Plastic: It’s Not All the Same

The Basics On 7 Common Types of Plastic

In our continuing effort to provide educational resources on plastic pollution and sustainability, we thought we would address one of the most common questions we receive: Isn’t plastic all the same? In short … no. 

However, it’s understandable that many people make the assumption that it’s one material, all the same from top to bottom. In fact, there are hundreds of types of plastic (also called polymers), but only a handful that we interact with on a regular basis. 

While we believe that plastic alternatives are a must, and support initiatives to develop them, the reality is that plastic is here and will be for some time. Therefore, I say let’s try to better understand it, rather than ignore it or simply bash it. In the end, not all plastic is bad. Humanity has certainly benefited from it in some ways and you can even make arguments that support that it’s also been beneficial to the environment – although in very specific examples. 

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Having knowledge of the different types of plastic is critical to understanding the complexity of recycling, upcycling and the health factors associated with plastic. But the key word there is “complexity.” It’s a huge topic, so this article is just a starting point, meant to be a basic introduction for those that have little to no knowledge, not a comprehensive look for those already in the know. 

The first step is to simply know the core basics for the types of plastic that we most encounter, numbered according to their recycling codes. Here’s a short guide:

1) Polyethylene Terephthalate (PET or PETE)

This is one of the most commonly used plastics. It’s lightweight, strong, typically transparent and is often used in food packaging and fabrics (polyester). 

Examples: Beverage bottles, Food bottles/jars (salad dressing, peanut butter, honey, etc.) and polyester clothing or rope. 

2) High-Density Polyethylene (HDPE)

Collectively, Polyethylene is the most common plastics in the world, but it’s classified into three types: High-Density, Low-Density and Linear Low-Density. High-Density Polyethylene is strong and resistant to moisture and chemicals, which makes it ideal for cartons, containers, pipes and other building materials. 

Examples: Milk cartons, detergent bottles, cereal box liners, toys, buckets, park benches and rigid pipes.

3) Polyvinyl Chloride (PVC or Vinyl)

This hard and rigid plastic is resistant to chemicals and weathering, making it desired for building and construction applications; while the fact that it doesn’t conduct electricity makes it common for high-tech applications, such as wires and cable. It’s also widely used in medical applications because it’s impermeable to germs, is easily disinfected and provides single-use applications that reduce infections in healthcare. On the flip side, we must note that PVC is the most dangerous plastic to human health, known to leach dangerous toxins throughout its entire lifecycle (eg: lead, dioxins, vinyl chloride).  

Examples: Plumbing pipes, credit cards, human and pet toys, rain gutters, teething rings, IV fluid bags and medical tubing and oxygen masks.

4) Low-Density Polyethylene (LDPE)

A softer, clearer, and more flexible version of HDPE. It’s often used as a liner inside beverage cartons, and in corrosion-resistant work surfaces and other products. 

Examples: Plastic/cling wrap, sandwich and bread bags, bubble wrap, garbage bags, grocery bags and beverage cups.

5) Polypropylene (PP)

This is one of the most durable types of plastic. It is more heat resistant than some others, which makes it ideal for such things as food packaging and food storage that’s made to hold hot items or be heated itself. It’s flexible enough to allow for mild bending, but it retains its shape and strength for a long time.

Examples: Straws, bottle caps, prescription bottles, hot food containers, packaging tape, disposable diapers and DVD/CD boxes (remember those!).

6) Polystyrene (PS or Styrofoam)

Better known as Styrofoam, this rigid plastic is low-cost and insulates very well, which has made it a staple in the food, packaging and construction industries. Like PVC, polystyrene is considered to be a dangerous plastic. It can easily leach harmful toxins such as styrene (a neurotoxin), which can easily then be absorbed by food and thus ingested by humans.

Examples: Cups, takeout food containers, shipping and product packaging, egg cartons, cutlery and building insulation.

7) Other

Ah yes, the infamous “other” option! This category is a catch-all for other types of plastic that don’t belong in any of the other six categories or are combinations of multiple types. We include it because you might occasionally come across the #7 recycling code, so it’s important to know what it means. The most important thing here is that these plastics aren’t typically recyclable. 

Examples: Eyeglasses, baby and sports bottles, electronics, CD/DVDs, lighting fixtures and clear plastic cutlery.

There you go … the most common types of plastic that we encounter. This is obviously very basic information on a topic that one could spend months on researching. Plastic is a complex material, just as its production, distribution and consumption are. We encourage you to dive in deeper in order to understand all these complexities, such as plastic properties, recyclability, health hazards and alternatives, including the pros and cons of bioplastics. 

Below you’ll find links to some great resources that will help get you started. Enjoy!

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Tod Hardin is the Chief Operating Officer of Plastic Oceans International. He is also a filmmaker, a longtime communications professional, and has worked in a variety of industries, from casinos and entertainment, to nonprofits, broadcasting, politics, events and the fast-paced landscape of Silicon Valley’s tech world.