A new study has found that the average water bottle contains almost a quarter of a million fragments of ‘nanoplastics’ – plastic particles so small they could potentially eat away at the machinery of human cells.
The findings published Monday in the Proceedings of the National Academy of Sciences (PNAS) open a troubling window into a largely uncharted corner of plastic pollution — an area characterized by plastics the size of approximately viruses or vaccine particles.
“We know that microplastics always exist in the environment,” co-author Beizhan Yan of Columbia University told The Hill. “They are high up in the Alps, and down in the Marianas Trench, and also quite a lot in the waters of New York City.”
But microplastics are relatively large and easy to measure, he said. They are measurable in millionths of a meter and can be viewed using technology such as a scanning electron microscope.
The team was concerned about nanoplastics, particles that are thousands of times smaller – measurable in billionths of a meter. These smaller sizes can translate into a greater danger, Yan said, “because the smaller the particle size, the more easily they enter the human body and then cross various barriers.”
The small compounds, Yan added, “can enter the blood and then cross the various barriers to get into the cells,” disrupting the organelles – cellular organs – “and causing them to malfunction.”
Both micro- and nanoplastics appear to have a wide range of dangerous effects on a dizzying array of key systems in the human body, as shown in a December article in The Lancet.
That review of recent research found that tiny plastics can disrupt the chemistry of the human body – which could impact both the communities of microbes in our gut that help us digest food.
Micro- and nanoplastics can lead to “oxidative stress, inflammation, immune dysfunction, altered biochemical and energy metabolism, reduced cell proliferation, disrupted microbial metabolic pathways, abnormal organ development and carcinogenicity,” the Lancet authors wrote.
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 puzzle: Scientists also need to know which plastic polymers people are actually ingesting, and in what amounts, to determine how dangerous exposure might be.
That’s where the PNAS research comes into play. Using an innovative new method of laser imaging, the scientists were able to identify plastics much smaller than ever before, including some that may be of concern.
By running water from three commonly used brands through an extremely fine-grained filter, they were able to capture particles measurable on a scale of billionths of a meter – and then identify them.
However, these plastics made up only 10 percent of the total nanoparticles the scientists found. They also found unidentified pieces of microscopic clay, metals and the black carbon from fires – as well as plastic that had broken down so much that imaging technology couldn’t pick them up.
The mere presence of objects of this size is potentially disruptive to the body, because even if they are chemically inert, they are small enough to enter and disrupt cells, much 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 things—petrochemicals come from the ancient remains of long-dead organisms, after all—they can mimic or disrupt important biological functions by imitating the structure of the chemical messengers that help a wide range of chemical messengers drive. of body functions.
The scientists found a wide range of plastics in the bottles, but five types dominated – starting with polyethylene terephthalate (PET).
Since PET forms the structure of the bottles themselves, this finding was no surprise. It also raised little concern because PET is believed to be generally safe, although PET compounds may contain the toxic catalyst antimony.
But the water in the bottles was also found to contain a wide range of potentially dangerous nanoplastics not found in the bottles themselves – pointing to unknown sources of environmental contamination.
The scientists identified compounds such as nylon, which breaks down into toxic monomers during degradation; polystyrene (or Styrofoam, often found in foam containers), which can break down into the suspected carcinogenic styrene; and polyvinyl chloride (PVC), which may contain harmful additives such as lead or phthalates, and has been linked to disturbances of the nervous or endocrine systems.
In what the researchers called an ironic finding, they also found plastic compounds in the water that matched the primary material in reverse osmosis filters — suggesting the plastics had leached into the water through the filtration process, says co-author Naixin Qian of Columbia University told The Hill.
But the more dangerous particles such as PVC and polystyrene appeared to have entered the plastic bottles with the “spring water” they were filled with, Qian said.
One possibility for how they got into that water: According to the Environmental Protection Agency, plastic factories emit plastic gases that can escape into the environment—and thus end up in the air, and thus in rain and water.
Regardless of the source of the nanoplastics, however, the Columbia team was primarily concerned about the health risks they pose – especially for the very young and very old.
These particles are small enough to cross the blood-brain barrier, meaning they can lead to neural degeneration, especially in the elderly, where the barrier is “looser,” Yan said.
Exposure to micro- and nanoplastics can lead to cell damage in the nervous system, leading to an increased risk of nervous system disorders and behavioral changes – with nanoplastics being more harmful than microplastics.
Nanoplastics are also small enough to cross the placenta and enter the usually sheltered environment of the uterus, with unknown effects on a developing fetus.
For example, nanoplastics can get into the umbilical veins that withdraw blood and waste products from an embryo, disrupting the cell processes that help remove cell debris. They can also cause significant damage to the embryonic kidney and reproductive cells, and impede the normal growth of the fetal heart.
The developing nervous system of the fetus is also highly sensitive to damage from environmental pollutants, and nanoplastics can make it harder for the cells in fetal brain tissue to stay alive.
Given that these plastics enter the body through drinking water – and therefore through the digestive system – this could be the site of the most direct consequences. Scientists have found that PET disrupts key microbial communities in the human gut, encouraging the growth of harmful bacteria and suppressing beneficial bacteria.
And studies in mice have shown that micro- and nanoplastics lead to cell death in the intestinal mucosa and increase inflammation in the intestines.
If nanoplastics can enter the bloodstream from the digestive system, the consequences could be much more widespread, starting with heart disease.
There is strong evidence that this can happen. A 2021 study found that when rats were given water with polystyrene, or Styrofoam, nanoparticles embedded in them, these particles began to build up in their hearts, causing the heart to swell with collagen, making it harder to beat and ultimately led to premature death among the rats. heart cells.
And tests in a petri dish showed that nanoparticles could destroy human red blood cells, although they could not reproduce these findings in real blood.
But as disturbing as these laboratory results are, the risks of nanoplastics remain a matter of conjecture at this time. While such particles can be highly toxic to cells at high doses, it is much less clear what happens at the levels that ordinary people are actually exposed to.
That gap in our knowledge is the result of a gap in technology: Without any reliable way to identify nanoparticles in the environment, scientists have been unable to accurately calculate how many particles to expose cells to to test the impact of exposure .
Columbia’s findings are an important step toward closing that gap.
As such, perhaps more important than the findings themselves – which are alarming but difficult to put into context – was the way the Columbia University team discovered them: via a new method that the scientists say will allow them to identify specific nanoplastics in soil, air and human tissue.
That method is called Raman scattering – a method co-developed by 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 determine which plastic polymer is inside.
Compounds such as PVC, PET and polystyrene are all “made of different chemical bonds,” Min said. “Those different chemical bonds have different, essentially intrinsic energy. And we can use laser to interrogate that energy and detect the interaction between the laser and that part of the chemical bonds.”
That allows researchers to “distinguish different chemical bonds, and therefore different types of polymers,” Min added.
But Qian cautioned that the team still doesn’t have enough information to say, for example, how levels of nanoplastics in bottles compare to levels in tap water across the country. (The team expects to start rolling out results for the national tap water supply within the next two years.)
Qian said the baton will now be passed to toxicologists to determine how the levels the team found in bottled water translate into actual health impacts.
“We’ve only done the first step in terms of quantifying exposure: how much [nanoplastics] there are in the bottle of water we have [are] basically exposed every day,” Qian said.
“Once you have the precise exposure, you can actually do more research into the effects of the toxicity,” she said.
— Updated at 4:55 PM
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