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Microplastics in food: What you need to know

When it comes to microplastics on our dinner plates, there’s a lot we still don’t know.

By

Maddy Lauria

It’s no great secret that there are traces of bugs and other unpleasantries in processed foods like coffee and chocolate. But much of what we eat and drink also contains tiny bits of plastic. Microscopic chips fall into drinks from bottle caps, and we unknowingly sprinkle particles on our plates when we add a pinch of sea salt. 

Microplastics in food trace back to nearly every corner of the world—from the soil our grub grows in, to the waterways where we catch fish, to the packaging of our favorite cookies. Our dinner plates and pantries, it turns out, are pretty polluted.

What are microplastics?

Microplastics are exactly as they sound: Tiny pieces of plastic. Technically, they’re bits smaller than 5 millimeters (about the width of a pencil’s eraser). Some microplastics start out that way, such as the microbeads found in cosmetics and cleaning products. But most microplastics are pieces of what were once much bigger plastics (known as macroplastics): bottles, bags, toys, and pretty much any and every consumer item made of plastic. Those finished products also often contain additives that easily spread when plastics break down; pigments and flame retardants, which are often made of toxic chemicals, have suspected links to serious health concerns, including cancer, reproductive dysfunction, and long-term health problems like cardiovascular disease.1

How much microplastic do we consume?

In 2019, findings published in the journal Environmental Science & Technology estimated that people ingest 39,000 to 52,000 particles of microplastics per year just from food.2 However, the exact number still remains a hot debate. Dutch researchers published a meta-analysis (that is, a review of several studies) in 2023 warning that there are few scientific papers estimating human ingestion of microplastics, and that limited data is very difficult to compare.3

While the number may be up in the air, consumption of any microplastics has medical and scientific experts concerned about how those plastic pieces may be affecting human health. Researchers are particularly interested in the particles’ influence on the gut microbiome, which plays a pivotal role in many different health outcomes.4

How do microplastics get into food?

Because plastics are such an integral part of our everyday lives, that means they also play a huge role in our food systems, from farming and fishing equipment to packaging. You likely have plastic equipment in your kitchen—utensils, storage containers—right alongside food items, such as meat, vegetables, and milk. All of these products, particularly their packaging, are susceptible to degrading into microplastic particles that can ultimately find their way into our food.

Plastics continue to break down over the years, decades, and centuries—especially in aquatic environments. That means commercially important seafood species, like anchovies, are susceptible to ingesting microplastics as they munch on plankton.

Here’s how those plastics can end up everywhere from the water supply to the kitchen sink:

Water contamination

Remnants of almost everything on land will eventually end up in the water. Storms and rain wash pollutants off of fields, yards, and roadways and into nearby creeks, rivers and oceans. That includes macro- and microplastic. At least 19 to 23 million metric tons of plastic waste reaches waterways around the world annually as of 2016, according to a 2020 study published in the journal Science.5

Plastics continue to break down over the years, decades, and centuries as they are exposed to natural elements such as UV rays—especially in aquatic environments. That means commercially important seafood species, like anchovies, are susceptible to ingesting microplastics as they munch on plankton.6 Microplastics also can turn up in shellfish such as mussels, which filter water in order to eat. Contamination from plastics and related chemicals may be directly harming some of these animals, causing changes to their cells and triggering inflammatory responses.7

Farming

A common fertilization method might be a major culprit for microplastics in our food. “Sewage sludge” is the mud-like, nutrient-rich substance created from treating wastewater from residential, municipal, and industrial sewer systems—and an attractive fertilizer option for some farming operations around the world. But, fertilizing with waste comes with significant risks. A 2022 analysis by the nonprofit Environmental Working Group found that the application of sewage sludge has contaminated nearly 20 million acres of American farmland with the toxic “forever” chemicals known as PFAS that are found in many plastic products. 

