Sustainability of Expanded Polystyrene (EPS) Foam Products

Contents

Abstract

Introduction

Definition of Sustainability

Context & Importance of the EPS foam problem

Chemical Composition of EPS foam

Material Property of Interest

Association to Sustainability Definition

Life Cycle Analysis of Styrofoam

Toxicity Effects on Humans & Undesirable Environmental Impacts

Toxic Health Effects on Humans

Undesirable Environment Impacts

Management of Styrofoam

Conclusion

References

 Styrofoam is a term people often misuse when referring to the light and white disposable items that are used to hold food and beverages. However, Styrofoam was invented by The Dow Chemical Company and is known for its usage for thermal insulation purposes. Hence, in this paper the term Expanded Polystyrene (EPS) foam will be used instead (The Dow Chemical Company, 2008).

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Through research and looking into how its usage and post-use affects the human population and the environment, it was found that the social and environmental costs outweigh the economic benefits. This paper also explores the management of EPS foam and found that biodegradation of EPS foam can be done with the use of heat and the aid of bacteria or through mealworms.

Polystyrene, from which EPS foam is made, can serve various purposes such as “peanuts”, or as rigid panels. This paper will focus specifically on packaging with EPS which represents more than one-third of the global demand for polystyrene (Smock, 2014). Single-use EPS foam products are unsustainable as they are often thrown away and left to accumulate in landfills or even incinerated, producing harmful chemicals such as carbon monoxide. Every year, more than 14 million tons of foam cups are produced around the world. The production process not only affects humans, but it also affects the environment due to improper waste handling.

 This paper highlights the effects that EPS foam products, pre and post consumption, have on humans and the environment. It will also focus on the alternatives to throwing foam products into the trash bins and incinerating foam.

 This paper begins by briefly discussing the definition of sustainability, the context and importance of the EPS foam problem, the chemical composition of EPS foam, its material properties, and the life cycle analysis of EPS foam.

There are many different definitions of sustainability, and it is often hard to settle on one (Owens & Legere, 2015). In this case, sustainability is defined as the constant use and production of a material, that is fuelled by consumer demand due to its low cost and does not harm the surrounding environment and its occupants (no source).

The first prominent issue is that foam manufacturers are the 5th largest producer of toxic waste in the United States of America (USA) in 1986 (Collier County, n.d.). More than 14 million tons of EPS foam are produced around the world every year. In the USA alone, 3 million tons are produced (Solyom, n.d.).

Secondly, foam products after their use, contribute to White Pollution. White Pollution is the solid waste produced from the usage of various types of life plastic products. (OnGreenGo Solutions, n.d.). The White Pollution results in an unaesthetically pleasing landscape as plastic products fill the streets and oceans as shown in Figure 1.

Figure 1: Contribution of Styrofoam Products to White Pollution (Global Times, 2016)

  According to an article written by Griffin and Wilkins, an Environmental Communication Consultant and Marine Conservation Enthusiast, respectively, plastics and foam comprises 90% of all marine debris. This was found by conducting ocean and coastal surveys. In addition, according to the Los Angeles Times, foam is also the second most found beach debris in Southern California (Andersen, 2017). The effects of this will be discussed in the subsequent topics.

The next biggest impact of foam is land pollution. In one year, it was found that 25 billion foam cups are thrown away and out of this 25 billion, 2.3 million tons end up in landfills (Solyom, n.d.). With landfill space decreasing at a rapid rate, there may not be enough space for other trash if EPS foam products continue to be thrown away.

Lastly, on a more personal level, when EPS foam products are heated at 70°C, it causes the leaching of styrene (Ahmad & Bajahlan, 2006). This not only applies to foam cups and containers, but it also applies to EPS foam water bottles. With styrene classified as a human carcinogen (International Agency for Research on Cancer (IRAC), 2002), the effects on humans due to the leaching may be harmful if exposed for a long period of time.

The chemical formula of EPS foam is (C8H8)n. It is made up of water (H2O), styrene (C8H8), ethylene (C2H4), benzene (C6H6), aluminium chloride (AlCl3), and pentane (C5H12), which is a blowing or expanding agent (Chandra, Kohn, Pawlitz, & Powell, 2016).

To manufacture EPS foam, it goes through a series of processes such as dehydrogenation and polymerization. The manufacturing process to produce EPS foam is shown in Table 1 below.

