"Just One Word: Microplastics"

[Recusant]

This may be good news on the "humans ingesting plastic" front, though it seems unlikely to do much good for the rest of the planet.

"New Technique Removes More Than 98% of Nanoplastics From Water" | Science Alert

No one yet knows what threat plastic pollution poses to human health, but the recent realization that we are drinking invisible fragments of plastic along with our water is making many understandably uneasy.

To stop microplastics and nanoplastics from penetrating deep into our bodies and brains, researchers at the University of Missouri have come up with a potentially sustainable and safe way to rid water of microscopic pollutants.

Using natural liquid ingredients that have low toxicity, the team has shown they can remove around 98 percent of nanoscopic polystyrene beads from fresh and salt water.

The solvent that researchers engineered floats on the surface of water, kind of like oil. A quick mix, however, and – voila! – the liquid picks up microscopic plastics in the water and carries them to the surface.

Sucking up the top layer of liquid with a pipette, the team at the University of Missouri (Mizzou) found they could remove nearly all nanoplastic beads from their contaminated water samples.

In salt water, the method worked at extracting 99.8 percent of all polystyrene pollutants.

The proof of concept showcases a cost-effective and potentially "sustainable solution to the nanoplastics problem", argue researchers from Mizzou. With further research, the technique could even prove useful for cleaning water of other pollutants, like forever chemicals.

[Continues . . .]

The paper is behind a paywall.

Abstract:

Nanoplastics pollution, a growing environmental threat, adversely affects ecosystems and human health. The challenge in extracting and detecting nanoplastics from environmental matrices lies in their minuscule sizes, varied shapes, and low concentration.

We demonstrate an efficient approach employing hydrophobic deep eutectic solvents (HDESs) for the liquid/liquid extraction of polystyrene (PS) beads (nominally sized 0.1, 0.2, 0.3, 0.5, and 1.0 μm), a stand-in for nanoplastics, from both fresh and saline water. Of ten different HDES systems evaluated, those described by 1:2 molar ratios of tetrabutylammonium bromide ([N₄₄₄₄]Br):decanoic acid or tetraoctylammonium bromide ([N₈₈₈₈]Br):decanoic acid as well as 1:1 thymol:menthol showed exceptional efficiency, achieving nearly complete removal (a mean extraction efficiency of 98.4%) of nanoplastics in a single pass across a range of nanoplastic sizes from 100 to 1000 nm. The HDES comprising 1:2 [N₄₄₄₄]Br:decanoic acid exhibits a high extraction capacity, effectively capturing at least 17.2 wt % of PS. Crucially, the extractive fluids comprise benign components, and the hydrophobicity of these HDESs helps to prevent water phase contamination, showcasing their potential as a sustainable solution to the nanoplastics problem.

[Recusant]

This one isn't particularly surprising. If anything I'm surprised that it's the first time microplastics have been observed in human brains.

"Microplastics are in our brains. How worried should I be?" | The Conversation

A study from the United States has, for the first time, found microplastics in human brains. The study, which has yet to be independently verified by other scientists, has been described in the media as scary, shocking and alarming.

[. . .]

The study looked at concentrations of microplastics in 51 samples from men and women set aside from routine autopsies in Albuquerque, New Mexico. Samples were from the liver, kidney and brain.

These tiny particles are difficult to study due to their size, even with a high-powered microscope. So rather than trying to see them, researchers are beginning to use complex instruments that identify the chemical composition of microplastics in a sample. This is the technique used in this study.

The researchers were surprised to find up to 30 times more microplastics in brain samples than in the liver and kidney.

They hypothesised this could be due to high blood flow to the brain (carrying plastic particles with it). Alternatively, the liver and kidneys might be better suited to dealing with external toxins and particles. We also know the brain does not undergo the same amount of cellular renewal as other organs in the body, which could make the plastics linger here.

The researchers also found the amount of plastics in brain samples increased by about 50% between 2016 and 2024. This may reflect the rise in environmental plastic pollution and increased human exposure.

The microplastics found in this study were mostly composed of polyethylene. This is the most commonly produced plastic in the world and is used for many everyday products, such as bottle caps and plastic bags.

[. . .]

To get into brain tissue, microplastics must cross the blood-brain-barrier, an intricate layer of cells that is supposed to keep things in the blood from entering the brain.

Although concerning, this is not surprising, as microplastics must cross similar cell barriers to enter the urine, testes and placenta, where they have already been found in humans.

[. . .]

Microplastics are widespread in the environment, and it's difficult to avoid exposure. We are just beginning to understand how microplastics can affect our health.

Until we have more scientific evidence, the best thing we can do is reduce our exposure to plastics where we can and produce less plastic waste, so less ends up in the environment.

An easy place to start is to avoid foods and drinks packaged in single-use plastic or reheated in plastic containers. We can also minimise exposure to synthetic fibres in our home and clothing.

[Link to full article.]

The preprint version of the paper is open access:

"Bioaccumulation of Microplastics in Decedent Human Brains Assessed by Pyrolysis Gas Chromatography-Mass Spectrometry" | NIH/National Library of Medicine

Abstract:

Rising global concentrations of environmental micro- and nanoplastics (MNPs) drive concerns for human exposure and health outcomes. Applying pyrolysis gas chromatography-mass spectrometry (Py-GC/MS) methods to isolate and quantify MNPs from human samples, we compared MNP accumulation in kidneys, livers, and brains.

