How risky are microplastics?
by Udo Pollmer, September 10, 2025
To this day, no one seems to know exactly what these tiny particles do. After all, they are unimaginably small. For many experts, this is reason enough to put together a scary package of...
...speculations and present it to the public. There is hardly a disease left that microplastics are not supposed to be the cause of.
Yet we have had experience with microplastics for over half a century. Back then, Gerhard Volkheimer conducted extensive experiments at the Charité hospital: he fed tiny PVC beads measuring around 5 to 100 micrometres in cream or bouillon to laboratory animals. He always found PVC in their blood. (1) The result was surprising, as PVC was considered indigestible. After all, the particles were a thousand times larger than what the intestinal villi can absorb via their enterocytes.
Just a few minutes after feeding 200 g of PVC powder to dogs, a dozen particles per millilitre were found in their blood. The same was true for the blood of pigs, goats, guinea pigs and chickens. PVC was also detectable in bile, urine and cerebral fluid. (2)
Pollen, cellulose particles, fibres and fine crystals were also regularly absorbed in considerable numbers by the digestive tract of the test animals: (3) yeast cells from fresh baker's yeast, spores, parasite eggs, as well as diatoms, a pesticide used in organic farming. All of these were found in the blood and, in isolated cases, also in the cerebrospinal fluid. (1) The process is known in technical terms as persorption, as opposed to the resorption of individual nutrients.
Further experiments showed that starch grains behave exactly like PVC particles. The advantage of starch as a natural food component is that it can be easily stained with Lugol's solution in the blood and thus detected. Even back then, the behaviour of spherical microparticles was clarified using starch grains. (2)
After consumption, the grains are found throughout the body, reaching breast milk and even the foetus's circulatory system. Once again, starch grains were repeatedly found in the cerebral fluid and capillaries of test animals, which may explain why students complained of headaches after consuming a starch suspension in self-experiments.
Raw, ungelatinised starch granules are found in significant quantities in wheat flakes, wholemeal products and muesli. Although only about one in every 50,000 grains is absorbed, consuming 100 grams still allows a large number of starch grains to enter the bloodstream. Of the more than 10,000 foreign bodies, roughly more than 1,000 enter the cerebral fluid. (4) Experiments with dogs have shown that embolisms occur in the capillaries, which eventually scar. This raises neurological questions. However, it was not until around 1990 that this was considered a cause of dementia. (4) And very quickly forgotten again, because bird feed is supposed to be so incredibly healthy for us humans.
Now the topic is coming up again. Microplastics are now said to be the cause of dementia. (5) In fact, all kinds of plastic particles have been found in the brains of deceased people, according to a study in Nature. In total, hold on to your hats, several grams per person. Mostly polyethylene, but also nylon, PVC and others. (6) Several grams of plastic waste in the brain seems quite strange.
The German Medical Journal titled its report on this study: "Concentration of microplastics in the human brain has increased". This is incorrect, as it was not microplastics at all, but exclusively nanoplastics, which are thousands of times smaller, in the form of ultra-small "shreds". In view of the feeding experiments with PVC pellets, this cannot actually be the case. Why is spherical microplastic missing here? And what about the many other materials that should also be present as dust, which Volkheimer has detected in the cycle or in the brain?
Despite all the doubts about the study, let us assume, until proven otherwise, that the findings at least provide an initial insight into the overall picture.
Research for carnival
The confusion between microplastics and nanoplastics in a medical journal is probably the result of media confusion caused by deliberately vague definitions: microplastics were arbitrarily defined as particles ranging from one thousandth of a millimetre, i.e. one micrometre, to half a centimetre. From invisible to almost as big as confetti. This absurd distinction shows that this is not a scientific definition, but an "activist" one. Otherwise, the limit would be one full millimetre. Now, fundraisers can finally show photos of finely chopped plastic crumbs on a teaspoon or fingertip. Simple dust from a vacuum cleaner bag is not suitable for fear propaganda.