Experts also have found that this sludge can contain high levels of microplastics, which can reach other areas of land that weren’t treated with sludge.8 However, other research cautions that it “is largely unknown” where microplastics contamination ultimately ends up.9 Another study even found that farming equipment itself, which is often made of plastics like PVC and polyethylene, could be responsible for contaminating farm fields with microplastics.10

Production and processing

Equipment and even the water used to produce and process foods can lead to microplastics contamination—especially when it comes to pre-cooked or ready-made meals.11 But don’t forget that the phrase “processed foods” also applies to a lot of what you drink: multiple studies have found that beverages, such as beer and milk, contain microplastics.12 

Packaging

Up to 40% of all plastics produced globally are for single-use, typically for food packaging.13 All that waste has to end up somewhere, and oftentimes that’s in our environment or bodies. Those packages can release microplastics in a variety of ways. Plastic tea bags, for instance, release the particles when they steep in hot water.14 Opening plastic bags and bottles15 and microwaving food in plastic containers16 are also common culprits of microplastic contanimation.  

Microplastics in the food chain

All forms of wildlife can ingest plastics, especially marine life such as fish, which can often mistake microplastics for food. Microplastics can move up through the food chain—for example, if a fish ingests some, the bird or person that eats that fish also risks eating the microplastics. In some cases, both the plastics and additive chemicals can bioaccumulate, or collect in the body faster than they can be disposed of. However, a review of more than 1,000 studies found that microplastics don’t biomagnify, or increase levels of concentration, as they move up the food chain.17

Which foods contain microplastics?

Nearly everything we consume likely contains some level of microplastics. This is especially true if it’s been processed or packaged. But studies indicate that seafood and beverages may be the worst culprits.

Microplastics in seafood

Microplastics have been found in a wide variety of fish species, including northern whiting, grouper, seabass, haddock, squid, mackerel, and canned fish including tuna and sardines. Shellfish aren’t safe either: Shrimp, crabs, scallops, clams, oysters and mussels all have been found to contain microplastics.18 

Microplastics in water and other beverages

Both tap water and bottled water have been found to include microplastics, including drinking water that comes from a “high-performance drinking water treatment plant.” According to the World Health Organization, microplastics can reach tap water from many avenues, including when they run off land and reach waterways that provide drinking water and sneak through treatment processes.19 They also come from rain or snow reaching those water sources (this is also known as atmospheric deposition).

One 2018 study found that 93% of bottles sampled (from 11 different companies and purchased from nine different countries) showed some sign of microplastic contamination.

In bottled water, packaging is the most likely source of the contamination. One 2018 study found that 93% of bottles sampled (from 11 different companies and purchased from nine different countries) showed some sign of microplastic contamination.20 Many existing water filters can help reduce microplastics coming from the tap, including those that use activated carbon, reverse osmosis, and ceramics.

Both industrial and craft beer have been found to include microplastics, according to multiple studies.21 Other beverages including milk, iced tea, soft drinks, energy drinks, and wine have also been found to contain microplastics.22 

Microplastics in breast milk

The biggest risk of microplastics in breast milk comes from storing the milk in plastic bags, researchers have found.23 Baby bottles and accessories pose the risk of microplastics leaching into breast milk or other liquids. However, some limited research has found that might not be the only source: One 2022 study of 34 mothers in Italy spotted microplastics in 75% of their breast milk even though the milk was not collected or stored in plastic.24 This is concerning because infants would be exposed to potentially toxic effects of any chemicals associated with those microplastics, such as some plasticizers known as phthalates.

