by A new study has found that the average bottle of water contains almost a quarter of a million fragments of “nanoplastics” – plastic particles so small they can gum up the machinery of human cells.
The findings published Monday in the Proceedings of the National Academy of Sciences (PNAS) open a disturbing window into a largely unmapped corner of plastic pollution — a region marked by plastics the size of viruses or vaccine particles.
“We know that microplastics are always in the environment,” co-author Beizhan Yan of Columbia University told The Hill. “They’re high up in the alpine, and down in the Marianas Trench, and a lot in New York City water as well.”
But microplastics are relatively large and easy to measure, he said – measurable in millionths of a meter, they can be seen using technology like scanning electron microscopes.
The team was concerned about nanoplastics, which are particles thousands of times smaller – measurable in billions of metres. These small amounts can pose a greater danger, Yan said, “because the smaller the size of the particles, the easier it is to get into the human body and then cross different barriers.”
The tiny compounds, Yan said, “can cross into the blood, and then they can cross the various barriers to enter the cells,” affecting the organs – cellular organs – “and causing them to malfunction .”
Microplastics and nanoplastics have been found to have a wide range of dangerous effects on a huge range of key systems in the human body, as found in a December article in The Lancet.
That survey of recent research found that tiny plastics can disrupt the chemistry of the human body – affecting the communities of microbes in our guts that help us digest food.
Micro- and nanoplastics can lead to “oxidative stress, inflammation, immune dysfunction, altered biochemical and energy metabolism, impaired cell proliferation, disruption of microbial metabolic pathways, abnormal organ development, and carcinogenicity,” wrote the Lancet authors. .
So if these potentially dangerous compounds are found in bottled water, is it safe to drink?
Knowing about the potential risks of nanoplastics is only half the answer: scientists also need to know what plastic polymers people are ingesting, and in what quantities, to determine how dangerous exposure can be.
That’s where the PNAS study comes in. Using an innovative new laser imaging method, scientists have been able to identify plastics of much smaller sizes than ever before, including some of the most worrying.
By running water from three common brands through an extremely fine filter, they were able to capture – and then identify – particles measurable on the scale of billionths of a metre.
Those plastics, however, made up only 10 percent of the total nanoparticles found by the scientists. They also found pieces of microscopic clay, metal and carbon black from fires that had not yet been identified – as well as plastics so degraded they could not be picked up by imaging technology.
The presence of objects of this size can affect the body, because even if they are chemically inert, they are small enough to enter cells and affect them, like sand in an engine.
But the chemical structure of plastics is of particular concern, the scientists said.
Because plastics are so similar to the chemistry of living creatures — petrochemicals, after all, come from the ancient remains of long-dead organisms — they can mimic or disrupt key biological functions by mimicking the structure of the chemical messengers that help drive a wide range. body functions.
The scientists found a wide variety of plastics in the bottles, but five types stood out – starting with polyethylene terephthalate (PET).
Since the structure of the bottles themselves is PET, that decision was not much of a surprise. There was also little concern, since PET is generally thought to be safe, even though PET compounds can contain the toxic catalyst antimony.
But it was also found that the water in the bottles contained a wide range of potentially dangerous nanoplastics that are not found in the bottles themselves – pointing to unknown sources of environmental contamination.
Scientists have identified compounds such as nylon, which break down into toxic monomers as it degrades; polystyrene (or Styrofoam, commonly found in foam containers), which can break down into the suspected carcinogen styrene; and polyvinyl chloride (PVC), which may contain harmful additives such as lead or phthalates, and which have been linked to disturbances in the nervous or endocrine systems.
In what the researchers called an ironic discovery, they also found plastic compounds in the water to match the primary material in reverse osmosis filters – suggesting that the plastics had leached into the water through the filtration process, co-author Naixin Qian of Columbia University told The Hill.
But the more dangerous particles such as PVC and polystyrene appeared to get into the plastic bottles with the “water source” that filled them, Qian said.
One possibility for how these got into that water: According to the Environmental Protection Agency, plastics plants emit aerosolized plastic gases that can enter the environment — getting into the air, and thus rain and water.
Regardless of the source of the nanoplastics, however, the Columbia team was particularly concerned about the health risks they pose – especially to the young and very old.
These particles are small enough to cross the blood-brain barrier, which means they can lead to neurological degeneration, especially in the elderly, where the barrier is “looser,” Yan said.
Exposure to microplastics and nanoplastics could lead to cell damage in the nervous system, leading to an increased risk of nervous system disorders and changes in behavior — and nanoplastics are more harmful than microplastics.
Nanoplastics are also small enough to cross the placenta into the general sheltered environment of the womb, and effects on a developing fetus are unknown.
For example, nanoplastics can enter the umbilical veins that draw blood and waste products back from an embryo, interfering with cell processes that help dispose of cellular debris. They can also cause significant damage to an embryonic kidney and reproductive cells, as well as impairing the normal growth of the fetal heart.
The developing fetal nervous system is also very susceptible to damage from environmental pollutants, and nanoplastics could make it harder for the cells in fetal brain tissue to stay alive.
Since these plastics enter the body through drinking water – and therefore, the digestive system – that may be the site of the most immediate effects. Scientists discovered that PET disrupts key microbial communities in the human gut, encouraging the growth of harmful bacteria and inhibiting the beneficial ones.
And studies in mice have found that microplastics and nanoplastics cause cell death in the lining of the intestine and increase inflammation in the gut.
If nanoplastics are able to pass from the digestive system into the bloodstream, the effects could be much more far-reaching – starting with heart disease.
There is strong evidence that this can happen. A 2021 study found that when rats were given water embedded with polystyrene, or Styrofoam, nanoparticles, those particles began to accumulate in their hearts – causing the heart to swell with collagen, which made it harder for him to hit and, in the end, an untimely death among them. heart cells.
And tests in a Petri dish found that nanoparticles could destroy human red blood cells, although they were unable to replicate these results inside actual blood.
But as dire as these lab results are, the risks associated with nanoplastics are still a matter of concern. Although such particles can be highly toxic to cells at high doses, it is not clear what happens at the levels that normal people are exposed to.
That gap in our knowledge stems from a gap in technology – with no reliable way to identify nanoparticles in the environment, scientists have been unable to accurately calculate how many particles cells will be exposed to in order to test the effects of the exposure.
Columbia’s findings take an important step toward closing that gap.
So, perhaps more significant than the results themselves — which are alarming, but difficult to put into context — is the way the Columbia University team discovered them: through a new method that the scientists say will allow them to identify specific nanoplastics in soils, air and human tissue.
That method is called Raman scattering – a method co-developed by study co-author Wei Min that hits an unknown plastic particle with a laser beam and decodes the frequency of the light that bounces back to tell what plastic polymer is inside.
Compounds like PVC, PET and polystyrene “are made of different chemical bonds,” said Min. “Those different chemical bonds have different, fundamentally different energies. And we can use a laser to interrogate that energy and detect the interaction between the laser and that part of the chemical bonds.”
That allows researchers to “distinguish between different chemical bonds, and therefore different types of polymers,” Min said.
But Qian cautioned that the team still doesn’t know enough to say, for example, how the nanoplastic levels in bottles compare to tap water levels across the nation. (The team hopes to begin providing results for the nation’s tap water supply within the next two years.)
Qian said the baton is now passed to toxicologists to determine how the levels the team found in bottled water translate to actual health effects.
“We’ve only done the first step in terms of quantifying the exposure: how much [nanoplastics] we are in the water bottle [are] really exposed every day,” said Qian.
“Once you have the exact exposure then you can do more research on the consequences of toxicity,” she said.
— Updated at 4:55pm
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