Microplastics

What is microplastic pollution?

Microplastics are tiny plastic particles, typically defined by a size range of less than 5 mm, about the size of a grain of rice. Even smaller are nanoplastics, which are so minute they can pass through cellular membranes.

Unlike organic matter, plastic does not biodegrade. Instead, it degrades, breaking into smaller and smaller pieces while retaining its chemical identity. This has led to a reality where microplastic is everywhere—from microplastic in clouds and microplastic in rain to the most remote corners of the ocean.

Where does microplastic come from?

Understanding microplastic sources is key to stopping the flow. They generally come from:

• Synthetic clothing: Fabrics like acrylic, polyester and nylon—are made from plastic. Items such as fleece jackets, athletic clothing, and polyester blankets can shed up to 1,900 microfibers per laundry cycle. Once they flow out of washing machines, these fibers are small enough to pass through wastewater treatment systems and end up in the ocean.
• Consumer goods & packaging: Everyday plastic items—like single-use plastic water bottles, food wrappers, take-out containers, and plastic tea bags—become brittle over time and break apart into countless microplastic fragments.
• Microbeads: Small, plastic beads found in personal care products like face wash and toothpaste. Microbeads in these rinse-off products can go straight down the drain. Many microbeads are not captured by wastewater treatment plants and make their way to the ocean. Fortunately, the U.S and other countries have banned the use of microbeads in these types of products.
• Vehicle tires: Synthetic rubber tires erode on roads, contributing significantly to microplastic air pollution and toxic runoff into rivers and oceans.

Detection in the ocean and the food chain

In our ocean research alongside our technology and science partner, the Monterey Bay Aquarium Research Institute (MBARI), we used underwater robots to sample water in Monterey Bay, one of the most protected ocean areas in the world and a National Marine Sanctuary. What we found was sobering. Microplastics were present everywhere, from the surface to the seafloor—1,000 meters deep. The highest concentration wasn’t at the top. It was in the midwater, crucial habitat where most marine animals feed and where the marine food web comes together. 

Even more concerning, every single animal we sampled, from pelagic red crabs to giant larvaceans, contained microplastics. 

Environmental effects on marine life

When microplastics invade habitats, they inevitably end up in the stomachs of ocean animals. The impacts of microplastic consumption on wildlife are severe:

• Physical damage: Microplastic can block digestive tracts or give a false sense of fullness, leading to starvation. Or can cut organs and lead to internal bleeding. Recent research shows that ingesting even small amounts of plastic can be lethal:  in certain species, eating plastic equal to just a few sugar cubes can greatly increase the chance of death.
• Stunted growth: Studies show that crustaceans like lobsters and prawns eat less, grow less, and use energy less efficiently when exposed to microplastics.
• Reproductive issues: In oysters, microplastic can disrupt reproduction. A major study showed that oysters exposed to microplastics produced 38% fewer eggs. In fish, microplastic particles can cross the blood-brain barrier, causing structural damage to the brain and interfering with nerve signaling. This leads to altered predatory behavior, reduced fertility, and damage to the liver and gills
• Toxic transfer: Microplastic is a primary "vehicle" for transferring heavy metals and pesticides through the food chain, eventually reaching humans who consume contaminated seafood. Find our curriculum, Biomagnification in ocean food webs: Plastic pollution here.
• Disease increase: For corals, the impacts are especially severe—disease rates increase from 5 percent to as high as 89 percent when in contact with plastics.

Human health concerns

The microplastic problem isn't just an ocean issue; it directly affects human health. Tiny plastic particles and nanoplastics have permeated our daily environment. Studies show we are consuming microplastics through the food we eat, the bottled water we drink, and the air we breathe.

• Internal accumulation: Because of their microscopic size, these particles can move beyond the gut. Scientists have detected microplastics deep inside the human body, including within blood, lung tissue, and placentas.
• Brain concentration: A groundbreaking 2025 study found that microplastics selectively accumulate in the human brain at much higher concentrations than in the liver or kidneys, with levels appearing to increase over time.
• Cardiovascular risks: A landmark 2024 study published in the New England Journal of Medicine found that patients with microplastics in their carotid arteries—the major blood vessels that supply oxygen to the brain —had a significantly higher risk of heart attack, stroke, or death compared to those without them.
• Reproductive & developmental impacts: Research indicates that microplastics can cross the placental barrier and have been detected in reproductive organs. These particles often leach chemicals that act as endocrine disruptors, which are linked to hormonal imbalances and reproductive disorders.
• Respiratory stress: Inhaling airborne microfibers—especially from synthetic textiles—can lead to chronic inflammation in the lungs and has been associated with compromised lung function and respiratory complications.
• Toxic chemical exposure: Microplastics act as vehicles for harmful chemical additives like PFAS and phthalates. Once inside the body, these toxins can trigger inflammatory responses which increase the risk of cardiovascular diseases and disrupt hormonal regulation, causing an elevated risk of cancer.

An issue this large can feel overwhelming, but this is a problem we know the solution to. We must slow and reverse the growth of plastic production, especially single-use plastics. We are working at every level to turn the tide and you can too. 

Dive into solutions and strategies for reducing microplastic for reducing microplastic pollution and protecting our ocean.