Even tinier particles in the nanometre range, i.e. less than a micrometre down to a thousandth of a micrometre, are correctly classified as nanoparticles. When microplastics are crumbled, countless nanoparticles are created. That is why nanoparticles are naturally often ten times more common than microparticles.
Most experts suspect food as the source (7). Many kitchen utensils such as coated pans, chopping boards and plastic dishes release large amounts of particles during daily use. Every utensil, whether it's a mixer, kitchen sponge or dishwasher hose, leaves microplastics on food or dishes that are then eaten (8). (Plastic splints used at night to prevent teeth grinding (bruxism) cause even higher levels of exposure. Within a year, they can be completely chewed up and "eaten away".)
When chopping vegetables or herbs on a chopping board, there is a lot of abrasion. Every single cut releases between 3 and 300 microparticles from plastic boards, depending on the quality of the plastic and the force of the cook. (8) Wood seems more appealing – but is it also better? According to a US study, wooden boards released 10 times as many microparticles as plastic ones. The wood particles were even the same size and shape as the plastic particles. (9) But no one seems to be afraid of "micro-wood", even though it has a similar problem. I praise the salad factory with its stainless steel equipment.
Microwave meals in plastic are considered "microparticle slingshots". Even during storage, many particles apparently get into the frozen contents. When bags of frozen goods are stacked, tiny breaks occur, which lead to fragmentation of the plastic under the influence of water. A study from Nebraska found that when stored for more than six months, “can also release millions to billions of microplastics and nanoplastics”. The packaging remains completely intact and sealed. When the packages were heated in the microwave, the number of particles increased tenfold. (10)
For disposable items such as to-go cups and takeaway boxes, the published values range from one trillion nanoparticles to millions of microparticles to a dozen microparticles per container (11-15). Even with these enormous numbers, the quantities are usually in the microgram range. (16) So there is no cause for concern. Especially when you consider that the microparticles often came from the kitchen staff's clothing. (15)
Critics also suspect that much of this is not nano- or microplastic at all, but rather crystallised slip additives such as behenamide (docosanamide). (27) These are lubricants that are added to the plastic mixture during production so that they migrate to the plastic surface. Others suspect oligomers, which strictly speaking are not microplastics either, but rather residues of incomplete polymerisation. (18,19) Such considerations are probably also one reason why many expert authorities do not join in the activists' cries of doom.
Tea bags
The results are relatively consistent, at least for the rather inconspicuous tea bags – but this does not rule out the possibility that slip additives or oligomers have found their way in, which would be just as critical (20). According to various analyses, millions or even billions of microparticles plus billions of nanoparticles end up in the cup when the tea is brewed. (21-24) In the case of nylon bags, the amount of particles released even amounted to one milligram per cup. (25) This is probably due to the soft, elastic and fluffy tea bags, in contrast to the smooth surfaces of plastic cups, which release far fewer particles.
If you want, you can use paper tea bags as an alternative. These are not so easy to recognise, because plastic is processed in such a way that it feels like cellulose. If it is actually cellulose, then it has been impregnated with plastic: without a protective film, it would dissolve like toilet paper when scalded with boiling water. This means that billions of nanoparticles also end up in the cup with cellulose bags. (21) If you like, you can be afraid or imagine how unimaginably small the particles must be if they all fit into a cup and you can't even see them.
"Bioplastic" made from polylactic acid is not an alternative. The raw material lactic acid is usually produced from starch or sugar by genetically engineered bacteria and moulds. Polylactic acid is then synthesised from this using plastic production methods. The result for tea drinkers: one million tiny particles per bag. (26) Popular plastic additives such as tris(2,4-di-tert-butylphenyl) phosphite can also leach out of bioplastics.
Phytopharmacologists will shake their wise heads, because for them, the focus is on the many plant toxins that have already been found in teas. And rightly so: just think of the exorbitant levels of pyrrolizidines in rooibos. In southern Africa, similar-looking poisonous plants were harvested and sold here as rooibos tea. Many areas where red bush is cultivated were virtually contaminated with ragwort. (27,28) Pyrrolizidines destroy the liver like clockwork. In comparison, microplastics are nothing. (29) The tea trade should now have the problem under control; this is just one example.
