Microplastics: Where They Come From and How to Avoid Them
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Twenty years ago, the word "microplastics" barely existed. Today, plastic particles have been found in drinking water, sea salt, honey, and the air inside our homes. They have also been found in human blood, lungs, placentas, arteries, and brains.
The mainstream response has largely been a shrug. There is not yet enough evidence, the reasoning goes, to say exactly what harm these particles cause.
As biohackers, we do not wait for perfect proof before removing an unnatural input from our environment. Human biology evolved over hundreds of thousands of years without synthetic polymers. Plastic particles accumulating in the tissues of an entire population is not a neutral development. The question is not whether to reduce exposure. It is how.
Here is the full picture.
What Microplastics Actually Are
Microplastics are plastic particles smaller than 5 mm. They come as fragments, fibres, films, and beads, and most are invisible to the naked eye. Below one micrometre, they are classified as nanoplastics — particles small enough to cross biological barriers that larger particles cannot.
They fall into two categories.
Primary microplastics are manufactured small on purpose. Examples include the microbeads once common in face scrubs and toothpaste, and the pellets used in industrial production. The EU began phasing out intentionally added microplastics in 2023, but older products and imported goods remain in circulation.
Secondary microplastics form when larger plastic items break down. Sunlight, heat, friction, washing, and ordinary wear and tear gradually fragment bottles, packaging, textiles, and tyres into smaller and smaller pieces. This is where the vast majority of microplastics come from, and it is why the problem keeps growing. Every piece of plastic ever produced is still out there somewhere, slowly breaking into smaller particles.
How Microplastics Get Into Your Body
Exposure happens mainly through two routes: what you eat and drink, and what you breathe.
Water. Microplastics are found in both tap and bottled water — and bottled water is often the worse of the two. Research published in PNAS in 2024, using advanced imaging, found an average of around 240,000 plastic particles per litre of bottled water. Roughly 90 percent of these were nanoplastics. Earlier methods had simply been unable to detect particles that small.
Food contact and heat. Plastic sheds particles most aggressively when it is heated, scratched, or worn. Microwaving food in plastic containers can release millions of microplastic and billions of nanoplastic particles from each square centimetre of the container. A study published in Environmental Science & Technology found that a single plastic tea bag steeped at brewing temperature released around 11.6 billion microplastic particles and 3.1 billion nanoplastic particles into one cup. Plastic cutting boards are another source, shedding particles with every cut — potentially tens of millions per year in a typical kitchen.
The rule is simple:
Plastic + heat + food → particles and chemicals in your meal.
Air and household dust. Synthetic textiles — polyester clothing, carpets, upholstery, fleece, and bedding — shed fibres constantly. These settle into household dust and remain suspended in indoor air, where they are inhaled. Most people spend the majority of their time indoors, which makes indoor air one of the most consistent exposure routes.
Personal care products. Some cosmetics, lotions, and cleaning products still contain synthetic polymers. Paint also releases plastic particles as it wears and flakes.
How much each person encounters depends on diet, home environment, occupation, and product choices. That variability is the good news: it means exposure is, to a meaningful degree, under your control.
It Is Not Only the Particles
Plastic is rarely just plastic. Most products contain chemical additives that give them flexibility, durability, colour, or heat resistance. These include bisphenols such as BPA and phthalates.
Many of these additives are known endocrine disruptors — compounds that interfere with the body's hormone signalling. They are not chemically bound to the plastic, so they leach out over time, and faster with heat, fat, and acidity.
This means microplastics act as carriers. The particle itself may cause physical irritation and inflammation, while the chemicals it brings with it act on the hormonal system. Both matter.
Six Health Concerns Under Investigation
Much of the research here is early. Many studies show associations rather than proven cause and effect, and the field is moving quickly. But the pattern emerging across multiple organ systems is consistent — and it is not reassuring.
1. Inflammation and oxidative stress
Oxidative stress occurs when reactive oxygen species overwhelm the body's antioxidant defences, damaging proteins, fats, and DNA. Research published in Science of the Total Environment found that PTFE microplastics — the material used in non-stick coatings — increased oxidative stress and inflammatory signalling in human lung and immune cells.
Cell studies do not perfectly reflect real-world exposure. But chronic, low-grade inflammation is the common thread running through almost every modern chronic disease. Any input that adds to it deserves attention.
2. Gut and microbiome disruption
Swallowed microplastics pass through the entire digestive tract, coming into direct contact with the intestinal lining and the gut microbiome. Effects under investigation include shifts in gut bacteria, irritation of intestinal cells, and weakening of the intestinal barrier. A compromised gut barrier is a known gateway to systemic inflammation.
