Fibers

Two recent papers about plastic infiltration into brains issued grave warnings about strengthening research on this pollutant. Paper 1: Concentrations of microplastics found in human brains, livers, and kidneys are rapidly increasing. On average, microplastic levels in 2024 brain samples are approximately 50% higher than in 2016 samples. Furthermore, brain samples contain 30 times more microplastics than liver and kidney samples. Paper 2: Microplastics in mouse brains not only significantly reduced spatial memory capabilities but also impaired motor coordination and endurance.

An author of one study stated: "We want to conduct more research in this area, but the thought that microplastic concentrations in my brain could increase by several percentage points before I find answers sends chills down my spine."

On a weekday noon, when you heat lunch by placing a plastic container in the microwave, this process releases massive amounts of microplastic particles into your food. What you swallow isn’t just a delicious meal—microplastics hitchhike into your body. This raises a critical health question: Could long-term accumulation of microplastics harm your health?

A recent Nature news feature reported a landmark study in Science Advances []. A team including Xi Beidou and Hou Jiaqi (co-corresponding authors) from the Chinese Academy of Environmental Sciences, Huang Haipeng (first author) from Peking University’s Future Technology Institute, and two other researchers tracked microplastics migrating through mouse brains in real time:

Microplastics were engulfed by immune cells, deforming them into irregular shapes. These cells then flowed rapidly through blood vessels before becoming trapped in the winding capillaries of the cerebral cortex—a scene resembling a "car crash pileup." This ultimately caused cellular blockages, induced cerebral thrombosis, and triggered neurobehavioral abnormalities.

The vivid imagery suggests catastrophic consequences from massive microplastic accumulation...

Part 1: Where microplastics come from and where they go

In 2004, marine ecologist Richard Thompson’s team at the University of Plymouth published a seminal one-page Science summary [] compiling a decade of startling discoveries from UK coastlines and seabed sediments. Thompson coined the term "microplastic" to describe plastic particles under 5mm. Today, the precise diameter range is defined as 1μm–5mm.

True to their name, microplastics are inseparable from plastic itself. Since its 1950s inception, plastic has permeated industrial production, transportation, medical care, and daily life. Statistics show global annual plastic production surged from 2 million tons in 1950 to over 450 million tons by 2020 [].

However, recycling efforts remain inadequate for this deluge. In 2019, only 9% of plastics were recycled globally [], while 69% underwent traditional disposal (landfilling/incineration), and 22% were mismanaged in the environment []. Abuse and improper disposal of plastics constitute primary microplastic sources.

Early microplastic research focused on personal care products—plastic particles escaping during manufacturing, fragments from discarded bottles/waste—all washed into rivers/oceans. In 2015, oceanographers estimated 15–51 trillion microplastic particles float in global surface waters.

Later discoveries revealed other sources: particles shed from vehicle tires, synthetic microfibers from clothing. These particles now permeate air, soil, and water.

Over two decades, global teams including Thompson mapped microplastic distribution: From Everest’s snow/streams [] to polar ice/new snow [], from Atlantic/Mediterranean/Indian Ocean sediments [] … Microplastics float in air, fall with rain onto mountains/forests/cities, and contaminate food, drinking water, even beer. Scientists thus assert []: "Nearly all species have encountered microplastics."

In 2021, Wageningen University environmental scientist Albert Koelmans’ paper [] estimated—based on limited surveys of air/water/salt/seafood—that children/adults likely ingest 10 to >100,000 microplastic particles daily. Worst-case scenarios suggest annual human ingestion equals a credit card’s weight.

The crisis escalates. With current annual plastic production exceeding 400 million tons, projections indicate doubling by 2050. Even if plastic production magically halted tomorrow, existing plastics in landfills/environment (~5 billion tons) would keep fragmenting into microplastics.

Part 2: Microplastics pervade human bodies

Norwegian biologist Martin Wagner notes: Though "microplastics" emerged 20 years ago, human health impact studies only began ~10 years ago.

In 2019, Philipp Schwabl’s team at Medical University of Vienna reported in Annals of Internal Medicine [] the first detection of microplastics in human feces. This small study of 8 participants from Europe/Japan/Russia found microplastics in all stool samples. Up to 9 plastic types were identified among 10 tested, predominantly polypropylene and PET.

On average, 20 microplastic particles per 10g of feces were found—some from cosmetics, others from degraded plastic waste. Authors estimated "over 50% of global population likely has microplastics in feces," urging larger confirmatory studies. While confirming long-suspected gut infiltration, implications for bowel disease patients remain concerning [].

Today, microplastics have been detected in human digestive, respiratory, cardiovascular, and reproductive systems—organs, bodily fluids, excreta [] —proving prolonged cohabitation with humans.

