by A new study has found that the average water bottle contains almost a quarter of a million “nanoplastic” fragments – plastic particles so small they can potentially jam 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 about 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 Alps, in the Mariana Trench, and also in quite a few waters around New York City.”
But microplastics are comparatively large and easy to measure, he said: They can be measured in millionths of a meter and can be observed using technology such as a scanning electron microscope.
The team was concerned about nanoplastics, which are particles thousands of times smaller, measurable in billionths of a meter. These smaller sizes can translate into greater danger, Yan said, “because the smaller the size of the particles, the easier it is for them to enter human bodies and then cross different barriers.”
The tiny compounds, Yan added, “can cross into the blood and then cross the different barriers to reach the cells,” interfering with the organelles (cellular organs) “and causing them to malfunction.”
Both microplastics and nanoplastics have been found to have a wide range of dangerous impacts on a staggering array of key human body systems, as a December paper in The Lancet found.
That recent research study found that tiny plastics can interfere with human body chemistry, causing impacts both on and from the communities of microbes in our gut that help us digest food.
Micro- and nanoplastics can cause “oxidative stress, inflammation, immune dysfunction, alteration of biochemical and energy metabolism, alteration of cell proliferation, alteration of microbial metabolic pathways, abnormal organ development, and carcinogenicity,” the Lancet authors wrote.
So if these possibly dangerous compounds are found in bottled water, is it safe to drink?
Knowing 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 quantities, to determine how dangerous exposure may be.
That’s where the PNAS study comes into play. Using an innovative new laser imaging method, scientists were able to identify plastics of much smaller sizes than ever before, including several of potential concern.
By passing water from three common brands through an extremely fine-grained filter, they were able to trap measurable particles on a scale of billionths of a meter and then identify them.
However, those plastics made up only 10 percent of the total nanoparticles the scientists found. They also found as-yet-unidentified fragments of microscopic clays, metals and black carbon from the fires, as well as plastics so degraded that imaging technology could not detect them.
The mere presence of objects this size is potentially harmful to the body, because even if they are chemically inert, they are small enough to penetrate cells and disrupt them, like sand in an engine.
But the chemical structure of plastics makes them of particular concern, scientists said.
Because plastics are so similar to the chemistry of living things (after all, petrochemicals come from the ancient waste of long-dead organisms), they can mimic or alter key biological functions by mimicking the structure of the chemical messengers that They help boost a wide range of bodily functions.
Scientists found a wide range of plastics in the bottles, but five types predominated, starting with polyethylene terephthalate (PET).
Since PET makes up the structure of the bottles themselves, that finding was not a surprise. It also raised little concern, as PET is believed to be generally safe, although PET compounds may contain antimony, a toxic catalyst.
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 pollution.
Scientists identified compounds such as nylon, which breaks down into toxic monomers as it degrades; polystyrene (or styrofoam, commonly found in foam containers), which can break down into styrene, the suspected carcinogen; and polyvinyl chloride (PVC), which may contain harmful additives such as lead or phthalates, and which has been linked to alterations in 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 of the reverse osmosis filters, suggesting that the plastics had leached into the water through the same filtration process, co-author Naixin Qian of Columbia University told The Hill.
But more dangerous particles such as PVC and polystyrene appeared to have entered the plastic bottles with the “water fountain” that filled them, Qian said.
One possibility for how they could have gotten into the water: According to the Environmental Protection Agency, plastic plants emit aerosolized plastic gases that can reach the environment, entering the air and, therefore, rain and water.
However, regardless of the source of the nanoplastics, the Columbia team was particularly concerned about the health risks they pose, especially to the very young and very old.
These particles are small enough to cross the blood-brain barrier, meaning they can cause neuronal degeneration, especially in older people, in whom the barrier is “laxer,” Yan said.
Exposure to micro- and nanoplastics can cause cellular damage to the nervous system, increasing the risk of nervous system disorders and behavioral changes; Nanoplastics are more harmful than microplastics.
Nanoplastics are also small enough to cross the placenta into the generally protected environment of the uterus, with unknown effects on the developing fetus.
For example, nanoplastics can enter the umbilical veins that draw blood and waste products from an embryo, interfering with cellular processes that help remove cellular waste. They can also cause significant damage to embryonic kidneys and reproductive cells, in addition to impairing the normal growth of the fetal heart.
The developing fetal nervous system is also very susceptible to damage from environmental pollutants, and nanoplastics can make it difficult for fetal brain tissue cells to stay alive.
Since these plastics enter the body through drinking water (and therefore the digestive system), that could be the site of the most immediate impacts. Scientists have discovered that PET interferes with key microbial communities in the human intestine, encouraging the growth of harmful bacteria and suppressing beneficial ones.
And studies in mice have found that micro- and nanoplastics cause cell death in the lining of the intestine and increase inflammation in the intestine.
If nanoplastics manage to pass from the digestive system into the bloodstream, the impacts could be much further reaching, starting with heart disease.
There is strong evidence that this can happen. A 2021 study found that when rats were fed water embedded with polystyrene nanoparticles or Styrofoam, those particles began to build up in their hearts, causing the heart to swell with collagen, making it difficult for it to beat and, Ultimately, it caused premature death among heart cells.
And tests in a petri dish found that nanoparticles could destroy human red blood cells, although they could not replicate these findings within real blood.
But as worrying as these laboratory findings are, the risks of nanoplastics currently remain a matter of conjecture. While these particles can be very 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 due to a gap in technology: Without a reliable way to identify nanoparticles in the environment, scientists have not been able to calculate precisely how many particles to expose cells to to test the impacts of exposure.
The Columbia findings take a key step toward closing that gap.
As such, perhaps more significant than the findings themselves, which are alarming but difficult to put into context, was the way the Columbia University team discovered them: through a new method that 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 bouncing light to indicate what plastic polymer is inside.
Compounds like PVC, PET and polystyrene are all “made of different chemical bonds,” Min said. “Those different chemical bonds have different energy, essentially intrinsic. And we can use the 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 the levels of nanoplastics found in the bottles compare to levels in tap water across the country. (The team hopes to begin publishing results for the country’s drinking water supply within the next two years.)
Qian said the baton now passes to toxicologists to determine how the levels the team found in bottled water translate into real health impacts.
“We only took the first step in terms of quantifying the exposure: how much [nanoplastics] there is in the water bottle that we [are] actually exposed every day,” Qian said.
“Once you have the precise exposure, you can do more research on the consequences of toxicity,” he said.
— Updated at 4:55 p.m.
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