3. Cardiovascular risk
This is where the evidence is most striking. A study published in The New England Journal of Medicine examined arterial plaque removed from patients during carotid artery surgery. More than half had detectable microplastics and nanoplastics embedded in their plaque. Over roughly three years of follow-up, those patients had around four and a half times the risk of heart attack, stroke, or death from any cause compared with patients whose plaque contained no detectable plastic.
Association is not proof of causation. But plastic particles physically embedded in arterial plaque, combined with a markedly higher rate of cardiovascular events, is a signal that should not be dismissed.
4. Hormonal and reproductive effects
A study published in Ecotoxicology and Environmental Safety found microplastics in the follicular fluid surrounding developing eggs in 14 of 18 women undergoing fertility treatment. Higher microplastic levels correlated with higher follicle-stimulating hormone (FSH), a key regulator of ovarian function.
Combined with the known endocrine-disrupting effects of plastic additives, this makes reproductive and hormonal health one of the most important areas to watch — and one of the strongest reasons for anyone planning a family to reduce exposure now.
5. Lung and respiratory effects
Inhaled microplastics can travel deep into the lungs, where the smallest particles may be difficult for the body to clear. Repeated exposure means ongoing accumulation. Researchers are investigating links to airway irritation, changes in lung tissue, and reduced lung function. People working with synthetic textiles or plastic dust face considerably higher exposure than the general population.
6. Brain and nervous system
Research published in Nature Medicine found higher concentrations of microplastics and nanoplastics in human brain tissue than in liver or kidney samples. Concentrations in brain samples from 2024 were significantly higher than in samples from 2016. Brains from people diagnosed with dementia contained even greater amounts.
The study does not show that microplastics cause dementia. But it does show that plastic is crossing into the most protected organ in the body, and that the amount is rising.
Can the Body Clear Microplastics?
Partly. According to the World Health Organization, more than 90 percent of ingested microplastics are likely to pass through the digestive tract and be excreted. Particles larger than 150 micrometres are considered especially unlikely to cross the intestinal wall.
The problem lies at the smaller end of the scale. Smaller microplastics can be absorbed to a limited degree, and nanoplastics appear able to cross into the bloodstream and tissues far more readily. These are the particles turning up in arteries and brains — and they are also the hardest to measure, which means the evidence is still catching up.
There is currently no proven protocol for removing microplastics already lodged in tissue. We are not interested in "detox" products that sound convincing and do nothing. The intervention that works is the obvious one: reduce what goes in.
How to Reduce Your Exposure
You cannot eliminate microplastic exposure entirely. They are in the environment now. But the largest sources in daily life are concentrated in a few places — the kitchen, your drinking water, and your home environment — and the changes needed there are simple.
In the kitchen
- Never heat food in plastic. Microwave and reheat in glass or ceramic.
- Store food in glass or stainless steel containers, especially anything warm, fatty, or acidic.
- Replace plastic cutting boards with wood.
- Cook with cast iron, stainless steel, or carbon steel instead of non-stick coatings.
- Replace scratched, worn, or cloudy plastic kitchenware.
- Use loose-leaf tea or certified plastic-free tea bags.
- Reduce food bought in plastic packaging, particularly ready meals and takeaway containers.
Water
- Avoid bottled water wherever possible.
- Drink from glass or stainless steel bottles and cups.
- Use a quality water filter, such as reverse osmosis or a high-grade carbon block system, if your tap water source is a concern.
In Iceland, we are fortunate to have some of the cleanest tap water in the world. It makes no sense to give that advantage away by drinking from plastic bottles.
At home
- Choose natural fibres — cotton, linen, wool, silk, hemp — for clothing, bedding, and towels where you can.
- Vacuum regularly with a HEPA-filtered vacuum to reduce fibre-laden dust.
- Use natural-fibre cleaning cloths instead of synthetic microfibre.
- Wash synthetic clothing at lower temperatures and on gentler cycles to reduce fibre shedding.
- Ventilate your home regularly.
Personal care
Simplify. The fewer synthetic products you apply to your skin, the fewer synthetic compounds your body has to deal with. Natural, minimally processed alternatives exist for almost every category. Read ingredient lists the way you read food labels.
The Biohackers Corner Perspective
Microplastics are a textbook example of a modern input the human body was never designed to handle. They did not exist in the ancestral environment. They are now present in nearly every human tissue that has been tested, and the concentrations are rising.
The research is still young. Much of it shows associations rather than definitive causes. But waiting for certainty means waiting decades while exposure accumulates — and the changes that reduce exposure cost almost nothing.
This is the same principle we apply to food. Replace the industrial with the natural. Choose materials your biology recognises. Remove the inputs that do not belong.
Glass instead of plastic. Steel instead of non-stick. Wood instead of polymer. Wool and cotton instead of polyester. Tap and filtered water instead of bottles.
You cannot control the whole environment. You can control your kitchen.
Start there.
