The Average American Has Already Ingested 11 kg Worth of Microplastics, New Study Finds

WellnessPulse researchers analyzed most of the available, peer-reviewed scientific studies on microplastics and found that we ingest around 2.87 kg (6.3 lbs) of microplastics each decade.

The median age of a U.S. citizen is around 39 years, and by that time, they have already ingested around 11 kg of microplastics, according to the findings of the latest WellnessPulse study.

Luckily, most ingested microplastics don't stay in the body. Still, when they do, their highest concentrations are found in the blood and the brain, raising questions about microplastics' potential impact on health.

Due to plastic’s durability and widespread use, microplastics are now detected virtually everywhere — from the atmosphere and oceans to the food chain.

The WellnessPulse research team calculated how much plastic we ingest overall and the amount our bodies retain at different ages. They also looked into which body parts contain the most microplastics.

Data suggests that at least 17 organs and tissues contain microplastics: the blood, brain, breast milk, cardiovascular system, uterus, eye, heart, kidney, large intestine, liver, lungs, placenta, semen, small intestine, spleen, testicle, and tonsil.

The brain was found to have some of the highest microplastic concentrations, about 13 times higher than the kidney, which sits at the bottom of the top 10 list of organs and tissues containing the most MPs.

According to the WellnessPulse analysis, the average 10-year-old has already ingested 2.87 kg (6.3 lbs) of microplastic. The amount grows to nearly 23 kg (around 50 lbs) by 80.

It’s noteworthy that not all microplastics stay in the body. The average 10-year-old may retain 0.11 g of MPs. By the age of 80, the body has accumulated around 0.92 g of microplastics.

The WellnessPulse research team analyzed 20 studies evaluating the presence of microplastics in specific human organs and tissues. They extracted data on microplastic particle number, organ mass, or microplastic particle concentration measures manually and using AI tools.

Then, they aggregated data by averaging all the available data points to produce a single value, such as the concentration of microplastics in a specific organ.

Read the full methodology here.

How much microplastic do we ingest?

We may ingest and inhale large amounts of microplastics throughout our lives, but most don't stay in the body. The WellnessPulse research team calculated how much microplastic the average American is exposed to and accumulates in their bodies throughout their lifetime.

An average 10-year-old has already ingested 2.87 kg (6.3 lbs) of microplastics, which is as much plastic as a lawn chair. However, the amount of MPs retained in the body at this age is only 0.11 g.

From the very early days, children are exposed to microplastics through milk and infant formulas, as well as plastic toys and foods that come in plastic packages.

Studies examining MPs' effects on children are particularly limited, partly due to ethical considerations such as the ability to give informed consent. However, some preliminary evidence links exposure to microplastics during the first weeks of life to the development of reproductive and neurological diseases in adulthood.

As we age, the exposure to microplastics and the amount of them accumulating in our bodies is only increasing.

By the age of 40, an average American has ingested a staggering 11.48 kg (25.3 lbs) of microplastics, which would equate to a recycling bin on wheels. However, only 0.46 g of MPs stay in the body.

Some evidence from laboratory models suggests that microplastics accumulating in the adipose tissue may accelerate aging. However, aging is a complex process determined by multiple factors, including our genes and their regulation, and rigorous human studies are needed to understand the relationship between MPs and the pace of aging.

The average American lives nearly 80 years in the U.S. By this age, they have ingested 22.97 kg (50.6 lbs) of microplastics, equal to a medium-sized plastic canoe. The number of MPs retained in the 80-year-old body is much lower, 0.92g.

This means that by the end of their lives, Americans may accumulate the amount of microplastics worth around two plastic straws.

Most microplastics are found in the blood

Studies identified 17 human organs and tissues that contain microplastics, ranging from the vital organs like the brain and the heart to reproductive organs like the placenta and testicle.

Below, you can find the amount of microplastics found in 10 organs and tissues with the highest concentrations in an average person living in the U.S.

The concentration is calculated as the ratio of microplastic mass in milligrams per gram of organ or tissue.

Blood, a tissue that transports oxygen, nutrients, and hormones, has the highest concentration of microplastics, 1.6 mg per gram of tissue, according to the WellnessPulse analysis. This amount is nearly 43 times higher than in the brain, the organ with the second-highest concentration of microplastics. A study from 2024 suggests that people who had microplastics in the plaques in their blood vessels were 4.5 times more likely to have a heart attack, stroke, or die. While the study didn’t prove microplastics caused these conditions, it raised the possibility that MPs may be a previously unknown risk factor.

The brain, the complex organ that regulates everything we do, contains 0.0374 mg of microplastic per gram of organ. A recent study indicates that people diagnosed with dementia may have up to 10 times higher microplastic concentrations in the brain than those without the condition, raising questions about the potential microplastics’ role in disease development.

