By Astrid Popovici

When most people think of plastic pollution, they imagine six-pack rings, bags, straws, or the pieces of trash you see on the side of the road.  But there’s also a more insidious type of plastic in the environment—microplastics, or plastic fragments less than 5 mm long.  That’s about the width of a pencil eraser or shorter.

Microplastics are everywhere: the ice cores of the arctic, the mangrove forests of Iran, and even the peak of Mount Everest.  They’re in our water, air, soil, and food. 

The average person eats and breathes in tens of thousands of microplastic particles per year.  Plastic particles run through our bloodstream, get entrapped in our stomach lining, and reach our organs.   A few weeks ago, scientists discovered microplastics in the placentas of unborn babies.

Microplastics enter the environment in a wide variety of ways, from cosmetic microbeads that miss water treatment filters, to synthetic fibers shed from clothing in the wash, to degraded bits of plastic bottles and bags.  The bulk of the environment’s microplastic pollution, around 80%, comes from textiles, vehicle tires, and city dust.

The prevalence of microplastics has negative effects on the environment and on human health.

In ocean ecosystems, small animals like zooplankton can mistake microplastic beads for food, causing them to fill up their stomachs with plastics and eventually starve.  And animals who eat microplastics and survive are still ingesting toxic pollutants that they pass up the food chain.

Microplastics can also harm our health.  Many of them carry toxic, carcinogenic, and endocrine-disrupting chemicals.  Polyvinyl chloride (PVC plastic) releases toxic chemicals when in contact with water.  Additionally, some of the chemical softeners used to make PVC can interfere with the body’s hormone production.  Even small concentrations of Bisphenol A (BPA)—a plastic that can be found in canned foods, receipts, feminine products, electronics, dental sealants, and more—can cause a range of health problems.  Concerningly, BPA is also an estrogen mimicker, meaning it can bind to estrogen receptors and modify the function of your hormones.

These effects might sound shocking, but it’s important to remember the “poison is in the dose.”  A 2019 review by the EU’s Scientific Advice Mechanism concluded that “microplastics and nanoplastics do not pose a widespread risk to humans or the environment, except in small pockets.”  However, this doesn’t mean increasing microplastic pollution shouldn’t concern us.  

In order to determine exactly how big of a problem microplastics are, we would need to look at the problem quantitatively.  Specifically, I’d like to see data on what concentration of microplastics people are being exposed to (e.g. the concentration in the bloodstream), and what concentrations would be needed to produce different types of negative side effects.  Unfortunately, I wasn’t able to find these numbers.

In any event, it’s probably wise to do what we can to avoid microplastics.  Choosing natural fibers over polyester, watching out for microplastics in cosmetics, and avoiding plastic packaging are good places to start.