21 Microplastics in Our Food and How They Got There

Introduction

(Green America)

As mentioned before, microplastics are defined as plastic particles that are smaller than 5 mm each. Microplastics come from many things like single waste plastic as well plastic dumping from large corporations. In this day and age, microplastics are everywhere from the land, oceans, lakes, and in our food. (CJ)

Due to microplastic being almost everywhere and the planet and continuing to grow, they have become a large concern for countries across the world. In January 2025, 25 countries united to combat plastic pollution through the Global Plastics Action Partnership. This program focuses on promoting recycling plastics and reducing emissions from the plastics sector while also growing the job force with environmentally friendly jobs (World Economic Forum). (CJ)

We also see large evidence of microplastics being in our food. Many studies have been done on food products like seafood, salt and sugar, drinking water, as well as many other food items. Within these studies, almost all food groups showed significant evidence that microplastics are within our foods. These plastics can come from production, storage, and packaging. In the case of seafood, most of the microplastics come from the fish consuming the microplastics from their food. Like mentioned in the previous chapter, phytoplankton consume small foods and many times, they think the microplastics are food. These plastics move up through the food chain and into the food that we consume as humans. Microplastics are becoming more and more prevalent and are working their way up through the production and food chains. This presents a whole host of issues that we need to solve before they become detrimental to the planet and human health. (CJ)

In this chapter, we will go in depth into how microplastics get into our soil and food and how that affects human and environmental health. We will also explore how we can mitigate this issue and what solutions are available to us. Also, we will review what initiative has already been taken against the microplastic issue and how effective they are or could be in a larger population. (CJ)

Section 1: How Microplastics Enter Soil

(Wiley)

There are many sources of microplastics in our environment that come from agriculture, urban planning, and many others. Everything we do as a country and as a world population increases the amount of microplastics. (CJ)

Agricultural activities are one of the main ways that microplastics end up in our soil and food. One of the main ways this happens is through plastic mulching. This is something that is done in large farms as well as home gardens. Plastic mulching is when a small plastic film is placed over the soil to conserve moisture and suppress weed growth. While this technique works well, it starts to break down and releases small particles of plastic into the soil. There are also slow-release fertilizers and pesticides that release plastic into the environment. The chemicals are in a plastic coating to control the release of the nutrients but when they break down, they are a persistent soil pollutant. (CJ)

Another major contributor to plastic pollution by agricultural practices is the irrigation systems and the use of greenhouses. Plastic and cheap and easy to use as drainpipes when creating an irrigation system for a farm or garden but with persistent sun exposure and mechanical stress, they start to break down and release plastic particles. This is the same for greenhouses. While they are used to prolong the growing period of plants, they can break down and add more plastic into the environment. (CJ)

The increase in plastic pollution can also be caused by urban planning. One of the main ways is through poor waste management. If a community has inefficient waste collection, a lack of recycling facilities, and improper disposal techniques, it can lead to a large buildup of plastic litter that can seep into our lands. This also leads to how the stormwater and drainage systems work within a city. Most cities’ drainage systems fail to filter out the plastic particles leading to them flowing out into the rivers and oceans. (CJ)

Another form of plastic pollution from urban planning is the construction materials. Most of the construction materials that are used to build new cities and neighborhoods are made or packaged in plastic. During the construction phase, many of these are not properly disposed of. Either they get blown around due to weather changes during the construction period or they can be buried by the different construction practices. Overall, a very small percentage of the waste created during a project is properly disposed of. (CJ)

Lastly, the plastic pollution can come from the people living in these urban areas. In the time of fast fashion, many of our clothes are made of synthetic or plastic materials. When these are washed in conventional washing machines, the particles are released into the water and are run through the drainage system. Based on current estimates, more than 35% of the microplastic currently floating in the ocean comes from laundry, which would make this the largest single source of plastic in the ocean. (Everyday Recycler) Microplastics can also come from parks within these communities. Many parks use plastic or rubber mulch to protect falling children. These break down and get released into the soil or get caught in stormwater runoff. (CJ)

There are many ways that microplastics spread throughout our environment once they enter through agriculture, urban planning, or the many other ways. Once they enter the soil, these tiny plastic particles are transported and dispersed through various natural and human-driven processes. Their movement affects soil health, water quality, and even plant life, making it crucial to understand how they spread. (CJ)

