While in aquatic environments microplastics can be filtered out relatively easily, in soil it’s much harder to get to these microscopic particles. While you can certainly strip mine an entire area to process its soil, a less invasive method would involve something like the magnetic flakes proposed and demonstrated by [Jeonghyo Kim] et al. in a recent article in npg asia materials.
The Ti3C2Tx flakes, referred to as MXene microparticles, were designed to attract target microplastics. These were then combined with ferromagnetic nickel nanoparticles to make structures that can be propelled through soil using an external magnetic field.
During tests under laboratory conditions the researchers managed to remove about 81% of polystyrene and 72% of PET particles this way from soil, with a correspondingly higher percentage in water. After having the flakes rummage about for a while through the target material, they are removed with a strong magnetic field, which should recover most of them.
Naturally, the question with any such system is how it’ll perform once exposed to real world conditions and its myriad of soil types and conditions.
Microplastics absolutely saturate the Earth’s environment, and that’s probably not a good thing unless you’re looking for a sediment marker for the Anthropocene period. On the other hand, environmental contamination only becomes a really big problem if it bioaccumulates– that is, builds up in the tissues of plants and animals. At least when it comes to worms, that’s not the case with microplastics, according to new research from the Canadian Light Source at the University of Saskatchewan.
Pictured: Not an Igloo. Credit: David Stobbe / Stobbe Photography, via University of Saskatchewan
The Canadian Light Source isn’t just some hoseheads in an igloo with a flashlight– it’s a 2.9 GeV Synchrotron tuned to produce high-energy photons. Back when Synchrotrons were used for particle physics, Synchrotron radiation was a very annoying energy sink, but nobody cares about 2.9 GeV electrons anymore. So rather than slam them into each other or a static target, the electrons just whip about endlessly, giving off both soft- and hard X-rays for material science studies– or, in this case, to observe the passage of polyethelyne microplastic particles through the guts of some very confused earth worms. To make them detectable by x-ray, the polyethylene was bonded to barium sulfate, an x-ray absorber. Equally opaque barium titanite glass microspheres were used with different worms, as a control.
Despite being fed soil enriched with far more plastic than you’ll find outside of a 3D print farm, it seems the worm’s digestive system was able to reject the particles, even those as fine as 5 microns. That’s a good thing, because if the worms were absorbing plastic from the soil, it’s likely their predators would absorb it from the flesh of the worms, so and so forth up the food chain in the sort of cascade that made DDT a problem and makes mercury compounds so serious. If the worms are rejecting these compounds, there’s a chance other creatures can too– and at the very least, it means they aren’t building up on this bottom rung of the foot chain. If you’re looking for a more technical read, the full paper is available here.
It’s too early to say what this means for how microplastics get into humans and other animals, but it’s hopeful. Equally hopeful was the recent finding that studies that don’t rely on football-field sized X-ray machines might be picking up on microplastics from lab gloves, skewing results.
Header image: the digestive systems of earth worms as imaged by the Canadian Light Source. Credit Letwin, et al,
Environmental Toxicology and Chemistry, vgag072, https://doi.org/10.1093/etojnl/vgag072
The topic of micro- and nanoplastics (MNPs) has become increasingly prevalent over the past years, as amidst dismissal and panic, researchers attempt to distinguish just how much of a problem MNPs truly are. The most essential problem here is that we are still developing the tools to accurately measure the levels of MNP contamination. Recently, [Madeline E. Clough] et al. demonstrated in an article published in Analytical Methods how gloves worn in laboratory settings can create false positive MNP signals.
As we covered previously, detecting MNPs is tough due to the detection methods used, many of which rely on interpreting signals from methods like pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS), with protocols for this and other methods still being worked on, particularly on how to filter out false positives.