Better a pint of beer than a tub of Eickel
Now, sensible people generally stay away from herbal teas, regardless of which bags the dried and shredded weeds dangle from; they consider tea bags to be "dirt bags" that are unceremoniously thrown away after a hot bath. Instead of sipping the warm "bath water" from fine porcelain, thirsty people prefer to reach for a jug of cool beer. But microplastics float in that too. They usually get in via additives: e.g. via polyvinylpolypyrrolidone, or PVPP for short. This is a plastic granulate that brewers use to preserve their purity law liquid. PVPP binds tannins and polyphenols. (30) Ultimately, everything except for tiny residues is filtered out again – hence no declaration. While a cup of herbal tea is teeming with chemicals, a pint of lager from the barrel contains at most a few dozen particles. (31)
But not all beers are the same. And no one knows exactly what the particles really are. This is because PVPP is not detected by standard analysis methods. Analysts suspect that it may even be confused with kieselguhr, i.e. diatomaceous earth powder, which was used in the pre-filtration process. (32) Otherwise, beer is clear-filtered with filter cartridges to remove bacteria and yeast cells. Depending on the brewery, suspended solids larger than 3– –micrometres, and in any case larger than 10 micrometres, are separated out. This ensures that the beer is largely free of microparticles when it is bottled. (33) The yeast that the customer sees is usually a subsequently added and dead "show yeast". After all, our brewers like to fish in "naturally cloudy" waters.
Croatian beer: more than just hops, malt and yeast
Unusual substances have been found in PET beer bottles of Croatian origin, such as tomatin, a toxin that tomato plants use to ward off pests, and amygdalin, the poison found in bitter almonds. The latter could be explained as a natural ingredient if it were a cherry-flavoured lambic beer. (34) Even more dubious is the digitonin found in Balkan beer: this is the poison found in foxgloves. (35) It was probably used to make the yeast more pliable, as it increases the permeability of the cell wall. (36)
Substances such as 3-aminopropyltrimethoxysilane are easier to interpret. This prevents gas permeability in plastic bottles, or 3-(2-imidazolin-1-yl)propyltriethoxysilane and heptyl-β-d-glucopyranoside, both of which are additives used in plastic production, especially PET. Then there is dimethyl vinyl phosphonate, a flame retardant. Beer does not burn, but plastic does. Not to mention thiodiethylene glycol, another typical "contaminant" in Croatian wine (35). Not only does it have many uses in the manufacture of plastic, it is also a close relative of diethylene glycol, once popular as an antifreeze agent in Austrian wine.
This was just a selection of the many "additives". Presumably, these are only ultra-trace amounts, as the authors do not provide any information on concentration. (35) Before we point the finger at the breweries, we should be aware that as analysis techniques advance, not only are more foreign substances being detected, but also in ever lower concentrations. This increases the perceived threat potential of foreign substances, but not the risk.
The real particle problem faced by the hearty drinker has another cause. Here, mineral water gave the analysts their first clues. Contrary to expectations, microplastics were regularly found in water bottles. Detailed analyses showed that it came from screw caps and crown caps, for example. (7,37,38) A Bavarian study found 3,000 particles per litre in mineral water in disposable plastic bottles. In glass bottles, 10,000 particles were not uncommon. (39)
The situation was bleak in reusable bottles: hundreds of thousands of particles per litre. However, these do not count as microplastics, but as pigments. (37) The cause was labels made from recycled paper. These had left a lot of pigment particles in the washing water, which then stuck to the bottles. For consumers, however, it makes no particular difference whether it is microplastics or micropigments. But if the bottles are no longer rinsed thoroughly, the brewery at least gets good marks in the eco-audit because it saves water. It can be assumed that this stuff also accumulates in the brain, but this has not yet been researched.
