Today, we dive into the subject of microplastics in this first of a three-part series taking an initial look at the scientific understanding and extent of the problem. In part two, we’ll cover how plastics are being tracked, and finally, in part three, we’ll describe hopeful efforts bringing about change.

The need hasn’t been greater for a better understanding of how microplastics may be affecting us and the environment. Some say we are in a race against time to stem harsher consequences. Hundreds of millions of tons of plastics are produced each year, and of that, close to 2 million metric tons goes into the ocean, one of the greatest modern-day threats to marine ecosystems.

In the scheme of things, our knowledge of microplastics — plastic debris about the size of a sesame seed — and their tinier cousins, nanoplastics, of less than 0.1 micron — isn’t extensive. Understanding the impact of the proliferation of plastic in our ecosystem is in its formative years. The sources of these prevalent particles range from pellets used in manufacturing goods to larger plastics deteriorating in the sun.

What is expanding are the places where plastics in all their various sizes are found. No longer confined to landfills, plastics have been documented along highways, in the Arctic, inside glaciers, in the deepest part of the ocean, in our bodies, and even in the air. Yes, we’re literally breathing them in.

Inside our bodies, researchers have found plastic in organs, arteries, placenta, and human waste. And underlying the spread of microplastic is the fact that most of them are non-biodegradable and can stick around for centuries. The longer they persist, scientists have observed, the insidiously smaller they become. Definitive knowledge about their end-of-life fate is lacking.

“None of the commonly used plastics are biodegradable. As a result, they accumulate, rather than decompose, in landfills or in the natural environment,” as noted in a 2017 Science.org article chronicling the fate of all plastics ever made. “The same properties that make plastics so versatile in innumerable applications—durability and resistance to degradation—make these materials difficult or impossible for nature to assimilate.”

How microplastics affect human health is a chief concern. Several factors complicate knowing the health impacts of microplastics because of the material’s inherent complexities:

• There’s no single kind of microplastic
• They come in many shapes and sizes — spheres, fragments, and fibers
• Other chemicals additives are often added to them
• Microplastics can carry “hitchhikers” such as viruses

Because of these variables, designing the right kind of research about the potential harm of microplastics faces many challenges, and consequently, evidence pointing to specific harm from microplastics is modest or just now emerging.

Sherri Mason, a scientist with Penn State, told The Washington Post that over the next decade, better data will come to light, “but we’ll never have all the answers.” Techniques to measure microplastic, detect the kinds of polymers in them, and know how those chemicals and polymers act under certain conditions in nature and in our bodies will be part of the investigations.

Grabbing fewer headlines, a third area of concern about plastics is how they affect our climate. Most plastics originate from greenhouse gas-emitting (GHG) fossil fuels. Transporting plastics causes CO₂ emissions — before, during, and after their use. In its afterlife, incinerated plastic releases chemicals that contribute to climate change. If landfilled, plastic can emit methane, a potent GHG, as it breaks down.

Where does that leave us? In the second blog of this three-part series, we delve into efforts that are underway to keep tabs on microplastics in the environment and support change.