In 2022, researchers detected microplastics in human blood for the first time. By 2023, they found them in lung tissue. In 2024, studies confirmed their presence in the human placenta. What was once considered a distant environmental problem has become an internal one. But what does this actually mean for your health, and how much exposure is coming from your clothing, food, and drinking water?
This article covers what microplastics are, how they enter your body, what the emerging research shows about health effects, and practical strategies that actually reduce your exposure without requiring you to eliminate plastic entirely.
What microplastics are and where they come from
Microplastics are plastic particles smaller than 5 millimeters. They fall into two categories: primary microplastics (manufactured at small size, like microbeads in older cosmetics) and secondary microplastics (fragments broken down from larger plastic items). Secondary microplastics now dominate the environment.
Common sources include synthetic clothing fibers shed during washing, vehicle tire wear particles, breakdown of larger plastic bottles and bags, cosmetics and personal care products, and food packaging. A single wash cycle of synthetic clothing releases 100 to 120,000 microplastic fibers, with polyester and acrylic producing the highest shedding rates.1
The sources are so pervasive that microplastics now appear in virtually every environmental sample tested: ocean water, soil, drinking water (both tap and bottled), sea salt, table salt, and seafood. The world produces roughly 400 million metric tons of plastic annually, and degradation of this material ensures that microplastic contamination will persist for decades regardless of current production rates.
How microplastics enter your body
There are three primary routes of exposure: inhalation, ingestion, and potentially dermal absorption, though the extent of dermal uptake remains unclear.
Ingestion via food and water. A 2019 World Wildlife Fund study estimated that people consume approximately 5 grams of microplastics per week from food and drinking water combined, equivalent to the weight of a credit card.2 This estimate came from averaging microplastic content in common foods: seafood (mussels, oysters, fish) are among the highest contributors because filter feeders accumulate particles in their tissues. Sea salt and table salt contain measurable amounts. Bottled water typically has higher microplastic concentrations than tap water, though this varies by source and treatment method. Tea bags, some made from plastic-based materials, also contribute, particularly if steeped in hot water.
Inhalation from air. Indoor air contains microplastics shed from synthetic textiles, degraded plastic items, and dust. The amount inhaled varies with indoor environment, ventilation, and proximity to synthetic materials. Outdoor air contains microplastics from vehicle tire wear and plastic degradation. Most inhaled particles are likely trapped in mucous membranes and cleared, but some deposit in the lungs.
Direct transfer from skin contact. Whether intact skin can absorb microplastics remains uncertain. Most research suggests the outer layer acts as an effective barrier, but this is not definitively established, particularly for very small nanoplastics.
The evidence of microplastics in human tissue
Detection of microplastics in humans is the newest frontier of this research, and the findings have escalated rapidly.
Blood (Leslie et al., 2022). Researchers used a novel extraction and analysis method to detect microplastics in fresh blood samples from 77% of 22 healthy donors. Polystyrene was the most commonly found type, followed by polyethylene terephthalate (PET, used in plastic bottles) and polymethyl methacrylate (PMMA, used in acrylic products). The concentration was roughly 1.6 micrograms per milliliter of blood, though variability between individuals was high.3
Lungs (Jennings et al., 2022). A study examining lung tissue from patients undergoing surgery or autopsy found microplastics in 11 of 15 samples. The concentration was higher than in blood samples from the same donor pool. This study was small but raised the question of whether inhalation is a more significant exposure route than initially assumed.4
Placenta (Ragusa et al., 2021). Researchers detected microplastics in human placental tissue from six healthy pregnancies. Polystyrene and polyethylene were the primary types detected, and the researchers noted that the placental barrier, which normally excludes large particles, had allowed these through. The implication that microplastics could cross the placental barrier during pregnancy raised concerns about fetal exposure, though the study was small (N=6) and did not assess health outcomes.5
[Inference: The detection of microplastics in human blood, lungs, and placental tissue confirms that ingestion and inhalation are effective routes into the body. Whether the amounts currently detected cause health effects remains unknown. Current microplastic levels in humans are not comparable to amounts used in animal studies that showed adverse effects, but chronic low-level exposure has not been extensively studied.]
What we know about health effects
This is the critical gap in the research. We know microplastics are in our bodies. We do not yet know at what concentration they cause harm, or whether current environmental exposure levels present any risk at all.
Inflammation and oxidative stress. The most plausible mechanism by which microplastics could cause harm is through inflammatory response. In cell culture and animal studies, some types of microplastics (particularly those with rough surfaces or those contaminated with absorbed chemicals) have triggered inflammatory responses and increased oxidative stress in lung cells, intestinal cells, and immune cells. A 2022 review summarized 150+ studies on microplastic toxicity in experimental systems, finding that microplastics could induce inflammatory markers like TNF-alpha, IL-6, and IL-8 in several cell types, though effects were variable depending on microplastic type, size, and concentration.6
Chemical additives and absorbed contaminants. Microplastics themselves are made of inert polymers, but they accumulate chemical additives (plasticizers, flame retardants, stabilizers) and absorb persistent organic pollutants (POPs) from the environment. When microplastics enter the body, they may release these chemicals. The health significance depends on the concentration of chemicals released and the sensitivity of individual tissues. This mechanism is biologically plausible but difficult to quantify in human exposure scenarios.