One of the major ways microplastics move through soil is by water infiltration and runoff. During rainfall or the irrigation of land, water carries microplastics across the surface or pushes them deeper into the soil layers. The surface runoff can transport microplastics into nearby water bodies like lakes, rivers, and oceans. Additionally, animals that live in the soil, such as earthworms and insects, play a role in microplastic movement. As these organisms burrow and digest soil, they redistribute microplastics within different layers, potentially increasing their spread. (CJ)

Microplastics also interact with soil particles through adsorption, where they bind to organic matter and minerals. Depending on their composition, some remain near the surface, while others become embedded deeper into the soil. Over time, leaching can occur, allowing microplastics to move downward into groundwater systems, raising concerns about potential contamination of drinking water sources. (CJ)

Once microplastics are introduced into soil ecosystems, they interact with soil particles, resist degradation, and influence physical and chemical properties, ultimately impacting soil fertility and productivity. Understanding their fate in soil is crucial for assessing environmental risks and developing mitigation strategies. (CJ)

Microplastics interact with soil particles through physical and chemical processes. Their size, shape, and chemical composition determine how they bind to organic matter and minerals. Smaller microplastics, such as microfibers and microbeads, can become embedded within soil pores, while larger pieces may gather on the surface. Hydrophobic plastics (plastics that do not interact with water) tend to attach to organic matter, while hydrophilic microplastics may interact with minerals through electrostatic bonds. These interactions influence how microplastics move through the soil and their potential for leaching into groundwater. (CJ)

Degradation of plastics rely on many different environmental factors. Temperature, moisture levels, microbial activity, and exposure to UV radiation all influence how quickly plastics break down. However, soil environments typically have a lower UV exposure than aquatic ecosystems, slowing the degradation process. Additionally, some plastics are more resistant to microbial degradation, meaning they can remain in the soil for decades. (CJ)

The presence of microplastics also alters soil structure, texture, and fertility. Their accumulation can disrupt soil clumping, porosity, water retention, and drainage. While some microplastics may improve aeration, excessive amounts can lead to soil compaction, limiting root growth and water infiltration. Additionally, microplastics can absorb harmful substances like heavy metals and pesticides. This action can disrupt the chemical makeup of the soil which can continually harm plant growth throughout multiple growing seasons. (CJ)

Section 2: Transfer of Microplastics from Soil into Food

(MDPI)

Once the microplastic enters the soil, they can then enter our plants, leading to them entering our food. These tiny plastic particles can be absorbed by plant roots, affect growth and development, and even accumulate in edible parts of crops. (CJ)

One of the primary ways microplastics enter plant systems is through root uptake. When plastic particles are small enough—usually in the nanometer to micrometer range—they can pass through tiny openings in root cells, either with water and nutrients or through active cellular processes. Once inside the root system, these particles can travel through the plant’s vascular tissues, distributing them to other parts of the plant. (CJ)

A major concern is the accumulation of microplastics in edible plant parts, such as fruits, vegetables, and grains. Once microplastics enter a plant’s vascular system, they can be transported to leaves, stems, and reproductive structures. Research has shown that crops like lettuce, wheat, and carrots can accumulate microplastics, raising concerns about human exposure through food consumption. Although the long-term health effects of ingesting microplastic-contaminated crops remain under study, their presence in the food chain highlights significant risks. Zhang, S., Wang, J., Gao, Y., et al. (2020) Detecting and quantifying microplastics in food products remains a significant challenge due to their small size, complex composition, and the limitations of current analytical techniques. (CJ)

One of the major challenges in detecting microplastics in food is the diverse size, shape, and chemical composition of all the different types of plastic. Microplastics range from large visible fragments to microscopic particles that are difficult to analyze. Additionally, their composition varies widely, each requiring different identification techniques (Smith et al., 2018). The potential contamination from laboratory equipment, packaging, and environmental exposure further complicates accurate quantification, leading to concerns about cross-contamination during analysis (Karbalaei et al., 2019). (CJ)

Another issue is the lack of standardized methods for detecting microplastics in food. Most analyzation practices have a very strict set of rules and procedures to follow when it comes to analyzing its composition. For example, our water testing and filtration system is standardized throughout the state and the country, but it is not the same with food. Because of the complex makeups of the many different foods that are affected by microplastics, it is increasingly difficult to set the testing standards. (CJ)