With 0.0325 mg of microplastics per gram of organ, the testicle, an organ responsible for making sperm and male sex hormones, has the third-highest concentration of microplastics among the organs and tissues included in the analysis. Research in dogs associated higher amounts of certain microplastics with reduced sperm counts, highlighting the potential consequences on human male fertility. However, the findings in animal models can not necessarily be applied to humans.

Despite being the only temporary organ in the human body that forms during pregnancy, the placenta still contains microplastics, 0.0195 mg per g of organ. As it provides oxygen and nutrients to a fetus, the presence of microplastics raises concerns over their potential harm to a developing baby. Scientists warn that because MPs contain substances that act as endocrine disruptors, they could cause long-term effects on human health.

The tonsil is among the five organs and tissues with the highest MP concentrations, containing 0.0169 mg of microplastic per gram of organ. Located at the back of the throat, this tiny organ stops germs from entering the body through the mouth or the nose. However, some evidence indicates that tonsils are a potential entry point for nanoplastics — extremely small microplastics — into the human body.

The lungs, organs that make oxygen available to our body, contain 0.0148 mg of microplastics per gram of organ, according to the WellnessPulse analysis. This suggests microplastics can infiltrate our bodies when we inhale. Scientists believe that once in the circulatory system, microplastics may cause conditions like asthma, pneumonia, and allergic reactions.

As a vital organ, the liver performs hundreds of functions necessary to sustain life, including removing various substances from the blood. Despite its ‘detoxing’ function, the liver has 0.0130 mg of microplastics per gram of organ. Microplastics are thought to damage the liver, as chronic exposure may raise the risk of nonalcoholic fatty liver disease.

Microplastics can enter different organs, and the eyes are no exception, as they contain 0.0118 mg of microplastics per gram of organ. One unexpected source of microplastics in the eyes could be contact lenses. According to a 2023 study, reusable lenses exposed to sunlight over a prolonged period can shed microplastics, although the health impact remains unclear. Moreover, the authors of a pre-print from 2024 discovered microplastics in over-the-counter lubricant eyedrops.

The spleen is a small organ inside the left rib cage responsible for filtering blood and removing old red blood cells, as well as hosting some immune system cells. The WellnessPulse analysis found that it contains 0.0034 mg of microplastics per gram of organ. In bird models, exposure to microplastics induced spleen inflammation. However, as the findings in animals may not necessarily be transferred to humans, more studies are needed on MPs’ effects on the spleen.

The kidney is another vital organ that made it to the list of organs and tissues with the highest MP concentration, containing 0.0028 mg of microplastics per gram. Evidence in mice suggests that microplastics may cause kidney damage, especially when combined with the environmental contaminant benzo(a)pyrene.

It’s noteworthy that existing evidence doesn’t prove that microplastics accumulating in the body can cause the conditions mentioned above. Studies in humans remain limited, while many studies in animal models show mere associations rather than causal relationships.

The takeaway

The analysis by the WellnessPulse research team reveals that 17 organs and tissues accumulate microplastics, with the highest concentrations found in the blood, brain, and testicle.

We ingest about 2.87 kg of microplastics each decade.

Because microplastics were discovered two decades ago, a lot is yet to be understood about their impact on human health. However, increasing evidence highlights the potential role of MPs in the development of a wide range of conditions, such as dementia, asthma, and nonalcoholic fatty liver disease.

Methodology

To calculate the amount of microplastics in each organ and tissue, the WellnessPulse research team first reviewed scientific literature found on PubMed, Web of Science, and Google Scholar.

They selected studies evaluating the presence of microplastics in specific human organs and tissues and providing information on microplastic particle count per organ sample, organ sample mass, or concentration of microplastic particles in the organ or tissue.

Studies analyzed included information on adult individuals of one or both sexes of all health statuses.

One researcher extracted data on microplastic particle number, organ mass, or microplastic particle concentration measures manually and using AI tools from the original publication text or supplementary material.

After the data extraction, one researcher cross-checked and validated the data's accuracy.

The collected raw data was checked manually for input errors, and the data on microplastic particle numbers from different publications were aggregated by averaging all the available data points to produce a single value and avoid data duplication.

The relevant data was calculated as follows:

Then, relevant data was visualized for clarity and readability purposes.

Limitations of the study

The study is subject to multiple limitations that may affect the accuracy of findings. They are the following:

• There were differences in study sample sizes, biological sex distributions, health statuses, and participants' exposure to plastics.
• Differences in study designs and microplastic extraction and analysis methods.
• Estimates were calculated using currently very limited data, especially on average microplastic particle mass, human exposure to microplastics, and the accumulation of microplastics in the body.