Inputs

Outputs

Ethylene + Benzene + Aluminium Chloride (Catalyst)

Ethylbenzene

Ethylbenzene  Dehydrogenated at 600-650°C

Styrene

Styrene  Polymerisation at 100°C

Polystyrene

Polystyrene + Pentane + Water for cooling

EPS foam

(Advameg, n.d.) 

Table 1: Manufacturing Process

To illustrate the bonds formed after polymerisation, it is shown in Figure 2 below.

Figure 2: Styrene monomers polymerised to for polystyrene (Jansen, 2016)

While most production of materials such as aluminium and steel produces waste materials, for EPS foam, no solid waste is generated (The BPF EPS Group). Any waste generated will be put back in the process and continue to be used.

EPS has different material properties such as compressive strength, tensile strength, and thermal insulation (EPS Industry Alliance, 2016). However, in this paper, the focus will be on its density. As the name suggests, and explained from the manufacturing process, EPS foam is made up of 95 percent air (Chandra, Kohn, Pawlitz, & Powell, 2016). The low density of air in EPS foam contributes to its lightweight nature as well as making it a good insulator. Since it is also easily produced, the cost of production declines, therefore making it an inexpensive material. According to research, the resale price of foam products used to be 20 cents per pound and has now decreased to 6 cents per pound, making it even cheaper and easier to purchase (Chandra, Kohn, Pawlitz, & Powell, 2016).

Association to Sustainability Definition

As mentioned in the beginning, sustainability in this paper is defined as the constant use and production of a material, that is fuelled by consumer demand due to its low cost and does not harm the surrounding environment and its occupants. Due to its inexpensive retail price, businesses such as food and drinks vendors continue to purchase and use them as single-use products fuelling greater demand. As such, it is sustainable in the economic sense but unsustainable in environmental sense.

The life cycle of EPS foam starts from its production and moves on to its usage and lastly its post-use management. According to World Centric, which came up with some calculations, assuming that an average person uses five disposable items per day for a year, and that the average household uses 29.19 kWh of energy per day, if a person chooses to use only foam items, at the end of one year, he would have consumed 191.11 kWh of energy, released 95.81 pounds of CO2 & used 254.59 gallons of water (World Centric, n.d.). The total energy produced is enough to power a household for 6.55 days.

After its usage, people throw them away as most recycling plants do not take in type 6 plastics under which foam products are categorised (Louie, 2015). However, if people do choose to recycle them, for recycling to take place, according to a blog from Columbia University, the EPS foam must be completely free of any food or liquid residue. As such, this makes it hard to recycle as food residues are often trapped in the porous holes of the foam containers. Its brittleness also makes it hard for recycling plants to clean and remove as they may break into pieces (Louie, 2015). Therefore, EPS foam cups and containers either end up in landfills or incinerators (Chandra, Kohn, Pawlitz, & Powell, 2016).

When EPS foam is incinerated, it can go one of two ways. The first would be to incinerate it at over 1000°C. when it is incinerated at such high heat, it produces clean by-products such as CO2, water, soot, and heat (Derrick, 2010). However, if EPS foam is incinerated at a temperature of up to 900°C, which is usually the case for a modern incinerator, it releases over 90 dangerous compounds such as carbon monoxide, alkyl benzenes, and benzo[ghi]perylene (Derrick, 2010).

Toxic Health Effects on Humans

According to the National Toxicology Program, exposure to styrene increases the risk of cancer as styrene is listed as one of the human carcinogens (National Toxicology Program, 2016). In addition, workers in EPS foam manufacturing plants run the risk of developing illnesses such as lung tumours and lymphoma. This is because they are constantly exposed to harmful chemicals like styrene and toluene among others (Clean Water Action, 2009).

Besides cancer, long term exposure of styrene from the production of EPS foam also causes other negative health impacts. For instance, fatigue, central nervous system dysfunctions, and, chromosol abnormalities (Members of Congress of the United States, 2011). Recognising the negative health impacts, the Congress of the U.S.A wrote a letter to ban the use of EPS foam in the House of Representatives cafeteria.

Undesirable Environment Impacts

Besides the toxic health effects on humans, the environment suffers much more. EPS foam products take 500 years to break down (Collier County, n.d.). Furthermore, as they remain in landfills, leaching of styrene can also occur which seeps into the groundwater, thus affecting water quality (Members of Congress of the United States, 2011).