There are many early case studies when it comes to studying microplastics in our food. The largest number of plastics have been found in our seafood and food that has gone through a large amount of processing. A study analyzing oysters and mussels from Chichester Harbour, England, found up to 11,220 fibers per kilogram in oysters. The high levels of microplastics were attributed to fiberglass particles from boat maintenance activities, illustrating how localized environmental factors can influence contamination levels. (Food and Wine) When our food is consuming plastic as their food, it all gets passed up through the food chain. (CJ)

Highly processed foods, such as plant-based nuggets and breaded shrimp, have been found to contain higher levels of microplastics. The processing methods and packaging materials contribute to this contamination, emphasizing the challenges in assessing microplastic levels in complex food products. (EatingWell) While the largest amount of plastic in our bodies that comes from food does not come from our produce, it is important to have the knowledge that microplastics are found everywhere and we need to stay vigilant when it comes to watching what we eat. (CJ)

Section 3: Effects of Microplastics in Food on Human Health

(TonToTon)

There are many potential health effects of consuming microplastics from our food. Like mentioned before, many plastics can be consumed through plastic within our soil and food, but it can also be leached into our food and water through plastic containers. Heating food in plastic and drinking out of plastic water bottles are all ways we consume microplastics. Consuming this many plastics in our everyday lives can have detrimental effects on our health. (CJ)

Consumption of microplastics has shown to have a large effect on our heart health. A 2024 study found that individuals with heart disease who had microplastics in their arterial plaque faced double the risk of heart attacks or strokes compared to those without such exposure. (Environmental Working Group) This combined with the existing heart health problem happening within the US due to poor diet, poor exercise habits, and many other factors, can prove to be a large problem for the US population. (CJ)

The consumption of microplastics has also been linked to many forms of cancer, specifically lung cancer. When microplastic are small enough, they can be distributed through the air and breathed in. When inhaled, they can increase lung inflammation and can cause the cells to be disrupted, which causes cancer. This is similar to how it causes cancer within the rest of the body. The microplastics, when in the body, disrupts the way the cells mature and divide. This can cause the growth of tumors in the body, benign or malignant. (CJ)

They are also linked to many different neurological effects. Microplastics have been found in human brain tissue, particularly in the prefrontal cortex, which is associated with decision-making and behavior. While a direct causal link to neurological diseases like dementia hasn’t been established, the presence of these particles in brain tissue is concerning. (Insider) When consumed, the plastics can move through the bloodstream into the brain and accumulate. This build up can cause many problems like memory loss, and trouble making decisions. (CJ)

While all of these findings are very concerning, there is still a large gap in the research when it comes to how microplastics are affecting our bodies and health. Many of the studies that have been conducted are done on animals. While animal studies can show good correlation with human health, it is not an exact science. But, with more microplastics being consumed by humans every day, we are going to be able to start seeing more and more health problems that could be linked to the ingestion of microplastics. (CJ)

There are many risks when it comes to the overconsumption of microplastics in our food. Microplastics can be a large endocrine disrupter which affects all of the glands in the human body as well as the reproductive systems in both males and females. A study conducted in Italy found microplastics in the ovarian follicular fluid of 14 out of 18 women. This fluid is crucial for the proper development of eggs and this contamination can be very worrying (The Guardian). There was also recent research published within Toxicological Sciences that tested both human and canine testicular samples. In the study, they found that humans had a much higher amount of plastic in the samples compared to the canine samples. This is concerning because the plastic can interfere with spermatogenesis and can affect fertility (People). (CJ)

There is also a large risk about how the microplastics accumulate within the organs of the human body. The biggest worry that we have is the accumulation of plastic within the brain. A study published in Nature Medicine shows the microplastics can accumulate in brain tissue with concentrations up to 30 times higher than what is found in the liver and kidneys. It also showed a correlation between dementia and microplastic accumulation showing that people with dementia had up to 10 times the amount of plastic in the brain compared to those without dementia. More research needs to be done to fully understand the effects of microplastics in the brain, but the preliminary findings are very concerning (Reuters). (CJ)

There is also a possible link to the accumulation of microplastics in arteries and the chance of adverse heart conditions. A study led by Dr. Ross Clark from the University of New Mexico discovered significant amounts of microplastics in the arteries of stroke victims—51 times more than in individuals with healthy arteries. These particles were found within arterial plaque, suggesting a potential role in cardiovascular diseases (NYPost). (CJ)

