How dangerous are microplastics?

Key Takeaways

• Microplastics and nanoplastics are abundant in drinking water, soil, food, and even the air
• The effects of microplastics on human health are not fully understood, but they have been convincingly linked to a wide range of respiratory issues, digestive issues, fertility concerns, neurological problems, and a variety of cancers
• Avoiding single use plastic products and non-natural textiles can help reduce your personal exposure to microplastics

What are microplastics (and nanoplastics)? 

As the name implies, microplastics are tiny plastic particles, less than 5 millimeters in diameter^[1]. Nanoplastics, a subgroup of microplastics, are defined as being smaller than 1 micron (to give you an idea of the size of these items, 5 millimeters is about the width of a pencil eraser; a single micrometer is about the size of a particle of tobacco smoke). Microplastics can be formed from the breakdown of larger plastics, or as a primary source (until 2015, when they were banned in the US, microplastic beads were used regularly in cosmetic and personal care products^[2]). Nanoplastics are formed exclusively from the breakdown of larger plastics, including microplastics. 

While true microplastics have wide-ranging environmental and health considerations, nanoplastics are even more concerning from a personal health standpoint. Their size allows them to interact with all parts of the human body in ways we’re only just beginning to realize. 

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Paths of exposure 

Micro- and nanoplastics (MNPs) are pervasive–they have been found in every corner of the globe, including remote regions of the Arctic^[3] and in sea creatures dwelling deep in the Mariana Trench^[4]. They’ve also been found in nearly every type of human tissue, and have been seen to pass through the placenta^[5] and cross the blood-brain barrier.^[6]

Humans are exposed to nanoplastics in many ways: 

1. Ingestion
   Thought to be the primary path of MNP exposure, ingestion of MNPs is common to the point of being unavoidable. MNPs are present in meat, seafood, and dairy, and are absorbed into plants^[7] via tiny cracks in their roots. Even minimally processed or raw foods are likely to contain some amount of MNPs.
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   MNPs have also been found widely in both tap and bottled water^[8], including water packaged in non-plastic materials–interestingly, concentrations were similar in bottled waters regardless of the packaging. Food packaging is also a regular source of contamination by MNPs, particularly when the packaging is heated as with some tea bags and microwaveable foods.
   
   It’s estimated that globally, humans consume as much as 5 grams of plastic weekly from what they eat and drink. For reference, that’s about the weight of a credit card.
   
   
2. Airborne particles^[9]
   MNPs have been detected in both indoor and outdoor air, and are subject to the same conditions as all other airborne pollutants–weather and airflow play a large role in how concentrated they become, as does the immediate environment. They’re far more common in urban settings than rural ones, for example, and are similarly concentrated around industrial areas.
   
   In indoor air, synthetic textiles are thought to be a major contributor to MNP accumulation. Polyester, nylon, spandex, fleece, rayon, acrylic, polypropylene (often used in moisture-wicking fabrics) and many modern velvets all contain plastics that can easily become airborne through regular wear and tear.^[10]
   
   
3. Skin contact
   MNPs in soil and water have been shown to permeate the skin barrier^[11], possibly more easily when the skin is wet or sweaty^[12]. It’s believed that the particles enter through the pores; due to the variance in pore size from individual to individual, the amount of permeation can vary significantly. 

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Health risks from microplastics

As MNPs break down to smaller and smaller sizes, they can easily enter any organ in the human body.^[13] Particles smaller than 10 microns have been shown to cross the blood-brain barrier. The plastics may take hundreds of years to fully degrade, meaning the chemicals they contain–and any health effects those chemicals might cause–can affect the human tissues where they accumulate. 

