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For the very first time, scientists have watched nano-plastics—the even smaller, even trickier kind of microplastic—enter a living animal cell. It wasn’t that we needed confirmation this could happen, because we’ve known that for years; it’s that we’d never seen it happening in real time, and we didn’t know the exact mechanisms behind it. The new research underlines how little we still know about microplastics, despite growing recognition they may be one of the greatest threats to human health today. Exposure has been linked by one reproductive-health expert to a civilizational decline in sperm counts that could make natural reproduction impossible as early as the middle of this century.
The study, published in Environmental Science: Advances, was conducted by scientists at Tokyo University of Science in Japan. They created special nanoplastic particles and then dyed them using a fluorescent dye, so they could be tracked easily once they entered animal cells in the lab.
Almost all prior research on microplastics has used spherical beads of polystyrene, mainly because they’re easy to produce and work with. But these beads aren’t like the microplastics humans and animals are actually exposed to. Most microplastics are irregular and jagged in shape, the product of environmental wearing of one form or another: sunlight, mechanical abrasion—being bashed by waves, trampled underfoot, shearing off rubber wheels as they run across tarmac, etc. —and digestion by organisms including bacteria, fungi and plankton.
(It’s reckoned a single rotifer—a species of plankton—can produce between 348,000 and 366,000 nanoplastic particles every day. In China’s largest freshwater lake, Poyang, researchers estimate plankton may be producing 13.3 quadrillion nanoplastic particles a day. There are fifteen zeroes in a quadrillion, by the way.)
Realism matters in scientific experiments, and microplastic research is no different. Studies have already shown that different shapes have very different effects. Irregular microplastics have far more serious effects on the swimming ability of small fish, for example, and they also spend more time in the digestive tracts of crustaceans than perfectly regular spheres.
The specially prepared realistic nanoplastics were made to fluoresce using a dye called “Nile red” and then added to blood proteins to prevent them from clumping together. Different kinds of plastic were used, so the researchers could study whether they behaved differently when entering animal cells.
Fibroblast cells, a common type of cell found in the connective tissue of mammals, were then exposed to the fluorescent nanoplastics for 30 minutes, washed, and examined under a special electron microscope.
The researchers discovered that the plastics had accumulated in the cells’ cytoplasm—the gooey interior—around the nucleus, where the genetic material is stored. This suggests, clearly, that the particles were absorbed into the cell in the same manner as useful products like nutrients are brought inside. The process is known as “endocytosis,” and involves wrapping substances in special membranes that allow them to cross the cell wall and get inside.
In basic terms, natural healthy cellular processes are helping to smuggle in toxic pieces of plastic.
None of this is particularly exciting or sexy, and I apologise if, up to this point, I’ve struggled to hold your attention.
A little bit of context should liven things up a bit.
More than nine billion tons of plastic are estimated to have been produced between 1950 and 2017, and over half that total has been produced since 2004. The vast majority of that plastic has ended up in the environment, where it breaks down into smaller and smaller pieces of plastic, some of which will end up in our bodies.
Nowhere on earth is untouched by plastic pollution now, not the Antarctic, or even the deepest ocean trench. Microplastics circulate like a force of nature, in water, in the air and in rain and snow. Researchers estimate 43 trillion pieces of microplastic land on Switzerland in snow every year, the equivalent of 3,000 tons. Up to 10% of the microplastics may have come from winds and weather taking place in the Atlantic, 1,200 miles away.
Within our homes, microplastics are mainly produced when synthetic fibres from clothes, furnishings and carpets are shed. They accumulate in large quantities in dust and float around in the air, which we then inhale. It’s reckoned this is where the vast majority of exposure takes place, but there needs to be more research to quantify exposure in a way that’s truly meaningful.
Microplastics have been found in pretty much every animal and human tissue you could care to name. Studies have shown that microplastics are found in human heart, liver, lung, genital and womb tissue. Animal studies have also shown that microplastics cross the blood-brain barrier, the brain’s only line of defence against pathogens and harmful substances. Polystyrene microplastics fed to mice ended up in their brains within two hours. Another study showed that inhaled nanoplastics also end up in the brains of mice.
A Chinese study a couple of years ago found microplastics inside people’s eyeballs, in the liquid itself. Whether they get there in the blood from elsewhere within the body, whether they enter from the external surface of the eyeball, or whether they’re in our eyes “pre-formed” from birth—or indeed some combination of all three—is unclear at present. A pair of reusable contact lenses has been estimated to shed over 90,000 plastic particles in a year of use.
New studies are appearing at a steady pace, linking microplastic exposure to virtually every disease and malady you can think of, from irritable bowel syndrome, obesity and autism, to cancer, Alzheimer’s and infertility. There’s a very real chance that the explosion of chronic disease we’ve seen over the last century in the developed world is a direct result of our growing exposure to plastic and plastic chemicals. It’s worth remembering that the first fully synthetic plastic—Bakelite—was only manufactured in 1907, but plastic didn’t really start to be used in massive quantities until the middle of the last century.
The infertility crisis is particularly dire, with one reproductive health expert, Professor Shanna Swan, warning that as early as 2045, man could be unable to reproduce by natural means. On current trends, the median sperm count is set to reach zero in that year, which means that one half of all men will produce no sperm at all, and the other half will produce so few they might as well produce none. Professor Swan believes exposure to plastics is a significant cause of the crisis, as she lays out in her recent book Count Down.
These wide-ranging negative effects happen for a number of reasons. First there are the actual properties of the microplastics themselves: they can physically block narrow tissues, cause inflammation and immune response and also absorb substances, including hormones like testosterone, rendering them unusable by the body. Then there’s the fact that plastics act as vectors for harmful endocrine-disrupting, obesogenic and carcinogenic chemicals, allowing them to be carried into every one of the body’s tissues, where they can cause all sorts of damage.
If we really want to get a hold of this crisis, we need research that stands up to the closest scrutiny. Using the wrong type of microplastic in research could lead scientists to underestimate the harmful effects and even dismiss them, despite mounting evidence.
And if I’m not mistaken, there seems to be a growing attempt to do precisely that: to suggest the health hazards of microplastic exposure are greatly exaggerated, that we’re getting worked up about a problem that doesn’t really exist.
It’s not hard to see who would benefit from this. Plastic manufacturers have already lobbied hard and successfully to prevent new worldwide regulation to curb pollution—a so-called “global plastics treaty” —and if they aren’t already funding research to discredit their critics, as processed-food manufacturers have done with their toxic products, it will happen sooner rather than later. Let’s not give them a helping hand.
