Microplastics Exposure: Sources, Risks & Reduction

You cannot shop your way to zero exposure, but you can find your largest sources and act on them. Welden narrows the measurement problem to a defined particle-size window by using published studies and your reported habits to estimate annual exposure to microplastic particles between 10 and 100 micrometers.

What microplastics are

Microplastics are plastic particles smaller than 5 millimeters. Particles below 1 micrometer are often called nanoplastics, but keep in mind that definitions and measurement conventions vary. Microplastics can form as larger items break down, or be released directly from synthetic textiles, tires, packaging, coatings, and plastic household products.

They have been found in nearly every environment we occupy (air, water, food, and household dust) and have been detected in human tissues, including blood,⁶ the placenta and reproductive tract,¹³ and kidney and brain tissue.⁹ Those findings do not combine into a simple personal dose: different studies capture different polymers, different particle sizes, use different contamination controls, and report results as counts, mass, or concentration.

Why the measurement limit matters A method that detects particles down to a few hundred nanometers can count vastly more particles than a method that stops at 20 micrometers. Both may be valid for what each method can see, but they should not be presented as directly comparable totals. This is also why articles about microplastics can report wildly different exposure numbers; they are not comparing like with like.

How much does a person take in?

There is no agreed annual total, but a wide array of studies lets us begin to form an estimate.

A widely cited 2019 analysis by Cox and colleagues estimated approximately 39,000–52,000 particles per year from the food and drinks it evaluated. When inhalation was included, the estimate rose to approximately 74,000–121,000 particles per year, depending on age and sex. The analysis covered only about 15% of Americans’ caloric intake and described its estimates as underestimates.²

A 2024 study using a more sensitive imaging technique reported an average of about 240,000 micro- and nanoplastic particles per liter across samples from three bottled-water brands, with roughly 90% classified as nanoplastics.⁴ It was an important measurement advance, which shed some light on the breadth of the problem with plastics even smaller than what’s considered “microplastics,” but it is not a universal count for every bottle.

How Welden quantifies exposure

This article reports the Welden Exposure Engine’s annual particle-count ledger normalized to the 10–100 µm size range. (How big is that? Take a millimeter and divide it by ten; that is 100 microns, or µm.) That count is not the entire microplastics score: the separate score is a composite that also incorporates an internal cutting-board shedding mass component and a fine-air count component. Welden maps reported habits to published measurement studies and combines relevant pathways into a modeled estimate. It is not a direct laboratory measurement of particles retained in the body. Most ingested particles pass through. Regulatory reviews indicate that particles larger than about 150 µm are typically not absorbed, that absorption of smaller particles is limited, and that only the smallest (roughly 1.5 µm and below) may penetrate deeply into tissues such as the liver and brain.¹⁰ Read the broader Welden methodology.

This is for informational purposes only. It is not to be used for diagnosis or any medical purpose. Consult your primary healthcare provider for any questions about contaminant exposures.

The exposure routes research can support

Particles in air can be inhaled; particles in food and drink can be ingested. Welden groups its modeled 10–100 µm particle count into three categories (breathing, drinking, and eating), then traces each back to the individual habits and measured-source pathways that contribute to it.

**Current Welden Exposure Engine output.** Annualized from one verified engine run using the workbook’s default adult reference profile with no user overrides. This reports the 10–100 µm count ledger, not the separate composite microplastics score.

Plastic cutting boards: measured shedding, limited outcome evidence

A 2023 laboratory study measured polyethylene and polypropylene particles released while chopping on plastic boards. Its modeled annual estimates varied substantially with board material, cutting style, and age of the board.³ Chopping tends to shed comparatively large fragments, up to roughly a millimeter. Particles that large are generally too big to be absorbed by the body, but reviews note that non-absorbed particles can still provoke local inflammation in the gut, and laboratory studies report inflammatory and barrier effects from smaller particles.¹⁰¹¹ Using a non-plastic cutting surface avoids the plastic-board shedding pathway measured in that study.

