dangerous it is,” said study co-author Phoebe Stapleton, a toxicologist at Rutgers. “We know they’re getting into tissues (including mammals, humans) … and the current research is looking at what they’re doing in the cells.”
The International Bottled Water Association said in a statement: “There is currently a lack of standardized (measurement) methods and no scientific consensus on the potential health effects of nano- and microplastic particles. Therefore, reports in the media about these particles in drinking water do nothing more than unnecessarily alarm consumers.”
The American Chemistry Council, which represents plastics manufacturers, declined to immediately comment.
The world “is drowning under the weight of plastic pollution, with more than 430 million tons of plastic being produced annually” and microplastics found in the world’s oceans, food and drinking water with some coming from clothing and cigarette filters, of according to the United Nations Environmental Program of Nations. Efforts for a global plastics treaty continue after talks stalled in November.
All four co-authors interviewed said they were cutting back on their bottled water use after doing the study.
Wei Min, the Columbia physical chemist who pioneered dual-laser microscope technology, said he cut his bottled water use in half. Stapleton said she now relies more on filtered water at home in New Jersey.
But study co-author Beizhan Yan, a Columbia environmental chemist who has increased his use of tap water, pointed out that filters themselves can become a problem by introducing plastics.
“There’s just no winning,” Stapleton said.
Outside experts, who praised the study, agreed that there is general unease about the dangers of fine plastic particles, but it is too early to say for sure.
“The danger of the plastics themselves is still an unanswered question. For me, it’s the additives that worry me the most,” said professor of medicine and director of the comparative oncology group Jason Somarelli, who was not part of the research. “We and others have shown that these nanoplastics can be internalized into cells and we know that nanoplastics carry all kinds of chemical additives that can cause cell stress, DNA damage and alter cell metabolism or function.”
Somarelli said there are more than 100 “known cancer-causing chemicals in these plastics of his that have not yet been published.”
What’s worrying, said University of Toronto evolutionary biologist Zoie Diana, is that “small particles can appear in different organs and can cross membranes they’re not supposed to cross, like the blood barrier -brain.”
Diana, who was not part of the study, said that the researchers use a new tool that makes this an exciting development in the study of plastics in the environment and the body.
About 15 years ago, Min invented dual laser microscope technology that identifies specific compounds by their chemical properties and how they resonate when exposed to the lasers. Yan and Qian talked to him about using that technique to find and identify plastics that were too small for researchers using established methods.
Kara Lavender Law, an oceanographer at the Sea Education Association, said the work “could be an important advance in the detection of nanoplastics” but said she would like to see other analytical chemists replicate the technique and the results.
Denise Hardesty, an Australian government oceanographer who studies plastic waste, said context is needed. The total weight of the nanoplastics found is “roughly equivalent to the weight of one penny the size of two Olympic swimming pools.”
Hardesty is less concerned than others about nanoplastics in bottled water, noting “I’m privileged to live where I have access to ‘clean’ tap water and don’t have to buy drinking water in single-use containers .”
Yan said he is starting to study other municipal water supplies in Boston, St. Louis, Los Angeles and other places to see how much plastic is in their tap water. Previous studies looking for microplastics and some early tests indicate that tap water may contain less nanoplastics than bottled water.
Even with nothing known about human health, Yan said he has one suggestion for people who are concerned: Use reusable bottles instead of single-use plastics.
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