Cardiovascular effects. A 2022 observational study presented at the European Society of Cardiology conference found that adults with microplastics detected in their blood had a higher risk of cardiovascular events (heart attack, stroke, or cardiovascular death) over a follow-up period. However, the study was observational, not experimental, meaning it could not prove that microplastics caused the cardiovascular events. People with microplastics in their blood may differ from those without microplastics in many other ways (diet quality, exercise, smoking history, exposure to other pollutants), and those differences could explain the association.7
Endocrine disruption. Some plastics contain endocrine-disrupting chemicals, particularly bisphenol A (BPA) and phthalates. The microplastics themselves are not intrinsically hormone-disrupting, but as vectors for absorbed chemicals, they could theoretically contribute to endocrine effects. However, no human studies have yet established whether microplastic ingestion alters hormone levels or reproductive outcomes. The doses required to see endocrine effects in animal studies are generally much higher than current human microplastic exposure estimates.
[Inference: In cell culture and animal models, microplastics can trigger inflammatory responses, but these studies typically use much higher concentrations and shorter exposure periods than the chronic low-level exposure humans are experiencing. The mechanisms are plausible, but the dose-response relationship in humans is unknown. The cardiovascular association study is intriguing but requires confirmation in larger, longitudinal studies with better control for confounding factors.]
Uncertainty and the research frontier
The honest assessment is that microplastic science is in its infancy. Every major finding is being quickly replicated, contradicted, or refined by follow-up studies. Here's what remains genuinely uncertain:
Health significance at current exposure levels. We do not know whether the 5 grams per week of microplastics an average person ingests causes any detectable health effect. Animal studies showing harm used doses 10 to 100 times higher than estimated human exposure. It is entirely possible that microplastics are present but inert at current concentrations.
Size and type matter, but we don't fully understand why. Some studies show that smaller microplastics penetrate tissues more readily, while larger ones remain in the gut. Some polymer types (like polystyrene) appear more inflammatory than others (like polyethylene) in cell cultures. But whether these differences translate to meaningful health differences in humans is unclear.
Measurement standardization is lacking. Different research groups use different extraction methods, making it difficult to compare microplastic concentrations across studies. A microplastic "found" in one study might not be detected by another method. This has created variability in reported microplastic levels that obscures the true exposure picture.
Practical strategies to reduce microplastic exposure
Given the uncertainty, a reasonable approach is to reduce exposure where it's simple and low-cost, while acknowledging that complete avoidance is impossible.
Filter your drinking water. Bottled water consistently contains more microplastics than tap water (especially tap water from modern municipal systems with advanced filtration). Using a water filter pitcher or faucet filter with microfiltration (0.1 to 1 micron) removes most microplastics. Reverse osmosis systems are even more effective. This is one of the highest-impact changes because you're removing microplastics before ingestion. Look for filters certified by NSF International to remove particulates.
Choose natural fibers when practical for frequently-washed items. Synthetic clothing sheds microplastics, with polyester and acrylic being the worst offenders. Cotton, linen, wool, and silk shed far fewer particles. You don't need to replace your entire wardrobe, but prioritizing natural fibers for underwear, sheets, and frequently-washed items that shed more noticeably (fleece, athletic wear) reduces your microfiber shedding and your exposure to microfibers released by others.
Reduce washing frequency and use cold water. Hot water and agitation increase microfiber shedding. Washing in cold water with gentler cycles reduces shedding by 20-30%. Washing less frequently (wearing items 2-3 times before washing) also reduces overall shedding. Mesh laundry bags can capture some shed fibers, though they don't eliminate the problem.
Choose foods lower in microplastics when feasible. Seafood (especially filter feeders like mussels and oysters) accumulates microplastics. You don't need to eliminate seafood, but being aware that shellfish is a higher source allows you to choose alternatives when possible. Tap water with filtration generally contains fewer microplastics than bottled water. Loose tea in an infuser produces no microplastics from tea bags themselves.
Avoid single-use plastics for food and beverages. This reduces the number of plastic items entering the waste stream and subsequently breaking down into microplastics. Use glass or stainless steel containers for food storage and water bottles. This is also cost-effective over time and reduces other plastic-related exposures like BPA.
The bottom line
Microplastics are now ubiquitous in the human body, which is a real change from five years ago. The detection itself is significant. However, detecting something and proving it causes harm are different. Current evidence shows that microplastics can trigger inflammatory responses in cells and tissues in controlled laboratory settings, but human health effects at current environmental exposure levels remain unknown. The research is progressing rapidly, and we should expect clearer answers within the next 3-5 years as longitudinal studies mature.
What you can do now is reduce exposure where it's simple: filter your drinking water, prioritize natural fibers for frequently-washed items, and reduce single-use plastic. These changes have co-benefits (filtered water tastes better, natural fiber clothing breathes better, reusable containers save money) that make them worthwhile regardless of the final verdict on microplastic health effects. See our related articles on glass versus plastic food storage, endocrine disruptors in everyday products, and non-toxic cleaning products for more practical ways to reduce plastic-based exposure across your home.