A February 2024 Nature Medicine study [] delivered grimmer news: Analyzing postmortem human liver/kidney/brain samples, Matthew Campen’s team at University of New Mexico found surging plastic production correlates with rising organ microplastic concentrations. 2024 brain samples showed 50% higher microplastic levels than 2016 samples. Brains also harbored 30× more microplastics than livers/kidneys, indicating preferential brain accumulation.

The aforementioned Science Advances paper provided imaging evidence of aggregation processes. Mice drinking water with fluorescent polystyrene microspheres revealed—via two-photon microscopy—particles moving through blood vessels as described earlier… Some blockages resolved during 4-week observation, others persisted.

Part 3: Health hazards of microplastics

Persistent microplastics demand urgent attention.

Xi’s team further demonstrated consequences of cerebrovascular microplastic blockages in mice. Y-maze tests showed mice drinking microplastic-laced water exhibited significantly impaired spatial memory, motor coordination, and endurance. Weight loss suggested altered feeding behaviors from reduced mobility.

While emphasizing uncertainty about human parallels (given larger brain vasculature and faster blood flow), authors stressed []: "Increased investment in this field is urgently needed to fully understand health risks from bloodborne microplastics."

Current research increasingly probes microplastic impacts on human organs, though ethical constraints limit human trials. Scientists rely on mouse models and human cell/organoid systems.

A December 2023 Environment International study [] by Xu Mingkai’s team at Chinese Academy of Sciences revealed: After 28 days of oral polystyrene micro/nanoplastic exposure, mice showed gut accumulation causing pathogenic bacteria proliferation, beneficial bacteria reduction, disrupted short-chain fatty acid metabolism, intestinal inflammation, barrier dysfunction, and immune disruption—alarming findings.

A landmark March 2024 NEJM study [] reported: ~60% of 250 cardiac surgery patients had microplastics in their aortas. Those with plastic accumulation faced 4.5× higher post-surgery risks of heart attack/stroke/death within three years. A November 2024 Ecotoxicology and Environmental Safety paper [] warned that high temperatures accelerate microplastic release from containers, potentially altering gut microbiota to induce systemic inflammation/oxidative stress—raising heart failure risks.

Indeed, recent studies link microplastics to human cancers [], kidney diseases [], fertility issues [], and even Alzheimer’s []. However, no direct causative evidence exists—only correlations.

Beyond microplastics, scientists worry about nanoplastics (<1μm). Data suggest [] larger particles may pass through digestion, but nanoplastics could infiltrate cells with no biological clearance mechanisms.

Now omnipresent, microplastic pollution can’t be ignored. Scientists race against time to develop new imaging/tracking/analysis methods. As Campen told Nature: "We want to do more research, but the chilling reality is that my brain’s microplastic concentration might rise several percentage points before we get answers."

[1]https://www.science.org/doi/10.1126/sciadv.adr8243#sec-3

[2]https://www.science.org/doi/10.1126/science.1094559

[3]https://ourworldindata.org/plastic-pollution

[4]https://chn.oversea.cnki.net/kcms/detail/detail.aspx?filename=HJKZ202308050&dbcode=CJFQ&dbname=CJFDLAST2023&uniplatform=NZKPT

[5]https://linkinghub.elsevier.com/retrieve/pii/S004896971933323

[6]https://www.sciencedirect.com/science/article/pii/S2590332220305509

[7]https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2014EF000240

[8]https://royalsocietypublishing.org/doi/10.1098/rsos.140317

[9]https://www.nature.com/articles/d41586-021-01143-3

[10]https://pubs.acs.org/doi/10.1021/acs.est.0c07384

[11]https://www.acpjournals.org/doi/10.7326/M19-0618

[12]https://www.theguardian.com/environment/2018/oct/22/microplastics-found-in-human-stools-for-the-first-time#:~:text=Microplastics%20have%20been%20found%20in，found%20to%20contain%20microplastic%20particles.

[13]https://kns.cnki.net/kcms2/detail/11.1895.X.20230524.1541.002.html

[14]https://www.nature.com/articles/s41591-024-03453-1

[15]https://www.theguardian.com/environment/2025/feb/11/microplastics-mice-brains

[16]https://iae.cas.cn/gb2019/xwzx_156509/kyjz/202311/t20231129_6938725.html

[17]https://www.nejm.org/doi/10.1056/NEJMoa2309822

[18]https://www.sciencedirect.com/science/article/pii/S0147651324014593#sec0150

[19]https://pubs.acs.org/doi/10.1021/acs.est.3c09524

[20]https://www.sciencedirect.com/science/article/abs/pii/S0269749123019115?via%3Dihub

[21]https://academic.oup.com/toxsci/article-abstract/200/2/235/7673133?redirectedFrom=fulltext&login=false

[22]https://link.springer.com/article/10.1007/s12035-023-03625-z

[23]https://www.nature.com/articles/d41586-025-00405-8