The French Food Safety Authority (ANSES) confirms that glass bottles are the most contaminated. Plastic bottles performed better. Cans were reportedly largely free of microplastics. (37) What sounds logical is remarkable because cans are usually lined with plastic on the inside: “Many different can coatings are commercially available … Coatings contain different additives, e.g. agents to increase surface slipping as well as abrasion and scratch resistance of can coatings, lubricants, anti-foaming agents, adhesives, scavengers for hydrochloric acids, and pigments." (40) Let's wait and see what else is found.
In plastic bottles, carbon dioxide contributes to contamination. (8.41) When the tiny bubbles burst, they release fine particles onto the bottle wall through cavitation. To get an idea of the power of cavitation: it even breaks down ship propellers. Their rotation creates negative pressure on the inside of the propeller blades, which in turn generates bubbles that attack the metal ( ). In beverage bottles, the pressure inside the bottle amplifies the effect. With reusable bottles, the damage increases with each refill.
As we can see, these issues are quite complex. Please do not forget: carbon dioxide is a preservative. It suppresses germs. This is good for our health. That is for sure!
Analysis: a lottery
Nano- and microplastic analysis is an uncertain business. The fluctuations are enormous, partly because each method detects different particle sizes – which is no surprise given the spectrum ranges from half a centimetre to a few nanometres. The contamination levels of the samples tested also vary enormously. What's more, there are many different types of plastic, which are difficult to identify with certainty in such unimaginably small quantities. They corrode in the environment and in the body, so that in many cases they can no longer be detected during analysis. (42)
Often, the particles found are not microplastics, but plastic oligomers and additives, pigments from washing water or fibres from textiles. It may sound like a joke, but some alarming results were caused by laboratory coats whose cotton fibres contaminated the samples. (43, 44)
Contamination can also occur via measuring instruments and reagents. Nanoplastics are so incredibly tiny that the results must always be treated with caution. Even filtering is fraught with pitfalls, for example because the particles get stuck in the filter pores unnoticed, resulting in the contents being underestimated. Reliable results are only possible in the microparticle range.
"Even the most widely used methods are still under development," according to the scientific press, and MP/NP analysis is still far away from method validation and standardization." (45) The analysis of nanoplastics in particular can be regarded as a dubious form of fortune telling. (46) So there is still a lot to be done!
Ultra-embarrassing
According to an internet narrative, "ultra-processed" foods are said to contain ultra-high levels of plastic. Fast food is said to be completely contaminated. (47,48) Anyone who believes this should stand at the edge of a wheat field and snack on the unadulterated grain straight from the stalk. However, the stalks must be thoroughly washed before biting into them, as they are full of dust and microparticles, as can be seen from the dust cloud of the combine harvester during harvesting. Microplastics are also inevitably present. Given the extensive processing steps involved in milling and baking, bread can certainly be considered ultra-processed. Incidentally, according to the mills, our wholemeal flour is their most heavily processed product. (49) Wholemeal bread is often not what health-conscious people think it is.
In this crazy scenario, fresh fruit and vegetables are considered the alternative. Researchers in Catania, Sicily, claim to have detected abundant particles measuring around 1 to 2 µm in the country's produce. This is close to the limit for nanoparticles. They found the most in apples, with around 200,000 particles per gram. In general, fruit contained more particles than vegetables. Carrots were particularly affected, but broccoli and lettuce were also affected. (50)
The study was rightly met with scepticism, partly because the authors did not reveal exactly what material they had detected. This would be important in order to be able to classify their results. It has long been known that particles of all kinds, including germs, enter plants via irrigation water – both through the roots and the leaves. (51-53) Perhaps the water comes from sewers, which is likely in arid regions. In poverty-stricken regions, untreated sewage from hospitals is also used for vegetable fields and orchards because it contains abundant fertilisers. Basically, however, the use of domestic sewage sludge is sufficient. It contains all kinds of filth. Suppliers can assure consumers with a clear conscience that their produce has been grown without artificial fertilisers. Microplastics are then the least of their problems.