Microplastics in salt

Sea salt, rock salt, lake salt, and table salts have been found to include microplastics made up of a variety of plastic types. Research has found the highest concentrations of microplastics to occur in sea salt, likely due to higher levels of microplastic contamination in the seawater itself, especially if the salt came from Asian regions.25

Microplastics in honey

A review study found that both industrial and craft honey contain microplastics, mainly in the form of fibers. Particles of at least four different types of plastics were spotted in honey from industrial and craft samples, as well as in flowering plants and sugars from Germany, France, Italy, Spain, Mexico, Switzerland, and other countries. The authors noted that bees themselves can collect microplastics “from the air and their interaction with plants, soil, and water.”26

Microplastics in processed foods

To-go containers and disposable cups and vessels contain microplastics that could then transfer to the food they’re holding. Six studies published between 2014 and 2021 found nearly a dozen different kinds of microplastics in take-out containers of different shapes and sizes—along with cups, teabags, and baby bottles.27 

The way we handle these items ups the risk of creating microplastics. Microwaving plastic containers can contaminate food by releasing microplastic particles, and zapping may also release endocrine-disrupting chemicals such as phthalates that are used as plasticizers to make containers more flexible. In some cases, just opening plastic packaging, particularly bottle caps, can lead to microplastics plopping into your food or beverage.28

In some cases, just opening plastic packaging, particularly bottle caps, can lead to microplastics plopping into your food or beverage.

Packaged meats such as chicken breasts and turkey escalopes have been found to contain microplastics fragments.29 The microplastics contamination found in these meat samples likely came from the packaging in polystyrene trays.

Microplastics in eggs

A 2022 study found that chicken eggs purchased from local supermarkets in China (which produces more than 40% of the world’s eggs30) contained microplastic particles. Each egg averaged multiple microplastic particles, most of which were polyethylene, which is a type of resin used widely in everything from food wrap to fuel tanks. The study showed contamination to be higher in the yolk than the white, with no significant change after cooking.

Microplastics in plants

Apples and other fruits and vegetables such as pears, broccoli, lettuce, and carrots have been found to be contaminated by nanoplastics that have been absorbed by the plants themselves.31 Information on other produce, however, is limited. Researchers note that the nanomaterials accumulated in those plants “may be transferred to the consumer through diet,” but that more research on impacts is needed.

Common microplastics in food

Nearly all types, shapes, and sizes of microplastics can be found in food. A review of 136 studies related to microplastics in food and beverages found that polyethylene is the most common plastic type found in food.32 This kind of plastic is arguably the most commonly used in the world, and can be found in everything from packaging like plastic bags, containers, and films to insulation and cushioning. Aside from polyethylene, the most common plastic types found were polypropylene, another common resin found in packaging and plastic products including textiles, and polyethylene terephthalate, which is part of the polyester family. Those studies also found food, water. and beverages to be tainted by polyester, polyamide, rayon, cellophane, polystyrene, acrylic, polyvinyl chloride (PVC) and polyurethane.

Why are microplastics bad for humans?

While much research is still needed to fully understand the human health impacts of microplastics, there are concerns that certain plastics and additives, such as pigments and flame retardants, can be toxic. Plastics, even in their microplastic form, can also develop something known as the “plastisphere” that could also pose a risk to human health. The plastisphere is a biofilm made up of a diverse community of organisms like bacteria that can develop on the surface of any and all plastics. Researchers warn the plastisphere, which can also develop on microplastics, could be capable of carrying pathogens that can cause illness and disease. However, more research is needed to truly assess the risk to human health.

