What Do Microplastics Actually Do to Your Body?

For years, microplastics were treated as an environmental problem. Something that happened to fish. Something out there in the ocean.

They're in you too. Microplastics have now been found in human blood, lungs, liver, placentas and breast milk. The science on what they do once they're there is still developing, but what's emerging isn't good.

What are microplastics?

Microplastics are small plastic particles, under 5 millimetres. Some are manufactured that size (like microbeads in cosmetics, now largely banned). Most are fragments that break off from larger plastic products as they degrade, or fibres shed from synthetic textiles during washing and wear.

Nanoplastics are the smaller subset, under 1 micrometre, small enough to cross cell membranes. These are the ones that concern researchers most.

How microplastics get into your body

Three main routes:

• Food and water. Microplastics have been found in bottled water, tap water, seafood, table salt and beer. If you eat or drink, you ingest microplastics.
• Air. Synthetic fibres shed from clothing and furnishings become airborne and get inhaled. They've been found in lung tissue.
• Skin contact. Dermal absorption is less understood but is an active area of research, particularly for clothing worn directly against the skin.

The average person is estimated to ingest around 5 grams of plastic per week, roughly the weight of a credit card. That's a rough estimate, and the actual figure varies by source and lifestyle, but the direction is consistent: exposure is significant and ongoing.

What do microplastics actually do once they're inside you?

This is where science is still building its case, but the signals aren't reassuring.

Inflammation. Studies in lab settings have shown that microplastic particles trigger inflammatory responses in human cells. Chronic low-grade inflammation is associated with a wide range of health conditions.

Endocrine disruption. Many plastics contain chemical additives (plasticisers, stabilisers, flame retardants) that can interfere with the body's hormonal system. BPA is the most well-known, but there are hundreds of others. Some of these chemicals leach out of plastic particles inside the body.

Cardiovascular risk. A 2024 study published in the New England Journal of Medicine found microplastics and nanoplastics in the fatty plaques of patients with carotid artery disease. Patients with detectable plastics in their arteries had a significantly higher risk of heart attack, stroke and death over a 34-month follow-up period.

Reproductive effects. Microplastics have been found in human testes, ovaries and placentas. What this means for fertility and foetal development is still being studied.

It's important to be clear: this science is not settled. Establishing cause and effect in humans is difficult, and researchers are still building the evidence base. But the precautionary principle applies, and the trend in the research is not moving in a reassuring direction.

Clothing is a significant exposure route

Synthetic clothing (polyester, nylon, acrylic) sheds plastic fibres constantly, during wear, during washing and as it sits in your wardrobe. A single wash of a synthetic garment can release hundreds of thousands of microfibres into wastewater. Many pass through treatment plants and end up in waterways.

But there's also direct skin exposure. Wearing synthetic fabric against your skin all day means prolonged contact with plastic fibres. It's not the only exposure route, but it's one of the most consistent and easiest to do something about.

Switching to natural fibres (merino wool, cotton, linen, hemp) eliminates that exposure entirely. If you want to know which natural-fibre options are worth considering for men's shorts, we covered them in our guide to the best plastic-free men's shorts in Australia.

What can you actually do about it?

We covered this in detail in our guide to reducing microplastics, but the practical steps include: filtering your drinking water, choosing natural fibres over synthetics, using a microplastic filter on your washing machine, and reducing single-use plastic in food and drink.

You can't eliminate all exposure. But you can reduce it meaningfully, especially in the areas you control most directly, like what you wear.

FAQs

Are microplastics harmful to humans?

Emerging research suggests yes, but the full picture is still being established. Microplastics have been found in human organs and blood, and lab studies show inflammatory and endocrine-disrupting effects. A 2024 study linked microplastics in arteries to increased cardiovascular risk.

How do microplastics get into the human body?

Through food and water (the most significant route), through inhaling airborne fibres, and through skin contact with synthetic materials. Microplastics have been detected in blood, lungs, liver, placenta and breast milk.

How much plastic does the average person consume?

Estimates vary, but roughly 5 grams per week is a commonly cited figure based on a 2019 WWF/University of Newcastle study. This includes plastic in water, food and air.

Can clothing be a source of microplastic exposure?

Yes. Synthetic textiles shed plastic microfibres during wear, washing and simply over time. Wearing plastic-based fabric directly against your skin is a consistent exposure route. Natural fibres like merino wool and cotton don't shed plastic.

Sources

• Marfella et al. (2024), Microplastics and Nanoplastics in Atheromas and Cardiovascular Events, New England Journal of Medicine
• Senathirajah et al. (2021), Estimation of the mass of microplastics ingested, Journal of Hazardous Materials
• Ragusa et al. (2021), Plasticenta: First evidence of microplastics in human placenta, Environment International
• Leslie et al. (2022), Discovery and quantification of plastic particle pollution in human blood, Environment International

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