A Turkish study came to a completely different conclusion than the one in Sicily: tomatoes contained a maximum of 44 particles per gram, followed by cucumbers with 43. Pears and apples were almost neck and neck. (106) The analysts did not focus solely on larger objects in the micrometre range. After all, this time it was definitely plastic. So who is right? The study from Sicily or the one from Turkey? One is probably as right or wrong as the other.
Anyone who takes such results too much to heart and gives up fruit will soon have to eat laboratory chemicals, as these are the only ones that are particularly pure. Let's not forget that plastic packaging significantly extends the shelf life of many types of fruit and vegetables, meaning that much less is thrown away than with unpackaged goods. This reduces the burden on the environment.
Fishing in murky waters
But there was something else that fearmongering propaganda seized upon: sea fish. Together with seafood, it was said to be the main source of contamination. The sea was supposedly drowning in microplastics. Mussels are said to contain up to 10,000 particles per kilo. In the North Atlantic alone, tens of millions of tons of nano-sized particles are said to be floating around. (54)
First of all, mussels live off dirt. They love nutritious water. Near the coast, among other things, there is mud and plastic debris broken up by the sun and waves. Mussel beds clean the sea. A single mussel filters up to two litres per hour. If the water is rich in nutrients, it is ready for harvest after just two years. After harvesting, mussel farms water their mussels in so-called wet warehouses: the mussels clean themselves in saltwater basins. This depuration also reduces the microplastic content. (55) Unfortunately, this technique does not work with vegetables.
The key point is that almost all of the microparticles are found in the intestines and gills (31, 55) – and these are not usually eaten. The flesh of the mussel is usually okay, and the same applies to shrimps. (46) In order to find anything at all in sea fish, the offal is analysed instead of the fillets. Nevertheless, the Thünen Institute in Bremerhaven identified only a few microparticles in the intestines of dab from the North Sea. (56) The levels in fish flesh are generally considered "negligible". (17,57) If anything, it is mainly textile fibres that are found, which are at least partly due to the work clothing of the staff (fish trade & laboratory). (58) This means that the meat of marine animals is a relatively clean food in terms of microplastics.
This is also confirmed by stool analyses of Indonesian fishermen. If there were any truth to the microplastics campaign, then the contamination would be particularly high among them. In almost half of the samples, nothing was found at all. (59) The fish, mussels and shrimps analysed on site were free of microparticles. (60) Instead, drinking water and tempeh (made from soya) turned out to be sources of plastic. (59, 60)
Vienna sausages
In people from industrialised countries, on the other hand, microplastics are found in abundance in the large intestine. Often ten times as much as in other organs. (8) Since the intestinal tract has had to cope with many undesirable substances since time immemorial, whether secondary plant substances, mould spores or bacteria, it constantly renews its cell lining. In doing so, it gets rid of many harmful substances. Consequently, most microplastics are also excreted in the faeces.
On average, one kilogram contained around 2,000 particles measuring 50 to 500 µm. (61,62) Larger particles are the exception. No wonder: no one consumes plastic crumbs that can be seen or tasted. A recent study from Vienna found an average of 4,000 particles per kilogram. (63) Faeces are difficult to define in terms of weight: some people produce hard stools, others produce soft, butter-like four-pounders – depending on how much water the colon has recovered from the faeces.
The Viennese researchers even attempted to shed light on the connection between diet and excretion. The test subjects first ate as usual, then consciously ate a low-plastic diet, and finally ate a diet high in plastic. When they avoided plastic, there was only a shift in the types of plastic in the faeces; there was no reduction in the amount. But when they consumed a particularly high amount of plastic, the number of particles was almost halved. (63) So much for the current state of knowledge among experts.