Autopsy samples from the Office of the Medical Investigator in Albuquerque, NM, collected in 2016 and in 2024, were digested for Py-GC/MS analysis of 12 polymers. Brains exhibited higher concentrations of MNPs than liver or kidney samples. All organs exhibited significant increases from 2016 to 2024.

Polyethylene was the predominant polymer; the relative proportion of polyethylene MNPs was greater in brain samples than in liver or kidney. Transmission electron microscopy verified the nanoscale nature of isolated particles, which largely appeared to be aged, shard-like plastics remnants across a wide range of sizes. Results demonstrate that MNPs are selectively accumulated into the human brain and concentrations are rising over time.

[Recusant]

On the more hopeful side . . .

"New 'Living Plastic' Self-Destructs Once It's Thrown Away" | Science Alert

Scientists have created a 'living plastic' that self-destructs when the material begins to erode.

In the composting process, the novel product breaks down within a month, compared with more traditional versions that take up to 55 days to decompose under the same conditions.

The hopeful technology was inspired by the power of plastic-munching proteins, which are naturally produced by a species of bacteria discovered in 2016 at a recycling facility in Japan.

In the years since scientists have found several other species of bacteria that have evolved the enzymes to eat plastic, and these natural proteins have inspired synthetic versions that are even hungrier for our waste.

Researchers at the Chinese Academy of Sciences (CAS), led by synthetic biologist Chenwang Tang, have now figured out how to bake bacterial spores that secrete these enzymes into the very structure of polycaprolactone (PCL) plastic.

That way, when the plastic begins to degrade, these newly freed enzymes can finish off the task.

[Continues . . .]

The paper is behind a paywall.

Abstract:

Plastics are widely used materials that pose an ecological challenge because their wastes are difficult to degrade. Embedding enzymes and biomachinery within polymers could enable the biodegradation and disposal of plastics. However, enzymes rarely function under conditions suitable for polymer processing.

Here, we report degradable living plastics by harnessing synthetic biology and polymer engineering. We engineered Bacillus subtilis spores harboring the gene circuit for the xylose-inducible secretory expression of Burkholderia cepacia lipase (BC-lipase). The spores that were resilient to stresses during material processing were mixed with poly(caprolactone) to produce living plastics in various formats. Spore incorporation did not compromise the physical properties of the materials. Spore recovery was triggered by eroding the plastic surface, after which the BC-lipase released by the germinated cells caused near-complete depolymerization of the polymer matrix.

This study showcases a method for fabricating green plastics that can function when the spores are latent and decay when the spores are activated and sheds light on the development of materials for sustainability.

[Recusant]

I've missed posting a few items on this beat the past few months--none of them particularly encouraging. This one may at least be helpful. Cutting to the chase: boil it then filter it--even just boiling it can help.

"There's a Surprisingly Easy Way to Remove Microplastics From Drinking Water" | Science Alert

Tiny fragments of microplastics are making their way deep inside our bodies in concerning quantities, significantly through our food and drink.

Scientists have recently found a simple and effective means of removing them from water.

A team from Guangzhou Medical University and Jinan University in China ran tests on both soft water and hard tap water (which is richer in minerals).

"Tap water nano/microplastics (NMPs) escaping from centralized water treatment systems are of increasing global concern, because they pose potential health risk to humans via water consumption," write the researchers in their paper, published in February.

They added in nanoplastics and microplastics before boiling the liquid and then filtering out any precipitates.

In some cases, up to 90 percent of the NMPs were removed by the boiling and filtering process, though the effectiveness varied based on the type of water.

Of course the big benefit is that most people can do it using what they already have in their kitchen.

"This simple boiling water strategy can 'decontaminate' NMPs from household tap water and has the potential for harmlessly alleviating human intake of NMPs through water consumption," write biomedical engineer Zimin Yu from Guangzhou Medical University and colleagues.

[Continues . . .]

The paper is behind a paywall.

Abstract:

Tap water nano/microplastics (NMPs) escaping from centralized water treatment systems are of increasing global concern, because they pose potential health risk to humans via water consumption. Drinking boiled water, an ancient tradition in some Asian countries, is supposedly beneficial for human health, as boiling can remove some chemicals and most biological substances. However, it remains unclear whether boiling is effective in removing NMPs in tap water.

Herein we present evidence that polystyrene, polyethylene, and polypropylene NMPs can coprecipitate with calcium carbonate (CaCO3) incrustants in tap water upon boiling. Boiling hard water (>120 mg L–1 of CaCO3) can remove at least 80% of polystyrene, polyethylene, and polypropylene NMPs size between 0.1 and 150 μm. Elevated temperatures promote CaCO3 nucleation on NMPs, resulting in the encapsulation and aggregation of NMPs within CaCO3 incrustants. This simple boiling-water strategy can "decontaminate" NMPs from household tap water and has the potential for harmlessly alleviating human intake of NMPs through water consumption.

[Asmodean]

...How would boiling remove microplastics? I mean, I suppose some plastics could be degraded by high temperature, or are we talking different sort of mechanics here? (Physics rather than chemistry? I noticed coprecipitation - do them particles sort of... Rise up, boil off, then end up in your lungs rather than stomach..?)

I may need to actually read-read that thing. Interesting.