While microplastics can cause harm in all systems of the body, the last system that is the most concerning is the effects of microplastics on the respiratory system. Using laser direct infrared spectroscopy, researchers identified microplastics ranging from 20–100 μm in various human tissues. The highest concentration was in lung tissue, averaging about 14 particles per gram. Polyvinyl chloride (PVC) was the dominant polymer found. These plastics embedded within the lung tissue can affect how the lungs absorb oxygen, get rid of CO2 waste, and how they fight off respiratory infections (PubMed). (CJ)

The presence of microplastics in various human organs including the brain, cardiovascular system, lungs, and many other systems highlight the widespread nature of exposure. While the full health implications are still being studied, the accumulation of these particles raises significant concerns about potential impacts on human health. (CJ)

Despite the large amount of information that we have on microplastics in our food, and they are affecting the human body, there are still large gaps within the research. One of the largest gaps in the research lies in what or who we are doing research on. Most of the research being done currently is being done on animals and in vitro studies. More human based research needs to be done to help fill this gap but that comes with some ethical complications. Without giving humans more plastic to ingest to see how it affects them, we have to find willing participants who have already consumed large amounts of microplastics. It is also difficult because the best research on how microplastics affect the body are done postmortem and finding research participants for that can be difficult. (CJ)

Another gap is in how the research is conducted. There is no standardized method in conducting research on microplastics unlike most other types of research. By creating a standardized method in detecting and quantifying the presence of microplastics within food and the human body, we will be able to better compare the studies to each other for the most accurate information. (CJ)

Section 4: Environmental Impact of Microplastics

(ReworldWaste)

Microplastics can alter the composition and function of the microbes in the soil. Certain bacteria thrive on the plastics and when these get into the soil, they create what is called a plastisphere. This is a biofilm that forms in the soil that can harbor other bacteria and pathogens that can disrupt the good bacteria within the soil. This increases the potential for diseases and pollution to spread throughout the soil and into plants. Another essential part of soil health are Earthworms, and they are affected by this as well. Exposure to microplastics has been shown to decrease their body weight and inhibits their ability to properly burrow into the soil. This leads to decreased soil aeration and fertility. All of these factors that microplastics change within the soil can also lead to poor nutrient cycling and water retention (Wikipedia). (CJ)

Not only can microplastic accumulate in humans but can also accumulate in wildlife. Recent studies have shown that microplastics can accumulate in pollinators like honeybees. This accumulation can impair the bee’s memory, reduce their ability to associate floral scents with nectar, and increase mortality rates. The particles can get into the bee’s brains and alter gene expression related to immunity, potentially contributing to colony collapse (The Washington Post). (CJ)

Plastic particles have also been found inside birds and other mammals. Microplastics have been found inside the lungs and digestive tracts of various bird species. A study analyzing 51 bird species found microplastics in all specimens’ lungs, with terrestrial birds showing a higher burden than aquatic ones. The particles included polyethylene, polyurethane, and PVC, indicating widespread airborne plastic pollution (The Guardian).  In mammals, microplastics have been found in species ranging in size from small rodents to rhinos. This indicates a large spread of microplastics across the land environment (Mongbay). (CJ)

Section 5: Proposed Solutions to the Microplastic Problem

While the microplastic issue seems like it is never ending, there are some solutions that we can take to ensure that the problem does not continue to worsen, and maybe even get better. We need a global initiative towards solving the microplastic crisis because this is a global issue. With better policy, more scientific advancements, better agricultural practices, and public awareness, we can lessen the effects of microplastics in our environment. (CJ)

We need to implement and enforce better policy at all levels including global, national, state, and local. There are a few international efforts that are happening right now to reduce the amount and the effects of microplastics. One of them is the Global Plastics Treaty. The United Nations is negotiating a legally binding treaty to end plastic pollution, emphasizing the reduction of plastic production and the elimination of single-use plastics (World Wildlife). There is also the Basel Convention. As of 2019, 187 countries have agreed to control the transboundary movements of plastic waste, aiming to minimize its impact on the environment. The Basel Convention includes almost all countries in the treaty except for the United States (CIEL). (CJ)