Are microplastics harmful to health?

The scope of everyday exposure is coming into focus, but the science on precise health impacts is still early.

Detecting a particle, or estimating exposure to it, is not the same as showing it causes harm, a distinction worth keeping in mind as the human evidence develops.

A 2024 observational study found that people with micro- and nanoplastics detected in removed carotid plaque had a higher rate of heart attack, stroke, or death during follow-up.⁷ While it showed an association in a specific surgical population, it did not establish that the particles caused those outcomes.

A 2025 Nature Medicine study led by University of New Mexico researchers analyzed postmortem liver, kidney, and brain samples collected in 2016 and 2024, and reported that micro- and nanoplastic concentration in brain tissue rose from 3,345 to 4,917 micrograms per gram from 2016 to 2024, about 47%.⁹ Two cautions matter. The authors noted the rise tracked the growth of plastic waste in the environment, but that is context, not proof that brain levels climb in step with plastic production. And the absolute concentrations are contested: independent researchers have questioned whether the method used can reliably separate plastic from naturally occurring lipids and other biomolecules, which could overstate the measured mass, so these figures are best read as preliminary.

Separately, laboratory and animal studies have linked microplastic and nanoplastic exposure to intestinal inflammation, barrier dysfunction, and oxidative stress, though whether these effects occur at typical human exposures is not established.¹¹¹² The World Health Organization’s broad review concluded that major uncertainties remain in exposure measurement and health-risk assessment.¹ As a reminder, Welden describes exposure and evidence strength, not diagnosis or personal medical risk. If you are concerned about impacts to your health, discuss them with your primary healthcare provider.

What we will not tell you

We will not sell you a “microplastics in your blood” test. There is no validated consumer test that can turn an at-home sample into a clinically interpretable body-burden score, or compare it with an accepted population reference range. Some services claim to offer one, but these tests lack intra-sample stability, i.e., running the same sample twice can produce very different results. If you want to gauge your body burden of these chemicals, a urine plasticizer test that measures phthalate and BPA metabolites is a more validated option.

Welden also does not claim that a household swap will make you healthier. The clinical benefit of reducing plastic exposure has not been established. If you do wish to reduce your exposure, the steps below are practical, low-regret ways to reduce avoidable plastic contact.

Practical ways to reduce avoidable exposure

The best order depends on what you use most often, what your local water guidance recommends, and what changes you can maintain.

Reduce repeated single-use beverage packaging

Where local water quality permits, use tap water and a durable glass or stainless-steel bottle. Choose a filter for a defined local contaminant need, not on the assumption that every filter reduces microplastics or cannot shed material itself.

Drinking 130,000modeled / year

Avoid heating food in plastic

Transfer food to glass or ceramic before microwaving or adding very hot contents. Experimental work has found greater particle release under microwave heating than under refrigeration or room-temperature storage.⁸

Eating 1,055modeled / year

Use a non-plastic cutting surface

A properly maintained wood board avoids the polyethylene or polypropylene shedding measured during chopping on plastic boards. Follow food-safety guidance for cleaning, drying, and replacing any damaged board.

Eating 237,380modeled / year

Manage indoor dust for broader air-quality reasons

Ventilation where outdoor conditions allow, damp dusting, and a well-maintained HEPA vacuum can reduce general indoor particulate matter. While a higher count, these airborne particles tend to be small in scale relative to other microplastics. Microplastic-specific personal dose reduction has not been quantified well enough to promise a percentage.

Breathing 1,412,270modeled / year

Product disclosure: Some Welden guides may link to products that address these pathways. Welden may earn an affiliate or commission fee on purchases. Product-specific pages disclose relationships before purchase links.

Trade the headline for your own number

Answer a short set of questions to receive a personalized annual 10–100 µm particle-count estimate, the separate composite microplastics score, and a source-by-source breakdown with practical next steps.

Calculate your exposure estimate Modeled from published research and your reported habits. Not a laboratory test or medical diagnosis.