The article by [Clough] demonstrates how dry contact of lab gloves on samples can deposit stearate salts – left over from their production, which are subsequently misidentified as being MNPs, specifically polyethylene (PE). These false positives occur with µ-Fourier transform infrared (µ-FTIR) spectroscopy and µ-Raman spectroscopy, but can occur with Py-GC-MS as well, as has been determined previously. Substances like the fatty lipids that are commonly found in the human body, and in particular the brain, will closely match the PE signature.
With these very common stearate salts now also a likely source of contamination with MNP measurements, it just becomes more obvious that it’s incredibly hard to make accurate assessments about any hazards of MNPs until we can determine their presence with any level of reliability.
Over the past years there have appeared in the media increasingly more alarming reports about micro- and nanoplastics (MNPs) and the harm that they are causing not only in the environment, but also inside our bodies. If some of the published studies were to be believed, then MNPs are everywhere inside our bodies, from our blood and reproductive organs to having deeply embedded themselves inside our brains with potentially catastrophic health implications.
Early last year we covered what we thought we knew about the harm from MNPs in our bodies, but since then more and more scientists have pushed back against these studies, calling them ‘flawed’ and questioning the used methodology and conclusions. Despite claims of health damage in mice, institutions like the German federal risk assessment institute also do not acknowledge evidence of harm to human health from MNPs.
All of which raises the question whether flawed studies have pushed us into our own Chicken Little moment, and whether it’s now time to breathe a sigh of relief that the sky isn’t falling after all.
To paraphrase The Simpsons: plastics are the solution to – and cause of – all of mankind’s problems. Nowhere is this more clear in the phenomenon of microplastics. Some have suggested that alternative bioplastics made out of starch could be the solution here, as the body might be able to digest and disassemble these plastic fragments better. Unfortunately, a team of Chinese researchers put this to the test using mice, with the results suggesting that starch-based plastics do not change the harm to tissues and organs.
We previously looked at this harm from micro- and nanoplastics (MNP), with humans and their brains at autopsy showing a strong correlation between disease and presence of MNPs. In this recent study mice were split up into three groups, for either no, low or high levels of these bioplastics in their food. At autopsy, the mice exposed to the bioplastics all showed damage to organs, including the same gene-regulation issues and inflammation markers as seen with other plastics.
Despite these results, researchers question how useful these results are, as they pertain to modified starches with known biodegradability issues, while starch by itself is absolutely digestible when it’s in the form of potato chips, for instance. Perhaps the trick here is to make bioplastics that are still useful as plastics, and yet as harmless to ingest as said potato chips.
Not that we recommend eating bioplastics, mind you; potato chips are definitely tastier.
Perhaps one of the clearest indications of the Anthropocene may be the presence of plastic. Starting with the commercialization of Bakelite in 1907 by Leo Baekeland, plastics have taken the world by storm. Courtesy of being easy to mold into any imaginable shape along with a wide range of properties that depend on the exact polymer used, it’s hard to imagine modern-day society without plastics.
Yet as the saying goes, there never is a free lunch. In the case of plastics it would appear that the exact same properties that make them so desirable also risk them becoming a hazard to not just our environment, but also to ourselves. With plastics degrading mostly into ever smaller pieces once released into the environment, they eventually become small enough to hitch a ride from our food into our bloodstream and from there into our organs, including our brain as evidenced by a recent study.
Multiple studies have indicated that this bioaccumulation of plastics might be harmful, raising the question about how to mitigate and prevent both the ingestion of microplastics as well as producing them in the first place.
Like the lead paint and asbestos of decades past, microplastics are the new awful contaminant that we really ought to do something about. They’re particularly abundant in the aquatic environment, and that’s not a good thing. While we’ve all seen heartbreaking photos of beaches strewn with water bottles and fishing nets, it’s the invisible threat that keeps environmentalists up at night. We’re talking about microplastics – those tiny fragments that are quietly infiltrating every corner of our oceans.
We’ve dumped billions of tons of plastic waste into our environment, and all that waste breaks down into increasingly smaller particles that never truly disappear. Now, scientists are turning to an unexpected solution to clean up this pollution with the aid of seashells and plants.