Since EPS foam products take half a millennium to break down and are lightweight in nature, they not only pollute the environment but also affect the ecosystem. Its lightweight nature allows for it to float on the sea. As a result, animals such as birds and fish can mistake them for food. The Styrofoam accumulates in their digestive tract making the animal feels full. As such, they stop feeding and eventually die from intestinal blockage or starvation (Griffin & Wilkins, 2018).

Another environmental impact is air pollution. As aforementioned, incinerating EPS foam at a temperature of up to 900°C can produce hazardous gas. This can affect the air quality of communities living around the incineration plants which can lead to adverse health effects and costs. (Members of Congress of the United States, 2011).

There are four ways that EPS foam is currently managed, with the most common ones being incineration, throwing them into the landfill, and recycling. However, the problem with incineration is the production of harmful chemicals if it is not incinerated at a high enough temperature. Hence, EPS foam products usually go to landfills once disposed wherein they fill up 25 to 30 percent of landfill space around the world (Collier County, n.d.). In addition, according to Collier County, approximately 1,369 tons of EPS are buried into the U.S. landfills daily.

That being said, countries have tried to implement recycling programs to recycle EPS foam. For instance, in 2013, the City of Montreal and the plastic industry piloted a one-year recycling program to take in EPS foam products (CBC News, 2013). With the help of this pilot project, Montrealers can bring EPS foam and other polystyrene products to the Écocentre in Lasalle. However, the rate for recycling EPS foam is still on the low side as it is uneconomical due to its lightweight nature where the transport costs outweighs the benefits it gets from recycling (CBC News, 2013). According to Clean Water Action, which is a non-profit organisation based in California, only 0.8 percent out of the 377,580 tons of polystyrene produced is recycled. Out of that 0.8 percent, only 0.2 percent of polystyrene food service packaging is being recycled (Clean Water Action, 2009).

In order to combat this, Polystyvert Inc., a recycling centre in Montreal, claims to have developed the first technology in the world to recycle polystyrene by dissolving it using a chemical process (Serebrin, 2018). The article from the Montreal Gazette stated that by dissolving the EPS foam, it tackles the issue of costly transportation. This method removes air in the EPS foam therefore allowing it to be transported more easily, reducing transport cost (Serebrin, 2018). Hence, in future years to come, recycling number 6 plastics may be more cost-effective.

There has also been research on biodegrading EPS foam. One of the methods include the use of thermal degradation with the aid of bacteria in order to produce usable by-products. According to the journal Science Direct, this is a two-step process. The first being to liquify the polystyrene by heating it at approximately 240°C, which is the melting point of polystyrene, turning it into styrene monomers. Since viscosity was reduced, this allowed the bacteria greater access for degradation which is the second step of the process. The preferred choice of bacteria to break down the polystyrene is P. putida. However, using this bacterium may produce styrene gas but this can be easily overcome using a yeast fungus, which can purify and treat the air polluted with styrene (Savoldelli, Tomback, & Savoldelli, 2017).

The other method is the use of mealworms. An experiment was done by Yang et al. for the 8th International Conference on Future Environment and Energy (ICFEE 2018) where mealworms were used for biodegradation and bioremediation of plastic pollutants. In the experiment, different batches of yellow mealworms from Harbin, China and California, U.S.A were fed with EPS foam (5.8g) as their only source of food for a month. At the end of a month, it was found that the mealworms (500 in an incubator) had consumed 31.0 ± 1.7% of EPS foam. The survival rate (SR) found was approximately 81.3 ± 2.5% and 86.7 ± 3.3% respectively and there was no significant difference between the SR of foam-feeding mealworms and conventional diet (bran)-feeding mealworms (Yang, et al., 2018). Hence, this indicated that EPS foam-feeding can be digested by the mealworms and be exploited as a source of life-sustaining energy.

This paper has highlighted the problems and negative impacts that EPS foam has on the human population and environment. In addition, it has also highlighted the various ways that EPS foam can be managed with a larger focus on recycling efforts and biodegradation. Currently, more efforts need to be focused on reducing the usage of EPS as a single-use product so that it can lower quantity demanded and in turn lower supply. Furthermore, while the production of EPS foam does not produce any solid waste and is relatively inexpensive to produce, the social and environmental cost far outweighs the economic cost. Therefore, it is not sustainable.

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