Frequently asked questions

What are the main routes of microplastic exposure?

The two broad routes are inhalation and ingestion. Indoor air and dust, drinking water, food, and food-contact materials can contribute. Current evidence does not support one universal percentage breakdown for everyone.

How many microplastics does a person consume per year?

There is no agreed universal total. For the Welden Exposure Engine’s default adult reference profile, its 10–100 µm count ledger produces about 3 million modeled particles per year: roughly 1.4 million from breathing, 1.2 million from drinking, and 0.4 million from eating. This is a modeled reference profile, not a measured national average or a body-burden result.

Do plastic cutting boards release microplastics?

Yes. A 2023 laboratory study measured polyethylene and polypropylene particle release during chopping. Release varied with material and cutting conditions. The study did not establish a resulting human health effect.

Is filtered tap water always lower in microplastics?

No universal claim is possible. Results depend on the incoming water, treatment process, filter material, maintenance, and detection method. Choose a filter for contaminants documented in your local water and follow its replacement instructions.

Can I test how much microplastic is in my body?

Research laboratories can measure some polymers in some biological samples, but there is no validated consumer test with an accepted clinical reference range or proven interpretation for personal health decisions.

Are microplastics proven to cause disease?

Not in the way required to make a personal diagnosis or treatment claim. Human observational evidence is emerging, while much mechanistic evidence comes from cell and animal studies. Association, detection, and causation should be kept distinct.

Sources and research standards

World Health Organization (2022). Dietary and inhalation exposure to nano- and microplastic particles and potential implications for human health. WHO report.
Cox, K. D. et al. (2019). Human Consumption of Microplastics. Environmental Science & Technology, 53(12), 7068–7074. doi:10.1021/acs.est.9b01517.
Yadav, H. et al. (2023). Cutting Boards: An Overlooked Source of Microplastics in Human Food? Environmental Science & Technology, 57(22), 8225–8235. doi:10.1021/acs.est.3c00924.
Qian, N. et al. (2024). Rapid single-particle chemical imaging of nanoplastics by SRS microscopy. PNAS, 121(3). doi:10.1073/pnas.2300582121.
Vianello, A. et al. (2019). Simulating human exposure to indoor airborne microplastics using a Breathing Thermal Manikin. Scientific Reports, 9, 8670. doi:10.1038/s41598-019-45054-w.
Leslie, H. A. et al. (2022). Discovery and quantification of plastic particle pollution in human blood. Environment International, 163, 107199. doi:10.1016/j.envint.2022.107199.
Marfella, R. et al. (2024). Microplastics and Nanoplastics in Atheromas and Cardiovascular Events. New England Journal of Medicine, 390, 900–910. doi:10.1056/NEJMoa2309822.
Hussain, K. A. et al. (2023). Assessing the Release of Microplastics and Nanoplastics from Plastic Containers and Reusable Food Pouches. PubMed record.
Nihart, A. J. et al. (2025). Bioaccumulation of microplastics in decedent human brains. Nature Medicine, 31, 1114–1119. doi:10.1038/s41591-024-03453-1.
EFSA Panel on Contaminants in the Food Chain (2016). Presence of microplastics and nanoplastics in food, with particular focus on seafood. EFSA Journal, 14(6), 4501. doi:10.2903/j.efsa.2016.4501.
Huang, Z. et al. (2021). Polystyrene micro- and nanoplastics jointly induce intestinal barrier dysfunction by ROS-mediated epithelial cell apoptosis. Particle and Fibre Toxicology, 18, 20. doi:10.1186/s12989-021-00414-1.
Lee, Y. et al. (2023). Health Effects of Microplastic Exposures: Current Issues and Perspectives in South Korea. Yonsei Medical Journal, 64(5), 301–308. doi:10.3349/ymj.2023.0048.
Ragusa, A. et al. (2021). Plasticenta: First evidence of microplastics in human placenta. Environment International, 146, 106274. doi:10.1016/j.envint.2020.106274.