Plastic is everywhere: in your home, in your coffee cup, on your streets, and in your oceans. But, despite its ubiquity, we don’t really know that much about it. You may have some vague suspicions that it’s not good to drink out of heated plastic containers or some inkling that it’s not good for the environment. Holding a piece of plastic, you might never know whether to recycle it or throw it in the trash, and those numbers molded into it are no real help. So, let’s get to the bottom of some of these questions.

To start: what do those numbers mean?

Many plastic materials you’ve encountered have a special symbol on them, called the ‘Resin Identification Code.’ This tells you what kind of plastic resin the item is made of, and it’s identified by a number inside of a three arrow triangle. Sometimes, the marking is really discreet, so you might not notice it. Other times, there is no Resin Identification Code, or there’s just a triangle with no number inside. But these numbers are important; they tell you a lot about the plastic, including its chemical composition, its toxicity, and its recyclability. The numbers range from 1-7, and some are more common than others. Here’s the breakdown:


PETE or PET - Polyethylene Terephthalate

Recyclable? Yes.

This plastic is usually transparent, and it’s used to hold carbonated beverages or water. It’s collected by most curbside recycling programs, and it can be broken down and turned into other plastic items.


High-Density Polyethylene (HDPE)

Recyclable? Yes.

This plastic is usually opaque, and it’s often found in milk jugs and shampoo bottles. It’s also typically collected by curbside programs, and it’s one of three plastics that’s considered safe because it has a low likelihood of leaching chemicals. Once it’s broken down, it can be turned into new plastic items.



Recyclable? No.

This plastic is found in food wrap, plumbing pipes, and detergent bottles. It’s rarely collected by curbside programs, and it has known toxic effects. It contains DEHA, which is a known carcinogen, and it may contain phthalates, which are linked to developmental issues and birth defects.


Low-Density Polyethylene

Recyclable? Mostly, no.

Plastic #4 is used to make bread bags, shopping bags, and frozen food packaging. It’s not typically accepted in most curbside programs, but in some places, they’re starting to accept it. This plastic is generally considered safe.


Polypropylene (PP)

Recyclable? Sometimes.

This plastic has a high heat tolerance, but, in some studies, it’s been shown to leach chemicals.


Polystyrene (PS)

Recyclable? Sometimes.

Also known as styrofoam, this plastic is known to leach styrene, which can damage people’s nervous systems.



Recyclable? No.

The #7 code identifies all items made from a combination of other plastic types.

Which types are safe, and which types should I avoid?

Considering toxicity alone, plastics 1, 2, 4, and 5 are believed to be relatively safer. Plastics 7, 3, and 6 are believed to be more toxic since they’re more likely to leach chemicals.

So, how is plastic actually recycled?

These days, there are 4 major plastic recycling methods. The first is called primary recycling, also known as ‘closed-loop’ recycling. This is when the original plastic item is reprocessed into the same item that it was before. In order to recycle this way, the plastic item needs to be in pristine condition, and its origins must be known.


The second is mechanical, or secondary, recycling. This process turns the original plastic item into a new, lower value item (downcycling). During the reprocessing, the plastic is melted into a polymer blend and then molded into a new item. The melting process causes polymer degradation, which is what accounts for the lower quality item that’s produced.


The third is chemical, or tertiary, recycling. In this process, the basic building blocks (polymers) of plastic are recovered. These are then used to create a new plastic item with the same material integrity. It works by subjecting multiple plastics to high temperatures in the presence of a catalyst. This is one of the most cutting-edge, promising forms of recycling, but it requires a lot of energy, so it’s usually only done at the industrial level. Nevertheless, scientists are trying to come up with more energy-efficient ways to use this recycling technology. Its main advantage is that it prevents us from having to separate different kinds of plastics at the recycling plant.

The last recycling method is incineration. In this process, the energy stored in the plastic item is recovered in the form of heat energy. Although there’s some energy return, recycling plastic waste, instead of incinerating it, is a much more energy-efficient option.

How much plastic do we actually recycle?

Allegedly, 9% of all plastic in North America is recycled. Some countries have reported even lower rates. Almost 80% of plastic ends up in landfills or as pollution.

Why isn’t more plastic being recycled?

Plastic recycling is very complicated. First of all, plastic production is outpacing almost any other man-made material on earth. Unsustainable and practically immeasurable amounts of plastic are manufactured every year. This makes it hard to control where it all ends up. And, since it’s such a lightweight material, it easily blows away, ending up as litter on land or in the ocean. In many poverty-stricken countries across the world, there aren’t community recycling programs, so a lot of plastic ends up as litter on the beaches or in the oceans.

Even when plastic is put into the recycling, it’s often diverted to a landfill later down the line. Certain items just aren’t accepted at recycling plants. Plastic bags, for example, are picked out, because they jam the machinery. But, in most recycling plants, plastics need to be separated and recycled by type. This is because each type of plastic has a different life cycle value based on its chemical composition. That is, some types can be recycled into new, high integrity items, while others can only be downcycled into low integrity items. Because of this, recycling plants can’t mix plastic types together. So, for all of those items out there made of mixed plastic materials, like cell phones, the whole item will simply be sent to the landfill, because it’s too time-consuming to sort through all of the different plastics at hand.

Another issue is that many plastic items don’t have a Resin Identification Code on them, like plastic cutlery from restaurants. These items are automatically removed from the recycling stream and sent to the landfill so that they don’t contaminate other plastics.

And, unfortunately, the majority of plastics can’t be turned into the same product again. Often, the only option is to down-cycle them or turn them into an inferior product. So, despite people’s efforts to recycle plastic, it’s often a lot of effort for a low-value product, which isn’t economical.

Nevertheless, plastic production is continuing at high rates, and so there needs to be a way to manage it all. Ideally, we’d want to stop manufacturing plastic and resort to using other materials, while recycling the plastic we already have.

Some moves are being made to reupholster or overhaul existing plastic waste management methods. For instance, some packaged product manufacturers are starting to use only one type of plastic in their packaging, so that sorting different plastics isn’t an issue for recycling plants.

Other companies have devised new methods of chemical breakdown that allow different types of plastic to be mixed together. Chemical recycling, for example, allows for all kinds of plastics to be thrown in together to create a new product, but it requires a lot of energy to do.

What can I do?

There are a number of things you can do to help alleviate the plastic waste management issue. Start at square one, and clean your plastics so that they can be recycled and don’t contaminate recycling loads.

From this point on, try to avoid buying plastic when you can. Try buying groceries that aren’t packaged in plastic wrapping. At the coffee shop, bring your own reusable cup. If you do buy products in plastic packaging, try to get products that have a clear Resin Identification Code on them, and make sure to recycle them properly.

Pay close attention to special recycling instructions for certain plastic items, like Ziploc bags, that need to be brought to your local grocery store.

If you want to go that extra step, try getting involved in your community or local government. Here is where you’ll have the potential to make a really big impact. If there are grassroots environmental action organizations in your community, join them and see what solutions they’re trying to come up with for plastic waste management.

If you have any extra tips on what to do to help manage plastic waste, tell us about them in the comments section below!

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