Microplastics
Plastic particles are now in human blood, breast milk, placentas, and Arctic ice — and we don't yet know what that means for health.
The short version
- Microplastics — particles smaller than 5mm — have been found in virtually every environment on Earth: ocean trenches, mountain air, Arctic ice, and the human body, including blood, lungs, placentas, and breast milk.
- The average person is estimated to ingest roughly 5 grams of plastic per week — the equivalent of a credit card — through food, water, and air.
- The health effects of microplastic and nanoplastic exposure are actively being studied; early research has linked microplastics in cardiovascular tissue to significantly elevated risk of heart attack and stroke.
- Plastic production has grown so large — 400 million metric tons per year, doubling roughly every 15 years — that the pollution trajectory cannot be meaningfully addressed without reducing production itself, not just managing waste.
What it is
Microplastics are plastic fragments smaller than 5 millimeters in diameter — a classification that ranges from small pellets visible to the naked eye down to nanoplastics smaller than 1 micrometer, invisible without specialized equipment. They originate through two pathways. Primary microplastics are intentionally manufactured at small sizes: plastic pellets (nurdles) used as industrial feedstock, microbeads in personal care products (now banned in several countries), and fibers shed from synthetic textiles during washing. Secondary microplastics form when larger plastic items — bottles, bags, packaging, fishing gear, vehicle tires — break down through UV radiation, mechanical abrasion, and weathering into progressively smaller fragments. The breakdown process is physical rather than chemical: the polymer chains do not dissolve or biodegrade on any human-relevant timescale; they simply fragment into smaller and smaller pieces.
The global distribution of microplastics is now essentially total. They have been found at the bottom of the Mariana Trench (nearly 11 kilometers below the ocean surface), in the air above the Pyrenees at remote mountain stations far from industrial activity, in Arctic and Antarctic ice cores, in the soil of every agricultural region tested, and in drinking water from virtually every source, including municipal tap water and commercially bottled water. The ubiquity reflects the volume of plastic produced: since the 1950s, humanity has produced approximately 9 billion metric tons of plastic, of which roughly 9% has been recycled, 12% incinerated, and 79% accumulated in landfills or the environment. Annual production now exceeds 400 million metric tons and continues to grow. Much of what enters the environment never leaves.
Microplastics in the human body were long assumed to be limited to the digestive tract — ingested particles that passed through without significant absorption. That assumption was overturned by a series of studies beginning in 2020. Microplastics have now been detected in human blood (a 2022 study in Environment International found plastics in 77% of donors tested), in the placenta of newborns (a 2020 Italian study), in human lung tissue from surgical specimens, in breast milk, and in arterial plaque. The presence of plastics in arterial tissue was the subject of a landmark 2024 study in the New England Journal of Medicine: patients who had microplastics or nanoplastics in their carotid artery plaque were approximately 4.5 times more likely to experience a heart attack, stroke, or death over a 34-month follow-up period than patients whose plaque contained no detectable plastics. The study established association, not causality — but the magnitude was large enough to be clinically significant.
The health effects of microplastic exposure are an active and rapidly evolving field. Plastics are not inert: plastic polymers contain and release hundreds of chemical additives including plasticizers (phthalates, bisphenols), flame retardants, colorants, and stabilizers, many of which are endocrine disruptors with documented effects on hormone function, reproductive health, and development. Plastics also adsorb persistent organic pollutants — PCBs, pesticides, industrial chemicals — from the surrounding environment and can concentrate these compounds relative to background levels. The specific health consequences of long-term systemic microplastic exposure are not yet fully characterized, but preliminary evidence points toward inflammatory effects, endocrine disruption, oxidative stress, and the cardiovascular associations documented in the NEJM study. The difficulty is that virtually everyone alive today has measurable microplastic exposure, making controlled comparison populations essentially impossible.
Why it matters
The microplastic problem is structurally unlike most environmental contamination in that the source — plastic production — is diffuse, global, growing, and deeply embedded in virtually every supply chain. PCB contamination could be addressed by banning PCBs; lead in gasoline could be addressed by removing lead. Microplastic contamination cannot be meaningfully reversed without dramatically reducing plastic production globally, since the particles already distributed through the environment will not disappear on any human timescale and the rate of new production continues to exceed any conceivable cleanup rate. A 2023 study estimated that even if all plastic production stopped today, environmental microplastic concentrations would continue to rise for decades as existing macroplastics continue to fragment.
Recycling's failure as a solution is critical context for the microplastic problem. The plastics industry has promoted recycling as the primary response to plastic pollution for decades — including internal documents later revealed by investigative journalists showing that industry executives knew recycling was not technically or economically viable for most plastic types but promoted it to forestall production restrictions. Of the seven categories of plastic (labeled 1–7 on consumer products), only types 1 (PET) and 2 (HDPE) are widely recyclable at scale. Types 3–7 are rarely recycled and in many cases cannot be without producing toxic byproducts. The overall plastic recycling rate in the United States has hovered around 5–6% for years. The gap between what is labeled 'recyclable' and what is actually recycled is one of the most consequential consumer misconceptions in the history of environmental communication.
The regulatory response to microplastics has been slow and fragmented. The U.S. Microbead-Free Waters Act (2015) banned plastic microbeads in rinse-off personal care products — a meaningful but narrow step that addresses a small fraction of microplastic sources. No comprehensive federal regulation of microplastics in drinking water, food, or consumer products exists as of 2025. The EPA added microplastics to the Contaminant Candidate List — a research watchlist — but has not set drinking water standards. The European Union has moved further: it has proposed bans on intentionally added microplastics in products and is developing enforceable standards. The United Nations Global Plastics Treaty, under negotiation since 2022, aims to create the first international agreement addressing the full plastic lifecycle, but critical provisions on production caps remain contested by major petrochemical-producing nations.
The political economy of plastic regulation runs through the petrochemical industry, for which plastic production is a significant and growing profit center — particularly as climate policy threatens the use of fossil fuels for energy. As transportation electrification and renewable energy adoption reduce demand for oil and gas for combustion, petrochemical companies have announced plans to dramatically expand plastic production capacity to compensate. The American Chemistry Council, the industry's primary lobbying group, spent approximately $30 million on lobbying in 2023. This structural dynamic — an industry under pressure from climate policy pivoting toward increased plastic production as a business strategy — means that microplastic pollution is not simply an environmental problem but a downstream consequence of the politics of fossil fuel transition.
Sources & Further Reading
- Discovery and quantification of plastic particle pollution in human blood
- Microplastics and Nanoplastics in Atheromas and Cardiovascular Events
- Production, use, and fate of all plastics ever made
- Plastic & Climate: The Hidden Costs of a Plastic Planet
- The plastics industry knew its products were not recyclable — documents show it promoted recycling anyway