What Is a Microplastic?

Microplastics are classified as primary (manufactured small, like microbeads in cosmetics and industrial pellets) or secondary (fragments from the breakdown of larger plastics by UV radiation, waves, and abrasion). They range from 5 mm down to nanoplastics (less than 1 micrometre). Since mass plastic production began in the 1950s, an estimated 8.3 billion tonnes have been produced, with about 6.3 billion tonnes becoming waste, much of which reaches the environment. Microplastics have been found in the Mariana Trench, Arctic sea ice, Mount Everest snow, rain, drinking water, food (especially seafood and salt), and human organs including blood, lungs, liver, and placenta. Their health effects are still being studied, but concerns include physical inflammation, chemical toxicity (plastics absorb and concentrate persistent organic pollutants), and potential endocrine disruption. A 2024 study found that people with microplastics in their carotid artery plaque had a 4.5 times higher risk of heart attack and stroke.