What are microplastics and nanoplastics?
Microplastics and nanoplastics are tiny fragments of plastic created as larger plastic waste breaks down over time. Microplastics are generally defined as pieces between 1 micrometre and 5 millimetres across — from roughly the size of a sesame seed down to specks too small to see. Nanoplastics are smaller again, under 1 micrometre, and invisible to the naked eye.
These particles are now found almost everywhere — in oceans, soil, air, food and drinking water — and their numbers in the environment are rising rapidly. We are exposed to them every day, and researchers have detected them in human tissue, including in the heart and in the fatty plaques that build up inside arteries.
This explainer focuses on what microplastics and nanoplastics may mean for heart and metabolic health — the areas the Baker Institute researches. It is not a complete account of every way plastics might affect the body; that broader picture is still being pieced together by scientists around the world.
How are we exposed to them?
Most exposure is thought to happen through what we eat, drink and breathe. Microplastics have been measured in tap and bottled water, seafood, salt and many packaged and processed foods, and they can be shed from plastic containers and packaging. Very small particles suspended in the air can also be inhaled.
Because plastic does not fully disappear — it simply breaks into ever-smaller pieces — these particles continue to accumulate in the environment, and everyday exposure is difficult to avoid entirely.
Why does it matter for the heart?
This is an emerging area of science, and much remains unknown. Studies have begun to link higher exposure to microplastics and nanoplastics with a greater risk of heart disease, heart attack and stroke — but exactly how these particles might cause harm has not yet been established.
One promising clue comes from the body's immune response. In the laboratory, Baker Institute researchers have observed immune cells called neutrophils treating microplastics as foreign invaders, much as they would an infection. Unable to destroy the particles, the immune cells can self-destruct, releasing a burst of DNA and proteins that injures nearby healthy cells. If this same process happens inside blood vessels, it may contribute to inflammation and plaque build-up that narrow arteries and raise the risk of heart attack, blood clots and stroke.
Pollution is already recognised as a major contributor to cardiovascular disease worldwide — linked to around one in six deaths globally. Yet plastic pollution has been largely missing from these estimates, simply because the data does not yet exist. Whether, and how much, plastics add to this burden is one of the key open questions researchers are now working to answer.
Can we reduce our exposure?
Because the health effects are still being studied, there are no official guidelines on "safe" levels of exposure, and it is not yet clear whether reducing exposure lowers any health risk. Even so, some simple, low-cost steps can cut down the amount of plastic you come into contact with:
- Avoid storing or heating food or drinks in plastic containers — use glass, ceramic or stainless steel instead.
- Reduce consumption of food and drinks packaged in plastic, including canned foods and takeaway cups (which often have a plastic lining).
- Minimise plastics when preparing and serving food — for example plastic chopping boards, utensils and straws.
- Choose natural fibres (such as cotton, wool and linen) over synthetic clothing where you can.
- Avoid plastic furnishings and synthetic lawn.
- Vacuum regularly to reduce plastic-containing household dust.
Whatever the eventual health findings, steps like these also bring wider environmental benefits.