Is Your Coffee Cup Actually Made of Plastic?

A Brief Overview of Today’s Blog Post

Have you ever grabbed a coffee or tea on your way to school, practice, or work and thought about what the cup is made of? You might assume that because it is called a “paper cup,” it is mostly paper. However, there is something hidden inside many disposable paper cups that you probably cannot see: a thin layer of plastic.

This might sound strange. After all, the outside of the cup looks like paper. So why would there be plastic inside?

The Plastic Inside Your Cup

Most disposable paper cups cannot simply be made from paper because paper absorbs water. Imagine pouring your hot coffee into a regular piece of paper. Obviously, it would become soggy very quickly!

To prevent this, many disposable paper cups are covered on the inside with a very thin plastic lining. One common material used for this lining is polyethylene, also known as PE. This layer makes the cup waterproof and keeps your drink from leaking through the paper.

The problem is that this plastic lining is directly touching your drink.

A study published in the Journal of Hazardous Materials tested disposable paper cups by filling them with hot water. The researchers found that the plastic lining could deteriorate when exposed to hot water and that microplastic particles were released into the water. In one experiment, approximately 25,000 micron-sized particles were released into 100 milliliters of hot water after 15 minutes.

That number really shocked me.

Think about how long it takes to drink a cup of coffee. Maybe 10 minutes. Maybe 30 minutes. Maybe you are carrying it around all morning. The longer hot liquid sits inside the cup, the more time there is for the cup and its lining to interact with the drink.

Another study tested 90 batches of disposable cups under conditions meant to represent everyday use. Microplastic release was detected from all of the tested cup types, and higher temperatures increased the amount released.

But It Says “Paper”!

This is the part that I find most interesting.

When you hear “paper cup,” you probably picture something environmentally friendly. But a paper cup can still contain plastic. This does not mean every paper cup releases the same amount of microplastics, and it does not mean that drinking one cup of coffee is going to make you sick. Scientists are still researching exactly what these exposures mean for long-term human health.

However, I think it is important that we know what we are actually using.

There is another issue with tea. Some tea bags themselves can contain plastic materials. Research has found that certain plastic tea bags can release extremely large numbers of micro- and nanoplastic particles when they are placed in hot water.

So when you drink tea from a disposable cup with a plastic lining and a plastic-containing tea bag, there may be more than one plastic source involved.

What Can We Do?

I am not saying that you need to stop drinking coffee or tea! Instead, there are some really easy changes we can make.

If you are getting a hot drink, try bringing a reusable glass, ceramic, or stainless-steel cup. If you drink tea, look for loose-leaf tea or tea bags made from materials such as paper or cellulose rather than plastic.

The next time you pick up a “paper” cup, remember that what you see on the outside does not always tell the whole story. Sometimes, the biggest problems are the ones we can’t even see!