How is plastic made?

When plastic first entered the mass market in the 1950s, it was celebrated for making life more convenient and efficient. Today, it is nearly impossible to avoid. Almost all types of consumer products are either packaged in plastic, contain plastic or both. It makes our lives easier and more convenient, for cheap.

While it may seem cheap, our country and world’s addiction to plastic comes at a big environmental cost– from country-sized swirling gyres of plastic waste in our oceans and growing landfills in our country’s interior. This pollution is damaging our ecosystems and endangering public health.

Yet, despite the prevalence of plastics in modern life, most people don’t know how or where plastic is made. We put together this quick explainer on how plastic is produced and the impact it is having on the environment every step of the way.

Step one: Extraction

Over 99% of plastic is produced from fossil fuels. In the United States, gas is the main source of plastic production. Gas (and crude oil) extraction is itself a major source of carbon emissions, from the deforestation that occurs while clearing land to make room for drilling equipment to the methane emitted via flaring and leaking during the fracking process itself, a greenhouse gas 20 times more potent than carbon dioxide. In 2015, emissions from extraction and transport for plastic production were 9.5-10.5 million metric tons of CO2e in the U.S. alone, equivalent to the emissions of 2.1 million passenger cars driven for a year.

Outside of the United States, where oil is the primary feedstock for plastic production instead of gas, “approximately 108 million metric tons of CO2e per year are attributable to plastic production, mainly from extraction and refining” according to a comprehensive 2019 study from the Center for International Environmental Law. That’s the equivalent of over 25 million passenger vehicles being driven for a year.

Step Two: Refinement, cracking, polymerization (turning gas or oil into plastic)

The process of turning raw fossil fuels, like oil and gas, into a recognizable plastic form involves three main steps:

• Refinement: First, oil and gas are refined to obtain the specific chemicals needed to make plastic—hydrocarbons.
• Cracking: Large hydrocarbon molecules are then broken down into smaller molecules in a process called cracking. This is an energy-intensive process where steam cracker furnaces reach temperatures between 1380°F and 2,010°F to break the molecular bonds, resulting in smaller molecules like ethylene (from ethane) and propylene (from propane).
• Polymerization: These smaller molecules are subsequently reassembled into long chains, often with the aid of a catalyst, in a process called polymerization to produce plastics.

During processing, various additives may be mixed with the polymer to enhance properties such as strength, flexibility, color, and resistance to UV light or fire. Additives can include plasticizers, stabilizers, fillers, pigments, and flame retardants. The end result of polymerization typically creates a “resin,” which can take many different forms. Additives can be added at different stages within plastic production. When they are added partially depends upon what type of plastic is being produced.

There are over 10,000 different substances used within the different types of plastic; over 2,400 of them have been flagged as potentially concerning for persistence, bioaccumulation or toxicity by the European Union. 

These resins then undergo high temperatures, pressure, and cooling. Often, this process results in long, solid strands that are then cut into plastic pellets, or “nurdles.” Plastic pellets are normally less than 5 mm in size, and can be made from various types of plastic resins such as polyethylene, polypropylene, polystyrene, and more. But pellets are not the only form of pre-production microplastic– there are also flakes, powders, films and liquids, amongst others.

According to a report done by the Center for International Environmental Law, owing primarily to the amount of energy (and thus fossil fuel) needed to heat these furnaces, annual emissions from just two cracker facilities are the equivalent of 800,000 cars on the road, and these are only two of the hundreds of facilities in the US dedicated to producing plastic.

Step three: Production

Plastic pellets are the building blocks of plastic manufacturing. Plastic pellets are sent around the world to companies that manufacture plastic products– everything from single-use plastics like forks, take away containers, and grocery bags to durable plastic products such as toothbrushes, toys, and car bumpers. Their small size and light weight allows the plastic supply chain to span the globe, since they are cheap to manufacture and transport. 

These qualities are also what leads them to be spilled into the environment so easily. They are spilled –or dumped– at every stage within the plastic supply chain. They are spilled from the factories that manufacture them, during transportation, at distribution and export facilities, as well as into the oceans while they are being shipped around the world. In fact, plastic pellets are estimated to be the second-most common type of primary microplastic in the ocean by weight.

Once in the environment, it’s far too easy for a bird, fish or turtle to mistake these plastic pellets for food. If they eat enough plastic, they can starve to death. Plastic pellets can absorb toxic chemicals including DDT, PCBs, and mercury. These types of pollutants bioaccumulate, meaning they become more concentrated and more toxic as they move up the food chain. 

The plastic pellets that make it to their destination are melted down and then formed into specific shapes using techniques like injection molding, extrusion, or blow molding. This versatility allows them to be used in a wide range of products that we see in our everyday lives, from packaging and containers to automotive parts and electronics.

Step four: Disposal

The environmental impact of plastic doesn’t stop at the extraction, refinement, cracking, polymerization and production process. The disposal of plastic is a major challenge and has a big impact on climate change, our natural environment and public health. 

All of that plastic has to end up somewhere, and all of the pathways result in further climate emissions. Only 9% of plastic produced since 1950 has ended up recycled, while 12% has been incinerated. Though less carbon-intensive than incineration, recycling plastic requires burning fossil fuels to power recycling facility machinery, while incinerating plastic at incinerators and so-called “chemical recycling” facilities directly produces considerable amounts of greenhouse gasses. The climate impact of plastic waste incineration in the US is equivalent to “1.26 million passenger vehicles driven for one year, or more than half a billion gallons of gasoline consumed.” 

Finally, though currently less clearly defined than emissions from incineration, “disposing” of plastic waste by landfilling or, worse, open littering, produces carbon emissions over time due to exposure to solar radiation. 

Plastic does not decompose, but rather just breaks down into smaller bits of plastics- microplastics and nanoplastics. Microplastics are a widespread and severe environmental threat which is accumulating. They have been found just about everywhere- from isolated Rocky Mountain lakes to the deepest part of the ocean, as well as in our own bodies. 

Microplastics are considered an ‘emerging contaminant’ because many of the toxicological implications of these bits of plastic being able to enter our bloodstreams, food systems, and ecosystems are still not well studied. We know microplastics can affect the growth and health of plants and animals. Specifically, microplastics have been shown to stunt growth, cause inflammation, liver damage, even make changes in gene expression, amongst other effects. Also, it is not just the plastic particles that are a concern, but the chemicals that are used to make plastic can leach out into the environment and into our bodies.

Cumulative Impact

What is the cumulative impact of the plastic life-cycle on carbon emissions, and how does it square with the world’s imperative to reduce climate pollution as quickly as possible? The 2019 CIEL study estimated that, if growth in plastic production and incineration continues as planned by oil and gas companies, “their cumulative greenhouse gas emissions by 2050 will be over 56 gigatons CO2e, or between 10–13 percent of the total remaining carbon budget.”

As the world faces an unprecedented challenge in reducing greenhouse gas emissions, increased plastic production takes us in the exact wrong direction, continuing fossil fuel extraction and consumption and increasing emissions from the plastic production process at the very time we need to be reducing both carbon emissions and the amount of plastic in the world. 

On the bright side, reducing plastic production and turning off the plastic tap will bring many benefits for public health, wildlife and our climate. 

That’s why we’re going to continue our work to eliminate wasteful single-use plastics, get companies to reduce their use of plastic, pass common sense solutions like the Plastic Pellet Free Waters Act, and more, and help move our country beyond plastic.