There are also some national and local policies that are already in place that we have the opportunity to expand on. One of them is single use plastic bans in certain cities, states, and countries. Numerous countries have implemented bans on single-use plastics, such as checkout bags and disposable tableware, to curb plastic waste (PMC).  Another regulation that some forms of government are exploring are stricter microplastic regulations. Governments are exploring policies requiring microfiber filters in washing machines and promoting consumer-awareness initiatives to reduce microplastic pollution from textiles and tires (OECD). (CJ)

To help solve the microplastic problem, we need to innovate solutions that could replace single use plastic in our day to day lives. Many universities are currently doing research into biodegradable plastics and plant-based plastics. Plant based plastics are made out of plant polymers that mimic the plastic we usually use. This way, if they are not properly disposed of, they will not release plastics into the environment when they degrade (University of Portsmouth). This is very similar to biodegradable plastics. UC San Diego is doing research on another type of plant polymer-based plastic that completely biodegrades in 7 months. These options offer promising alternatives to single use plastics (UCSD). (CJ)

We also need to innovate our waste management system to filter out the plastics, so they do not get into our water sources and continue to spread. The largest innovation for this is microplastic filters. Advances in wastewater treatment technologies, including physical, chemical, and biological processes, are enhancing the removal of microplastics from aquatic systems (ScienceDirect). (CJ)

In agriculture, reducing plastic use is important to preventing soil contamination. The adoption of biodegradable mulch films is one strategy, although there are challenges such as cost and durability (ScienceDirect). Researchers are also advocating for more sustainable use, collection, and recycling of agricultural plastics to limit pollution (Nature Communications). Practices like organic farming and permaculture are emphasized as ways to minimize synthetic material use and reduce the introduction of microplastics into the soil, although even organic systems must monitor contamination risks from fertilizers and compost (ScienceDirect). (CJ)

Public awareness and behavior change are also critical. Campaigns like the UN Clean Seas Campaign aim to increase global awareness about microplastic pollution and encourage behavioral changes to reduce plastic consumption (UNEP). Organizations like the Plastic Pollution Coalition provide educational resources and toolkits to help individuals and institutions reduce plastic use and advocate for systemic solutions (Polynext Conference). Consumer-facing efforts, such as the promotion of zero-waste stores and sustainable packaging, are enabling more people to reduce single-use plastic consumption by choosing refillable or environmentally friendly packaging options (SFGate; Bristlo). (CJ)

Conclusion

Microplastics have emerged as a dangerous environmental contaminant, infiltrating soil, food systems, and ecosystems worldwide. These tiny plastic particles enter the soil through pathways such as the degradation of plastic mulches, the application of sewage sludge and compost, and atmospheric deposition. Once in the soil, microplastics can affect soil structure, reduce fertility, and disrupt the biodiversity of microorganisms, earthworms, and other vital parts of the environment. Their accumulation in crops and livestock also facilitates their entry into the human food chain, raising concerns about potential health risks including inflammation, endocrine disruption, and bioaccumulation of harmful chemicals. Furthermore, microplastics negatively impact ecosystems by interfering with nutrient cycling, water retention, and food webs, while contributing to long-term habitat degradation and biodiversity loss. (CJ)

To address this growing challenge, a range of solutions has been proposed and implemented. Policy measures—including international treaties, national bans on single-use plastics, and regulations to reduce microplastic emissions—are paving the way for systemic change. Technological innovations such as biodegradable plastics, improved waste management systems, and microplastic filtration technologies offer promising tools to limit pollution. In agriculture, the adoption of biodegradable alternatives to plastic mulch and improvements in soil management can help reduce microplastic accumulation. Public awareness campaigns and shifts toward sustainable consumer behaviors further strengthen these efforts, highlighting the collective role of individuals, industries, and governments in reducing plastic waste. (CJ)

Looking ahead, it is clear that further research is urgently needed to better understand the degradation, fate, and removal of microplastics in various environments. There is a critical need for the development of scalable technologies that can effectively capture or degrade microplastics without causing secondary pollution. Equally important is fostering global collaboration across scientific, policy, and industrial sectors to develop unified strategies to mitigate microplastic contamination. Ultimately, integrating sustainability principles into agricultural practices, industrial production, and waste management will be key to preventing future plastic pollution and protecting both human and ecological health. (CJ)