Styrofoam Facts — Why You May Want To Bring Your Own Cup

April 10, 2019

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Issue Backgrounder: Styrofoam Facts — Why You May Want To Bring Your Own Cup

By Joseph A. Davis

Styrofoam may be good for keeping coffee hot, but it is also good for stirring up political controversy. That’s because many of the things that make styrofoam good for consumers and commerce also make it bad for the environment.

There is much for people (and journalists) to understand about the technical and environmental aspects of the plastic. This month’s Backgrounder gives this long-troubling pollution source a deeper look. Plus, for the latest developments, explore recent headlines on styrofoam and read this TipSheet.


What is styrofoam?

First, we are duty-bound to warn you that “Styrofoam“ is, legally, a trademarked name for a particular Dow product typically used as a building material.

But the word styrofoam is widely used in conversation and media when referring to expanded polystyrene foam — which you may use in that disposable cup or as “peanuts” to pack fragile things for shipping.

Technical and legal sticklers may prefer the term expanded polystyrene, or EPS. The AP Stylebook settles for “plastic foam.”


Polystyrene is the name for

a whole family of plastics …

but the foam forms have

disproportional environmental impact.


Polystyrene is the name for a whole family of plastics, and in various forms they are used for many other things than foam. This backgrounder will focus on the foam forms, since they have disproportional environmental impact.

Polystyrene was discovered way back in 1839, was manufactured starting in the 1930s, then was first foamed in the 1940s, and first sold as coffee cups in the 1960s.

The term polystyrene refers to a polymer (long chain molecule) of the monomer (smaller molecule) styrene. Various gases have been used to blow it up into foam form. The raw materials from which it is made are hydrocarbons (ethylene and benzene) that come from petroleum and natural gas.

Polystyrene is a plastic — meaning that when it is heated, it takes a liquid form that can be molded, shaped or extruded. And then when cooled again to room temperature, it becomes solid. This is what makes it useful for commercial products.

In manufacturing, polystyrene usually starts as small beads. These dense, hard beads are softened by heat and expanded using things like steam and blowing agents, becoming much larger and less dense beads.

During expansion, the beads become skinned cells that may be as little as 3 percent as heavy as the original bead, with most of the volume being gas. These expanded cells may then be formed and bonded into useful shapes.

In finished form, EPS has a number of useful properties. It insulates; that is, it slows heat transmission. It absorbs shock. It is not dissolved by common liquids like water, serving as a barrier.

So it may be great for boiling hot coffee, picnic coolers, bicycle helmets, home insulation, packing materials, restaurant carry-out containers and egg cartons.

This is not to say that styrofoam is the only, or the best, material for these applications. We love a radio-video piece by Jacob Fenston and Tyrone Turner of WAMU, who showed that styrofoam egg cartons are not necessarily better at protecting eggs.


So what is the problem with styrofoam?

Why, then, is styrofoam of environmental concern? Simply put, it gets into the ocean and other environmental realms, and it does not go away for a very, very long time.

Worse yet, it disassembles into its component little cells, which float away and can be consumed by aquatic and marine creatures.

A lot of styrofoam waste does go into landfills (better than the ocean, but hardly great). But styrofoam is notoriously hard to recycle, and is not accepted by most municipal recycling programs.

Styrofoam is not exactly a, um, health food either. If your kid swallowed a piece of it, it probably would not hurt them, as long as it passed through. But the styrene monomer from which it is made is suspected of causing cancer and other health problems, and miniscule amounts of styrene could leach into your hot coffee.

Styrofoam can break down into polystyrene beads, which can be consumed by aquatic and marine creatures. Photo: Andrew Moreton, Flickr Creative Commons. Click to enlarge.

Potential releases of styrene and its precursors during manufacture could also present problems.

Will use of styrofoam expose you to styrene in worrisome amounts? That’s the question.

For the occasional coffee, it may not be a big concern. But certain conditions cause polystyrene to break down chemically and possibly leach styrene.

Heat and hot liquids may be a problem. And microwaving your styrofoam may be iffy. There’s also acid (lemon in your tea?), as well as red wine and some oily foods.

There are also a number of solvents (e.g., acetone nail polish remover and gasoline) that can break down polystyrene.

A 1986 U.S. Environmental Protection Agency study found styrene residues, however infinitesimal, in 100 percent of the human fat tissue samples taken. Styrene toxicity may be much greater for people exposed occupationally or via air pollution.

Cells from broken-down styrofoam find their way into streams, lakes and oceans. There, they may be consumed by fish and other marine and aquatic animals, who easily mistake them for food.

This is not good for the sea creatures (they may choke or starve), nor for the creatures who consume them — which may ultimately include us humans.

Another environmental issue may arise from the blowing agents used to foam EPS. In the past, some fluorinated hydrocarbon gases were used because of their stability. More recently, their effects on the ozone layer or global warming have prompted a shift to substitutes.   


The fate of styrofoam waste

So let’s imagine that your foam coffee cup goes into a trash can and ends up buried in a legally permitted municipal landfill. It may still be a problem there.

One issue is volume. Styrofoam takes up a lot of room per unit of weight. Remember that as foam it has been expanded 40-to-80 times its original volume. A lot of landfills are running out of room.


One common estimate is that styrofoam

can take up 30 percent of the space in some

landfills. And some estimates put the lifespan

of styrofoam in a landfill around 500 years.


One common estimate is that styrofoam can take up 30 percent of the space in some landfills. Once in the landfill, it does not decompose quickly. Some estimates put the lifespan of styrofoam in a landfill around 500 years, and some put it way beyond that.

Of course, some fraction of all discarded styrofoam does not go into landfills. Some estimate that fraction at 20 percent, at least in the United States. A lot of that is just littered around the landscape, and a lot of that ends up in water. It does not biodegrade. It is chemically stable, and bacteria and microorganisms do not feed on it.

It is common wisdom that styrofoam can not be recycled, which is not true in a very technical sense. It is true that the vast majority of municipal recycling programs will not accept it. But there are a few facilities that will take it.

One reason is that most styrofoam waste (think carryout food containers) is not clean and cannot be easily cleaned. Recycling operations can’t handle the contaminated waste. A second important reason is that nobody can make any money recycling styrofoam.

This is where you have to distinguish styrofoam (EPS) from polystyrene.

Ordinary hard, unexpanded, polystyrene is common in commercial use — an example may be that yogurt or sour cream container in your refrigerator. It will have the triangular recyclable logo on it and the number 6, meaning polystyrene. Clean these and recycle them. Most cities will take them.

Joseph A. Davis is a freelance writer/editor in Washington, D.C. who has been writing about the environment since 1976. He writes SEJournal Online's Issue Backgrounders and TipSheet columns, directs SEJ's WatchDog Project and writes WatchDog Tipsheet and also compiles SEJ's daily news headlines, EJToday.

* From the weekly news magazine SEJournal Online, Vol. 4, No. 15. Content from each new issue of SEJournal Online is available to the public via the SEJournal Online main page. Subscribe to the e-newsletter here. And see past issues of the SEJournal archived here.

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