Despite the small group of 15 test subjects, the researchers do not report average values, only the median. They boldly claim that it is clear that the degree of processing plays an important role. Wrong, the only thing that plays a role here is the degree of deception. (63)
The authors' note that they most often found fibres rather than particles is revealing: "This suggests that the majority of the fibres might originate from textiles (polyester textiles)." (63) How true! Fortunately, most goods today are packaged in plastic to protect them from contamination. The fibres probably came from "home textiles": they stuck to the dishes when they were dried. The researchers then find this in the faeces and recommend a "low-plastic diet".
Microplastics – the new brain food?
The question remains: where does all the plastic in the brain come from – assuming the data is correct? One previously overlooked route of absorption would be the skin. Although it is supposed to protect against foreign substances, many people are thrilled when they manage to use expensive creams to smuggle all kinds of additives into deeper regions, without realising that sooner or later, the circulatory system and, as a result, the upper chambers of the customer's brain could also benefit from unusual nanoparticles. (5, 64-67)
Not to forget the lungs. Respiratory masks are an important source: „The increased consumption of masks during the COVID-19 pandemic has dramatically increased human contact with microplastics“, states one study. (68) Pulmonary lymph flow allows nanoparticles smaller than 1 µm to pass from the interstitium into the bloodstream. (69) But on the way to the lungs, there is another direct connection to the brain: the olfactory nerve.
In fact, the same material found in the brains of deceased individuals was also found in the olfactory nerve. (70) It is like a conveyor belt that transports dust, metal particles and viruses from the nose to the olfactory brain. This has been proven in many ways over decades. (71-75,103) Even an amoeba-like parasite called Naegleria fowleri enters the brain in this way. (70) It is not without reason that the olfactory brain is damaged in many neurological disorders. (76,77)
Our olfactory organ probably has the edge as a transport route. This is also suggested by the study that found large amounts of plastic in brains: the number of particles was almost ten times higher than in the kidneys and liver! (6) Another argument in favour of this interpretation is that the plastic particles found were smaller than one micrometre, i.e. nanoparticles, which facilitates transport through the nerves. Not only were far fewer particles found in the liver, but they were also significantly larger. These are more likely to originate from food. The brains of dementia patients contained the most plastic. (6) In these patients, it is usually not the intestine that is diseased, but the olfactory brain. (77)
This brings the air we breathe into focus as a source of particles. (78) It offers a rich assortment of pollen, spores, exhaust fumes, soot and dust, especially from the abrasion of road markings and tyres. As elastomers, tyres contain not only plastics such as styrene-butadiene, but also natural latex. The latter can trigger allergies to fruit due to its chitinase content. (79)
Nylon reinforces the tyre, resins and phthalates serve as plasticisers, silicates and silanes provide better grip, and vulcanisation aids such as sulphur and zinc oxide are added, as well as strong antioxidants such as N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine to protect against ageing. (80,81) In the brains of deceased individuals, the content of styrene-butadiene rubber indicates that tyre abrasion has already occurred. (6)
When I was a child, spray trucks drove through the streets on hot days to bind the dust or remove it with sweepers. A classic case of prevention. But instead of keeping the streets clean, they now prefer to study diesel exhaust particles. To do this, researchers inject exhaust dust, i.e. microparticles, into the tail vein of pregnant mice. Weeks later, excited behavioural scientists test the male offspring. (82) What does this nonsensical animal cruelty teach us? Perhaps that preventive medicine specialists should not stick their tails into the exhaust pipe while the engine is running, so as not to develop further behavioural abnormalities?
The supply of particles via the nose is probably the ideal route into the brain. But we hear little about this, while experts on microplastics are everywhere. Perhaps this is because there are still no sniffing and smelling consultants, but legions of nutritionists who also have opinions on sophisticated topics.
When it's dusty
The term "microplastics" is just as useless in terms of health as "fine dust". It is not only the size, or smallness, that is important, but also the composition. Salty air at the seaside is considered healing, but the situation is quite different when it comes to fine metal dust in workshop air.
