Eternal Plastics

Sometimes there is nothing more refreshing than a cold drink. You walk into a restaurant, get your plastic cup of soda, and stab a plastic straw through the lid. The drink is gone in probably an hour at the most, but that cup and straw will be hanging around in a landfill or ocean long after that.

What is it?

What are these things made of that make them stick around for so long? Most drinking straws are made out of polypropylene, a commonly used polymer. A polymer is a very long chain of molecules all bonded together. Most plastics that you use are polymers. Polypropylene is made using propylene gas, a fuel made up of hydrogen and carbon atoms. The gas goes through a chemical reaction (polymerization), and a lot of the propylene molecules form one very long chain called polypropylene. This makes your drinking straws. Another polymer is polyethylene terephthalate. This is the plastic in soda bottles and is made of long chains of carbon, hydrogen, and oxygen atoms.

How do we use it?

Plastic has become a large part of our life ever since it came into popular use in the 1960s. It is used everywhere, from hospitals to shoes to food containers. It is inexpensive and easy to shape and use in a variety of ways. Medical use of plastic allows for making better artificial limbs. Sterile plastic packaging cuts down on the risk of infections. Plastic in the home keeps our houses at more reasonable temperatures and cuts down on energy costs. Using plastic to preserve food keeps it good and fresh for longer.

But with all this plastic use, where does it all go after we are done with it? Plastic can’t decompose like other natural materials. In the future, there will be a need to make better plastics and be more careful with how we use it.

Plastic syringes for medical use.Plastic syringes for medical use. Airman 1st Class Dillon Audit, United States Air Force

Where does it go?

So why can’t plastic break down, like dead leaves? That is because, unlike plastic, bacteria and other little organisms can eat and break down organic matter, such as leaves, and put it back into the soil. The environment does not naturally produce anything quite like plastic, so the bacteria and organisms do not have the correct body parts to be able to break down and digest plastic.

What happens to our plastic straws if they can’t be completely broken down? Do they just lay on the ground? If they did, we would notice! According to the Be Straw Free Campaign through the National Parks Service, Americans use enough plastic straws to fill up 125 school buses worth every day! That obviously means straws must do something. Well they do! Plastic can break down a little. If left outside, the ultraviolet rays from the Sun will weaken the plastic, and wind, or waves if in the ocean, will slowly break plastic into little pieces. More weather will make even smaller pieces until plastic becomes microplastic, which we can’t see. Unfortunately, these microscopic pieces of plastic look like delicious snacks to some creatures in the oceans. But plastic can’t be digested the way their normal food is, so often too much plastic in their stomachs will kill wildlife.

Eight plastic drinking straws.Plastic drinking straws. Public domain

What can we do?

With all of the plastic that humans make, use, and throw away, by 2050 it is estimated that there will be more plastic in the oceans than fish. But there are ways that we can help.

  • Don’t just throw it! About a third of the plastic we make and use ends up not in a recycling can, not even in a trash can, but in the ocean somewhere. Be responsible for the trash you make and dispose of it properly.
  • Reuse! Instead of using plastics straws or cups, opt for a reusable version, such as metal.  
  • Clean up! If you’re at the beach, pick up any trash or plastic you see lying around and dispose of it properly.
  • Look for more environmentally friendly plastics, such as biodegradable plastics.

Earth friendly labelEarth friendly label. Public domain.



National Oceanic and Atmospheric Administration. What We Know About: Plastic Marine Debris. Retrieved from https://marinedebris.noaa.gov/sites/default/files/publicatio....

National Park Service. The Be Straw Free Campaign. Retrieved from https://www.nps.gov/articles/straw-free.htm.

Wilson, L. 2014. The Global Plastic Breakdown: How Microplastics Are Shredding Ocean Health. National Oceanic and Atmospheric Administration. Retrieved from https://seagrant.noaa.gov/News/Article/ArtMID/1660/ArticleID....

Wolchover, N. 2011. Why Doesn't Plastic Biodegrade? Live Science. Retrieved from https://www.livescience.com/33085-petroleum-derived-plastic-....

World Economic Forum. 2016. The New Plastics Economy: Rethinking the future of Plastics. Retrieved from http://www3.weforum.org/docs/WEF_The_New_Plastics_Economy.pdf.

About the Author

Melanie Snier
Science Writing Intern

Melanie Snier is a science writing intern at the Smithsonian Science Education Center. A rising junior at Temple University, she is studying chemistry and education, with a minor in community development. Her plan is to become a high school chemistry teacher, and inspire students with her love of all things science!