Although people have been calling for attention and control of the white pollution crisis, it is a frustrating and helpless reality that we are now more and more inseparable from plastic. Plastic products are ubiquitous in food and packaged goods, and global plastic production has exceeded 368 million tons per year.
Due to the continuous rise of global plastic pollution, plastic products will produce a large number of micron-sized plastic particles after slow light, chemical, physical and biological degradation, called microplastics. , abbreviated MP). In recent years, microplastics have been widely found in marine and freshwater ecosystems and can also be detected in air and soil. This makes people wonder, will microplastic particles be enriched in the food chain and digested by the human body? This issue has gradually attracted people’s attention and concern.
Waste material slips onto the table
On September 20 this year, a research team from the University of Otago in New Zealand found that 75% of 10 important commercial fish species (155) caught in a waters in southern New Zealand had Contains microplastic particles, with an average of 2.5 particles/stripe[1]. Among them, the most common types are polyethylene and polypropylene. These two polymers are widely used in automobiles, electrical parts, packaging materials, medical equipment, etc. It is unexpected that these discarded industrial products will be able to wander around one day. Everyone’s table.
▲Microplastic particles were detected in 75% of 155 wild fish in the waters of New Zealand (Image source: Reference [1])
Not just food, but the packaging of food – plastic bags, plastic bottles, coffee cups, etc., will also send a large amount of microplastics directly into people’s mouths, following the American diet. It is calculated that each person eats about 5g of microplastics per week, which is equivalent to the weight of a bank card! (See “Bottled water, takeaways are destroying our bodies! Microplastics found in human blood for the first time…”)
Microplastic particles do not “pass the gut”
Speaking of which, since plastic is so difficult to degrade, even if we eat vegetables and fish containing microplastics and drink beverages in plastic bottles, it should be fine, right? Are microplastic particles ingested by the human body digested? Or just “walk around” people’s digestive tracts? On January 11 this year, the Spanish Institute of Food Science simulated the human digestion process of microplastic particles along the gastrointestinal tract, and intuitively demonstrated the impact of microplastics on the human digestive tract [2].
▲In vitro simulation experiment of the digestion process of microplastic particles (Image source: Reference [2])
The team simulated the complete passage of a single dose of polyethylene terephthalate (PET) through the intestinal mucosa. PET, one of the main polymers used in plastic bottles and caps, has been detected in beverages. Although PET has been reported to be resistant to biodegradation, this study showed a different conclusion: after the PET particles entered the colon, the PET structure gradually became amorphous as high concentrations of organic matter and microbiota were deposited on the surface of the microplastic particles The whole process appears to be a biodegradation driven by gut microbes. Unexpectedly, seemingly indestructible polymer materials can be eaten and decomposed by microorganisms in the body.
▲The digestion process of microplastic particles photographed by scanning electron microscope (FESEM) (Image source: Reference [2])
Ingested PET particles are degraded, so will it affect the intestinal environment? The research team transplanted the fecal suspension of two volunteers into the simulator, reproduced the human colon environment in vitro, and then injected PET MP into the colon simulator to observe the changes of intestinal microecology within 72 hours. Among them, the intake of PET MP is controlled at the closest realistic human daily intake: 166mg/day. The study observed a decrease in the total number and diversity of gut microbiota from both volunteers, including some key gut microbiota responsible for intestinal metabolic biotransformation and microecological stabilization, such as Bifidobacterium and Enterobacter. The ingestion of microplastics alters the composition and diversity of the human microbial colonic flora, which may directly or indirectly cause gut dysbiosis, thereby increasing the risk of digestive diseases.
Although more research is needed to confirm the impact of microplastics on our health, for the sake of the earth we live on, and more importantly for our own health, we should try our best in our daily life. Reducing the use and consumption of plastics seems to be beneficial.
Next time you go out to the supermarket, remember to bring a paper or reusable cloth bag and thermos! It is always right to reduce the consumption of plastic bottled drinks and prevent problems before they happen!
References:
1. Clere, I. K. et al. Quantification and characterization of microplastics in commercial fish from southern New Zealand. Mar PoLut Bull 184, 114121, doi:10.1016/j.marpolbul.2022.114121 (2022).