All materials are subject to decomposition. Everything is broken down in nature, right down to the finest dust and nanoparticles. Everything crumbles, whether it's old masonry, plastic or dead flies. Everything can enter our bodies at any time. We are surrounded by dust and inhale it with every breath. We swallow it with every meal. Whether it is road dust, house dust or flour dust. Whether it is bacteria, viruses or fungal spores.
Our bodies have been adapted to these gifts since time immemorial; they have to be able to deal with them. However, it can be assumed that the dust, micro- and nanoparticles have always concealed structures that our bodies cannot easily dispose of. Candida spores, for example, can cause fungaemia through persorption (83). But many people are afraid of "plastic". It sounds more threatening because it is "artificial" compared to "natural" wood dust. Unfortunately, hardwood dust is officially considered carcinogenic to the nose and throat. (84) A small amount of dust is therefore likely to inevitably find its way into the brain.
If you don't want plastic bags, you can also carry your shopping home in jute bags. What happens to jute when it is thrown away? Microjute – what else? Jute is "biodegradable", which is not usually an advantage over plastic. It is only suitable for a few applications and rots quickly. After extraction, it must be dipped in mineral oil in order to be processed. Only with a PVC coating can jute tolerate moisture. Due to its poor durability compared to plastic, it is a symbol of the throwaway society. The same applies to cotton bags: according to the Nature and Biodiversity Conservation Union (NABU), due to the environmental impact of their production, they must be used at least 100 times more often than plastic bags in order to achieve the same "climate balance".
Plastic also corrodes, which makes it difficult to identify as microplastic. (42) It just takes longer to weather than jute or cotton. All materials release micro- and then nanoparticles, some faster than others. There are no "eternal chemicals". To find out how microplastics, which are supposedly non-biodegradable, are broken down contrary to propaganda, see the "Brotzeit" article from 11 May 2018: "When the sea drowned in plastic".
What can be done?
Despite the measurement problems and doubts about the study results, here are a few tips for the anxious: if you want to avoid small particles in your brain, don't necessarily minimise plastic in the kitchen, but rather your consumption of grains and muesli, because nowhere else are there more absorbable particles. Even though starch is broken down after about six months, it causes embolisms in the brain. The main issue here is the amount that floods in with a single meal: 100 grams of starch in muesli is a completely different ball game than a few micrograms of microparticles in imported apples, most of which are excreted anyway.
Reasonable people avoid low-calorie products. They often contain fillers such as microcrystalline cellulose or proteins compressed into tiny pellets, which are often used in "low-fat" desserts. Microparticulated fat substitutes are also obtained from corn or potato starch. Here, too, persorption is obvious; for microcrystalline cellulose, it has been sufficiently proven in animal experiments. (85,86)
If you want to avoid unnecessary pollution of the environment with microplastics, only wash your clothes when they are dirty. It is not plastic bottles or plastic bags, but washing machines that are the biggest particle emitters. (87) These are mainly cotton fibres, followed by polyamide and polyester fibres. To heighten the perceived threat, cotton fibres were often counted as "microplastics" by "activists".
However, domestic laundry no longer has much to do with hygiene. On the contrary, modern washing machines usually only heat to 37 to 40°C, even when 60°C is selected. This provides the ideal conditions for germs to breed. Those who also save water impregnate their visually clean laundry with questionable germs. However, regular dusting and vacuuming is commendable, as it minimises the amount of microplastics in circulation.
The sensible person uses detergents and cleaning agents judiciously: in sewage treatment plants, detergent additives form glyphosate, as researchers in Tübingen recently demonstrated. In the fields, it is exactly the opposite. There, glyphosate is converted into a detergent called AMPA. The pollution of our rivers with glyphosate does not correlate with the activities of farmers, but with the discharges from sewage treatment plants. It depends on the activities of households that are enthusiastic about cleaning and washing, and less on the work of farmers producing our food. (91-93)
Textiles are impregnated with special plastic coatings to make them water-repellent, wrinkle-free, UV-resistant or "breathable". For example, the popular polytetrafluoroethylene generates millions of microparticles during washing. (88) On the other hand, treating polyamide fibres with substances such as glycidyl methacrylate could reduce the loss of microfibres during washing by 90%. 3-aminopropyltriethoxysilane achieves the same result with polyester fabrics (89,90).