1. Lung issues
   Studies analyzing accumulation of MNPs in humans show the lungs contain the highest concentrations of the particles. Studies (usually in occupational settings with high exposure) have tied MNPs to lung cancer, pneumonitis (inflammation and swelling of the lung tissue), pleural effusion (fluid buildup between the lung and chest wall), bronchiolitis, and irritation of the respiratory tract without other specific diagnoses (such as coughing and wheezing).
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2. Digestive problems
   Colorectal cancer, IBD, microbiome disruption, and metabolic disorders such as type 2 diabetes have all been linked to accumulation of MNPs, with the severity of IBD tied directly to the amount of MNPs detected in fecal samples. 
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3. Endocrine problems and fertility concerns
   Many of the chemicals used to create the plastics that eventually degrade into MNPs are known endocrine disruptors (such as bisphenol A, or BPA^[14]), which means they’re known to affect hormones that play a role in everything from metabolism to fertility. Decreased fertility and low birth weight are some of the effects that seem to be tied to MNP exposure.
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4. Neurological issues
   Though more research is needed into the mechanisms tying MNP exposure to neurological issues, the particles have been implicated in neurotoxic effects–such as fatigue, dizziness, and headache–in dementia, and in degenerative neurological conditions. 
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5. Additional concerns and cancer risks
   MNPs have been shown to accumulate in nearly every human organ and system, which makes it unsurprising that a range of additional health concerns have been tied to the particles. Leukemia, lymphohematopoietic cancers, bladder cancer, and pancreatic cancer have all been convincingly tied to MNP exposure. Heart 5disease risk^[15], non-alcoholic fatty liver disease (NAFLD), allergic reactions of the skin, and contact dermatitis have also been tied to exposure. NAFLD and ongoing inflammation are themselves both risk factors for cancer development.^[16] 

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Ways to reduce exposure 

Given the global prevalence of MNPs in soil, food, and water, it’s impossible to entirely eliminate one’s exposure to the particles. Thoughtful choices, however, can lower both your overall exposure and specific exposure to chemicals in MNPs that have been convincingly tied to harmful outcomes. 

1. Eliminate single use plastics
   Eating food or drinking beverages from plastic containers has been shown to transfer MNPs to test subjects. Heating food in plastic microwave containers and washing plastic containers in the dishwasher can cause them to release more MNPs^[17], and while single use plastics on grocery items may prolong shelf life, they’ve been shown to shed into food. Tea is a particularly concerning source of MNP exposure^[18]–if you’re not certain your teabag is plastic free, consider opting for loose leaf tea instead. Whenever possible, opt for glass or ceramic containers for food storage and transport. It may be less convenient, but it also carries none of the risk of MNP transfer. 
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2. Dietary considerations^[19]
   While most foods contain some amount of MNPs, some foods accumulate much higher levels. A February 2024 study found MNPs in every protein it tested, but the highest levels have been found in seafoods, particularly shellfish. Apples and carrots contain surprisingly high levels of the particles, as does salt, particularly Himalayan sea salt. Sugar, rice, and bottled water were also found to contain high levels of MNPs. Trying to eliminate plastic intake via diet would be an impossible task, but if you’re particularly concerned about exposure, some small changes–like shifting your protein choices and eliminating bottled water–could have an impact. 
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3. Filter your water
   As with PFAs (“forever chemicals”), a high-quality water filter can significantly reduce the amount of MNPs you consume. The Environmental Working Group and the National Sanitation Foundation are two independent groups that test and certify water filters (among other things) for effectiveness and safety. 
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4. Rethink food preparation
   Carefully choosing low-MNP foods and transporting them without plastic will only do so much if your preparation techniques are adding MNPs back into the food you eat. Plastic cutting boards can contaminate food you prepare on them^[20], and formula prepared in plastic bottles contains higher concentrations of the particles. 
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5. Choose natural textiles
   Fabrics–whether in clothing, bedding, or upholstery for furniture–can release MNPs^[21] that are easily inhaled. Choosing non-synthetic textiles when possible–linen, cotton, silk, wool, bamboo–can significantly reduce this exposure path. Tencel/lyocell is another good option; while technically synthetic, it’s created from wood pulp, and contains no MNPs. 
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6. Vacuum^[22]
   ‍Sometimes common-sense interventions work; a study on indoor MNP levels showed vacuuming regularly could significantly reduce concentration of the particles in the home.

More study is needed to understand the ways micro- and nanoplastics affect human health, but early evidence indicates it would be wise to try to limit your exposure.