  1. Health toxicity effects of brominated flame retardants: From environmental to human exposure, Environmental Pollution, Sep. 2021 ↩︎
  2. Human consumption of microplastics, Environmental Science & Technology, Jun. 2019 ↩︎
  3. Microplastics and nanoplastics in food, water, and beverages; part I. occurrence, TrAC Trends in Analytical Chemistry, Feb. 2023 ↩︎
  4. Health effects of microplastic exposures: current issues and perspectives in South Korea, Yonsei Medical Journal, Sep. 2023 ↩︎
  5. Predicted growth in plastic waste exceeds efforts to mitigate plastic pollution, Science, Sep. 2020 ↩︎
  6. Microplastic in northern anchovies and common murres from the Monterey Bay, California USA, Environmental Pollution, Jan. 2023 ↩︎
  7. Uptake and effects of microplastics on cells and tissue of the blue mussel mytilus edulis L. after an experimental exposure, Environmental Science & Technology, Oct. 2012 ↩︎
  8. Agricultural application of microplastic-rich sewage sludge leads to further uncontrolled contamination, Science of the Total Environment, Feb. 2022 ↩︎
  9. Fate of microplastics in agricultural soils amended with sewage sludge: Is surface water runoff a relevant environmental pathway?, Environmental Pollution, Jan. 2022 ↩︎
  10. Soil microplastics pollution in agriculture, Science, Feb. 2023
    ↩︎
  11. Microplastics in food: A review on analytical methods and challenges, International Journal of Environmental Research and Public Health, Sep. 2020 ↩︎
  12. Microplastics and nanoplastics in food, water, and beverages; part I. occurrence, TrAC Trends in Analytical Chemistry, Feb. 2023 ↩︎
  13. Microplastics from consumer plastic food containers: Are we consuming it?, Chemosphere, Aug. 2020 ↩︎
  14. Plastic teabags release billions of microparticles and nanoparticles into tea, Environmental Science & Technology, Sep. 2019 ↩︎
  15. Microplastics generated when opening plastic packaging, Scientific Reports, Mar. 2020 ↩︎
  16. Assessing the telease of microplastics and nanoplastics from plastic containers and reusable food pouches: Implications for human health, Environmental Science & Technology, Jun. 2023 ↩︎
  17. Bioaccumulation and biomagnification of microplastics in marine organisms: A review and meta-analysis of current data, PLoS One, Oct. 2020 ↩︎
  18. Microplastics and nanoplastics in food, water, and beverages; part I. occurrence, TrAC Trends in Analytical Chemistry, Feb. 2023 ↩︎
  19. Microplastics in drinking water, World Health Organization, 2019 ↩︎
  20. Synthetic polymer contamination in bottled water, Frontiers in Chemistry, Sep. 2018 ↩︎
  21. Anthropogenic contamination of tap water, beer, and sea salt, PLoS One, Apr. 2018 ↩︎
  22. Multiple sources: Milk, Apr. 2020; Soft drinks, cold tea & energy drinks, Jul. 2020; White wine with plastic stopper, Nov. 2020 ↩︎
  23. Release of microplastics from breastmilk storage bags and assessment of intake by infants: A preliminary study; Environmental Pollution, Apr. 2023 ↩︎
  24. Raman microspectroscopy detection and characterisation of microplastics in human breastmilk, Polymers, Jul. 2020 ↩︎
  25. Global pattern of microplastics (MPs) in commercial food-grade salts: Sea salt as an indicator of seawater MP pollution, Environmental Science & Technology, Jul. 2018 ↩︎
  26. Microplastics and nanoplastics in food, water, and beverages; part I. occurrence, TrAC Trends in Analytical Chemistry, Feb. 2023 ↩︎
  27. Ibid. ↩︎
  28. Microplastics generated when opening plastic packaging, Scientific Reports, Mar. 2020 ↩︎
  29. Microplastics and nanoplastics in food, water, and beverages; part I. occurrence, TrAC Trends in Analytical Chemistry, Feb. 2023 ↩︎
  30. Research on Chinese consumers’ shell egg consumption preferences and the egg quality of functional eggs, Poultry Science, Oct. 23 ↩︎
  31. Micro- and nano-plastics in edible fruit and vegetables. The first diet risks assessment for the general population, Environmental Research, Aug. 2020 ↩︎
  32. Microplastics and nanoplastics in food, water, and beverages; part I. occurrence, TrAC Trends in Analytical Chemistry, Feb. 2023 ↩︎
Maddy Lauria
Maddy Lauria is a freelance environmental journalist who grew up in the Mid-Atlantic. She now lives in Delaware with her husband, young daughter, and far too many pets.