Plastics: What Can Be Recycled, What Can’t?

What numbers of plastics are recyclable?

Can you trust the little triangle that symbolizes plastic is recyclable?

It is six o’clock at night, and you just finished your beef and broccoli from China Palace. Staring back at you on the table is the empty container that once held your dinner. It is made of plastic, so you recycle it, right? After rinsing it off you scour its surface for the little triangle made of arrows and see that it has a small “5” within it. Recyclable! You toss it in the recycling bin and forget about it. 

Later that week when the trash truck comes, the workers see the container in your recycling bin next to the garbage can, pause a moment, and throw it in with the rest of the haul on its way to the landfill.

What’s recyclable and what’s not? Good question, and there’s no absolute answer. But we’ll try to set you straight as much as possible, because we know most people want to do the right thing, given the outrageous amount of plastic even the most environmentally conscious among us are bombarded with at every turn. 

A caution: Clearly, recycling is not the answer to the plastic crisis. The answer is elimination of 90 percent of the plastic, that is, eliminating most plastic manufacturing and use, especially in packaging, construction, and transportation. But for now, we want to make sure that those who want to recycle can do so knowing that what they try to recycle will actually be recycled and reused, not thrown in the landfill (whence it might end up traveling via waterways to the sea). 

Most recyclable plastic has a symbol on it that designates it as recyclable. However, not all plastics are created equal, and some cannot be recycled with other plastics. The plastics are  coded #1 through #7 and have various levels of recyclability. 

First, the good news: Plastics marked #1 (polyethylene terephthalate, or PET) and #2 (high-density polyethylene, or HDPE) are accepted by almost all recycling plants in the United States. Water bottles and salad dressing bottles are often made of PET, whereas many milk jugs and shampoo bottles are made of HDPE. 

Now for the bad news: Most other common plastics require specific factories and processes to be recycled and will not be accepted by most recyclers — so they end up in landfills or incinerators, despite people’s desire to recycle them.

Recycling PET is fairly simple, as it needs only to be washed and melted before being reformed. 

HDPE requires more work, as after being washed it needs to be refined using near-infrared radiation and other techniques before being shredded and melted for reuse. 

Polyvinyl chloride, or PVC or vinyl (#3), recycling is far more involved, as it is a polymer of several types of plastic that can contaminate batches of other plastics such as PET and HDPE. PVC, cheap and durable, is often used in plumbing pipes, flooring, house siding, electrical wires insulation, window and door frames, shower curtains, gutters, and downspouts. Because it’s hard to recycle, it is most commonly incinerated, but, known for its flame resistance, PVC can smolder unnoticed and release extremely toxic gases that endanger those in surrounding communities as well as those nearby. It contains or releases such dangerous chemicals as dioxins — the world’s most dangerous human-made carcinogen — as well as phthalates, vinyl chloride, ethylene dichloride, lead, cadmium, and organotins. As noted by the Center for Health, Environment, and Justice, “There’s no safe way to manufacture, use, or dispose of PVC products.” (Some places once used a process called Vinyloop, which could separate PVC into its base components, but it failed to meet European Union standards and is no longer used for PVC recycling.)

Low-density polyethylene, or LDPE (#4), can be recycled in a similar fashion to HDPE. LDPE can be found in household objects such as bread bags, shrink wrap, those dreaded six-pack can rings, and some food container lids. LDPE is a very flexible plastic known for its chemical resistance and waterproofing capabilities. Because of this, the soft plastic has become widely used. It cannot be recycled with HDPE as it requires different machinery to be processed correctly. 

Polypropylene (#5) is typically used in plastic containers, reusable water bottles, and bottle caps. One reason polypropylene is popular is because it can be injection molded to form complex shapes. It is often melted at extreme heats and reprocessed into pellets to be reshaped. In order to be melted down, the furnaces have to reach 4640°F (2400°C), right around half the surface temperature of the sun. Due to the incredibly high heats required to melt polypropylene, it is not often accepted. 

Polystyrene (#6) is generally unrecyclable and mostly ends up in landfills. It is primarily found in the form of Styrofoam and is usually used in packing and in take-home containers from restaurants in the United States. There are many restrictions on polystyrene recycling, and thus it’s difficult to dispose of properly. However, in properly equipped factories, it could be melted down and turned into granules to be used in other products. 

All other types of plastics are marked as a catch-all #7 (if they are marked at all) and include plastics like bisphenol A (BPA, exposure to which is a health risk discussed in more detail in the main story) polycarbonate, and polylactic acid (PLA). Items made of these types of plastics include Nalgene water bottles, some food containers, baking bags, cups and plates. Products stamped with a 7 are often made of multiple plastic types and thus simply cannot be easily recycled, although others are recyclable using a labor-intensive process. Some larger recycling centers accept and sort through them to determine recyclability

Despite being marked with a symbol that is the very emblem of recyclability, most plastics that bear this symbol are either not recyclable or will not be recycled by municipalities. 

Now that you know the differences between the recycling codes, look up which are allowed to be recycled in your community. Avoid contaminating an entire batch of recyclables by including unwashed or wrong-type materials. Even though recycling isn’t the answer to the scourge of plastics, it’s absolutely critical to do it as diligently and carefully as possible to slow the growth of the plastic mountains on land and “islands” in the seas. It’s also important to regularly remind retailers that you don’t need or want items you purchase to be encased in plastic; the more they hear this complaint, the more likely they are to pressure distributors to eliminate wasteful plastic packaging.

North Americans: To find your community’s guidelines on recyclables, do a web search for your city or county and state or province name and “waste management and recycling.” If, as is often the case, the website doesn’t yield much information, call the city or county offices to get a specific list of what can and cannot be recycled and instructions on how, when, and where to leave it. 



Alex Hartzog, who also took the photos for this article, was the summer 2021 SCNCC writing and reporting intern through the Park Center for Independent Media, during which time he was deeply immersed in research on plastic pollution. He will receive his degree in journalism from Ithaca College in Ithaca, New York, USA, in December 2021.

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