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How Long Does It Take for Polystyrene Foam to Decompose?

Updated: Oct 8, 2023

how long does it take for styrofoam to decompose

While it has many uses, plastic foam’s negative impact on the environment is apparent. Despite this, several million tons of plastic foam is produced every year. Over the last few decades, there have been multiple debates about whether plastic foam, also known as polystyrene, is biodegradable or not. It has sparked numerous reports, prompting researchers to ask the all-important question; how long does polystyrene take to decompose, if ever? Estimates vary from a few years to a million years. As always, there are various environmental conditions to consider with each scenario.


It’s a daunting topic to unpack, but it’s absolutely crucial we do. In this article, we’ll unpack why plastic foam is bad and whether it truly decomposes or not. It’s time we understand the true impact of polystyrene foam.

What is plastic foam?

You’ve definitely come across plastic foam in your day-to-day life. It’s become so accepted as an everyday product that people forget to question its actual makeup.


Plastic foam is the colloquial name used for expanded polystyrene (EPS). In short, it’s a petroleum-based plastic manufactured from a styrene monomer using the polymerization process. Initially, this forms the translucent spherical beads we know as polystyrene. They’re about the size of a sugar granule. These granules, called nurdles, often make their way into our natural ecosystems, wreaking havoc on the environment even in their pre-production state.


For the pellets that remain in the production process, we then add a toxic combination of low heat, steam, and pentane gas to create the actual expansion, giving us plastic foam. Other names include EPS foam, polystyrene foam, and expanded polystyrene.


Polystyrene appears in all walks of life, from foam cups and foam coolers to EPS foam board, EPS foam sheets, and foam packaging. In the building world, styrofoam construction insulation foam is a common material, along with plastic foam insulation. There’s also extruded polystyrene insulation foam and expandable foam packaging. While they all have slightly different naming conventions, their impact is equally devastating.


From start to finish, plastic foam production relies on harsh chemicals. No matter what form it takes as an end product, it’s harmful to our environment.


Polystyrene vs Styrofoam: What’s the difference?

Styrofoam and polystyrene are two terms that are often used interchangeably, but they are actually slightly different. Polystyrene is a synthetic polymer made from monomer styrene. On the other hand, Styrofoam is a brand name for expanded polystyrene foam. The key difference between the two is that Styrofoam is a specific brand name of EPS, whereas polystyrene refers to the general polymer.

How long does polystyrene take to decompose?

One of polystyrene’s benefits is its strength and stability. It’s commonly used for food storage because it can repel water and resist acids, bases, salts, and other corrosive substances. It doesn’t grow mold or bacteria and can stay sanitary in storage. That’s why you’ll often see foam coolers, cups, and packaging. Polystyrene is renowned for its long shelf life, which is precisely the problem.

Because it is so chemically stable, once it’s in the environment, it will be there for generations in some shape or form. The Society of Environmental Journalists states that it requires about 500 years to decompose, and even then, we’re not sure what that really means.


While it resists most chemicals, plastic foam’s one weakness is sunlight. In a process called photodegradation, requiring consistent exposure to sunlight, polystyrene does start to break down, eventually forming a powdery substance. Unfortunately, many people mistake this process for decomposition or biodegradation. It’s far from that.


As the plastic foam becomes excessively hot, tiny amounts of styrene seep out of the plastic, contaminating the surrounding area. That’s where the real cost of plastic foam comes into play.


These tiny fragments disperse into the environment, whether it’s into our soil or our oceans. Given that it’s lightweight, polystyrene can travel vast distances, often accumulating in our waterways or shorelines. Unfortunately, much of it sinks to the bottom of the sea, polluting the actual seabed too. When fish eat these toxic materials, the chemicals bioaccumulate, making them harmful to the people who then consume the fish. It’s a vicious cycle.


What’s worse is the plastic foam shielded from the sunlight in our jam-packed landfills. It remains in the same state until it eventually reaches the light, only delaying the inevitable toxicity. Moreover, its porous nature allows it to absorb other carcinogenic pollutants, only contributing to the dangers of EPS foam.


Unfortunately, the harsh reality is that plastic foam doesn’t decompose. Yes, it breaks down into a state we can no longer see with the naked eye, but that doesn’t mean it’s gone, far from it.


Is polystyrene bad for the environment?

We now know that plastic foam is unlikely to decompose properly, only breaking down into smaller micro-plastic fragments. The fact that it never truly disappears is absolutely “bad” for the environment, but what are the other impacts to be aware of?

  1. It’s a Possible Carcinogen

In 2002 The International Agency for Research on Cancer established that styrene, one of plastic foam’s core elements, was a possible human carcinogen. In 2014, the National Toxicological Program report confirmed this, linking styrene to leukemia and lymphoma cancer. To be considered a carcinogen, a substance has to have the ability to damage or disrupt cellular metabolic processes. From a human perspective, this dramatically affects our day-to-day health.


2. Air Pollution From The Production Process

The chemicals used in the manufacturing process for plastic foam are toxic, contributing to air pollution and putting the workers at risk. One of the main ingredients in plastic foam is Benzene which is a volatile organic compound classified as a key pollutant by the EPA.

As if to rub salt in the wound, polystyrene is made with petroleum, a non-sustainable resource. Petroleum production creates its own devastation in air pollution, only adding fuel to the fire.


3. Harmful to wildlife


The microplastics that are formed when polystyrene breaks down persist in the environment for hundreds of years. Unfortunately, our wildlife is none the wiser. More often than not, they ingest microplastics simply by drinking water or munching on greenery. The ingestion of microplastics can have detrimental effects, including physical harm or even death.


Small animals such as fish and turtles can mistake microplastics for food, leading to blockages in their digestive system or malnutrition. Microplastics can also accumulate in larger animals that eat smaller ones, causing a buildup of toxins in their bodies that can have negative effects on their health.

The Life Cycle Initiative

As we can see from the harmful elements of polystyrene production from start to finish, understanding a product’s full lifecycle is critical. In 2002, UNEP joined forces with the Society of Environmental Toxicology and Chemistry (SETAC) to launch an international partnership designed to put life cycle thinking into practice. The Life Cycle Initiative focuses on a framework of programs that demand sustainable consumption and production patterns. It’s about spreading the idea of life cycle thinking and understanding the true impact a product has for years to come.

That’s where Cruz Foam comes in with its natural plastic foam alternative. Cruz Foam’s fully-compostable products are derived from all naturally occurring materials. Aptly described as “circular materials,” they genuinely model the ethos of life cycle thinking that’s paramount in today’s society. If this had been a priority in the past, plastic foam would never have existed.

The Takeaway

While the jury may be out for an exact amount of time, the unsettling truth is that polystyrene doesn’t decompose. It’s not a question about how long it takes but rather about understanding just how dangerous the cycle of plastic foam is. While sustainable material providers such as Cruz Foam have made positive advancements in this space, more businesses must start to harness life cycle thinking. We have to start operating beyond the here and now, understanding the actual timeline for the products we use in our day-to-day life.


Looking for a sustainable, circular packaging solution for your business? Contact Cruz Foam to learn more about how we can help.


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