It may sound paradoxical, but more chemistry means less microplastics. "Biodegradability" used to be a major problem. Chemistry created materials that are durable, do not tear or break, do not mould, and are not destroyed by moths or rodents. Even plastics are not made to last forever. Textiles made of polyester or nylon do break – but they last longer than untreated natural fibres "without chemicals".
Since durability stood in the way of the industry's sales targets, it equipped its goods with predetermined breaking points. Nylon stockings are indestructible in themselves. So the fibre was given weak points to cause runs. Today, many products are programmed to decay. The demand for biodegradability is intended to boost new purchases once again.
Digestion
There are several ways in which microparticles can enter the bloodstream and lymphatic system in the digestive tract: Firstly, through persorption: the particles penetrate via the intestinal villi. The constant renewal of the epithelium at their tip, where larger groups of cells detach, creates the entry point. There, the villi pump sucks in the particles. This process has been proven beyond doubt by electron microscope images of thin sections of the villi. The mucus-producing goblet cells, where the tissue is somewhat "looser", also play a part. Here, peristalsis kneads the particles into the tissue. (94-97)
The second entry point is Peyer's patches in the intestine, which use their M cells to specifically absorb larger particles. (98,99) This is how latex particles, ferritin, enzymes, bacteria, viruses and smaller parasites enter the body. M cells are an important part of the immune system. Through constant "sampling" in the intestine, the antigens of pathogens are passed on to special lymphocytes, which then produce specific antibodies. These are directed to the mammary glands, for example, to immunise the infant via breast milk. (97)
Most of the particles were found in the plaques and lymphatic tissue (GALT) of the large intestine in rats after they were fed titanium dioxide particles measuring 0.5 µm. From there, they entered the liver, spleen and lungs. (101) Humans also absorb titanium dioxide (in the nano range of 0.1 to 0.5 µm) through the intestine. (99) This is how the dye enters the bloodstream. (100) In an experiment with mice using colloidal gold particles (4 to 58 nm), however, persorption dominated. (102)
Needle-like objects use the direct route, which was first investigated using crushed rabbit hair. (1) They bore through the cell walls and thus enter the circulatory system. Now, rabbit skins are rarely eaten, but many plants such as nettles (e.g. in teas) have fine stinging hairs, hollow glass-like tubes that can pierce tissue.
A well-known example is asbestos fibres, which are both eaten and inhaled. As nanoparticles, they can also reach the brain. (64,69) The increased rate of brain tumours among asbestos workers confirms this. (104) The ban on wood flour as a separating agent in bakeries was also justified by the cancer risk posed by hardwood dust. (84) These particles also reach the brain. Inhalation is likely to be more important than ingestion. (105)
Not to mention the many cellulose fibres that are not only naturally present in fibre-rich products, but are even added to food as calorie-free fillers, such as microcrystalline cellulose (E 460) or wheat straw fibres. This is where the German expression "having straw in one's head" ["dumb as a rock"] finds a fitting interpretation.
The absorption of fats from milk fat is analogous. Butter is absorbed differently than cooking oil or margarine. Cooking oil is preferably absorbed after enzymatic breakdown into its components. Milk fat does not enter the bloodstream "digested", but in the form of fine fat droplets (chylomicrons). Absorption takes place not only through persorption, but primarily via the intercellular spaces. (94) Without this mechanism, newborns would hardly be able to use breast milk as food. The same applies to protein particles.
For information on microplastics in the sea, see the following articles on the EULE website:
=> Pollmers Mahlzeit: Plastikmüll - Putzkolonnen auf Abwegen Brotzeit 29. Juni 2019
=> Pollmers Mahlzeit: Mikroplastik überall - Ist die Welt noch zu retten? Pollmers Mahlzeit vom 11. Mai 2018
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English Editor: Josef Hueber
