Deciphering Plastics by the Numbers

Flip over any piece of plastic packaging, and you'll find a familiar symbol: those "chasing arrows" with a number inside.

There are seven of these resin identification codes (RICs). We know the symbol to broadly mean "recyclable," but there is more to this story.

Let's get to know them better!

Jump to a number:

1     2     3     4     5     6     7

Or, keep on reading for the full scoop!

Where Did RICs Come From

These ID numbers are now over 30 years old, first developed by the Plastics Industry Association (PLASTICS). This trade association represents the plastics industry, from processors, to machinery and equipment manufacturers, to materials suppliers and recycling entities.

Since 2008, ASTM International (American Society for Testing and Materials) has administered these resin codes. They oversee the technical standards for a wide range of materials, products, and systems.

ASTM International does not enforce compliance with its standards, but governments and corporations often rely on (or require) their standards for their operations. For example, every US toy manufacturer must meet the requirements of ASTM F963, Standard Consumer Safety Specification for Toy Safety.

What’s The Point?

Back when PLASTICS was known as the Society of the Plastics Industry, Inc., they sought to “provide a consistent national system to facilitate recycling of post-consumer plastics.” Straightforward enough.

These days, the system helps recycling facilities sort through plastic waste, separated by resin type. To preserve the value of recycled plastics, they cannot be mixed. Doing so would jeopardize the integrity of the new plastics, and possibly violate safety codes.

It’s worth noting that the presence of a RIC triangle symbol does not necessarily mean something is recyclable. Different regions process trash according to their own waste management policies.

So What Can I Recycle?

Usually, you can find which specific numbers your local municipality accepts. Then you can avoid buying plastics you know won’t be processed and recycled.

Try searching for “what numbers can I recycle in [zip code]” online.

Then look for a reliable link, like your city's .gov site or some other reputable entity.

As a rule of thumb, toss any item with a RIC symbol in the recycling, not a landfill waste bin. Trained employees at your local recycling facility will sort and process appropriately. Give your trash a chance at a second life!

You can also do your part by ensuring that your recyclables are as clean as possible before tossing. (HINT: If you would use your to-go container, utensil, or packaging a second time, it’s clean enough to recycle.)

The Triangle Design

Interestingly, the “chasing arrows” design has changed over time. On its own, without a number inside, the arrows broadly represent recycling as a concept, a nod to the the original 3 Rs.

However, the presence of a RIC symbol does not always mean a item can be recycled, however. Different regions have their own policies and capabilities, so the “chasing arrows” symbol can be misleading. As a result, the ASTM revised their symbols in 2013, swapping the arrows with a solid triangle.

This way, there would be no confusion between “this is actually recyclable” and “recycling” as a general concept. That said, this standard was not widely adopted by manufacturers. 

And yet, if you flip any given plastic product over, chances are you’ll see those “chasing arrows,” not a solid triangle.

Old habits die hard…

Deciphering The Numbers

And now, the breakdown.

Most plastics have two code options (A and B), noted below. There is no difference between them, just alternates defined by ASTM’s 2013 revision.

1 – PETE (or) 01 – PET
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Polyethylene terephthalate (now there’s a mouthful) is among the most common plastics produced. Our soft drink and water bottles, cooking oil containers, and nut butter jars are all PET. Some tote bags, carpeting, and polyester materials are also PET-based. 

Plastic dipping cup, a common take-out container (1 – PETE)

PROS	CONS
Largely recyclable (cleaned) Can have a second life (new PET bottles) Can also be shredded and spun into recycled polyester for fleece, carpets, etc.	Intended for single-use only Repeated bottle use leaches carcinogens into drinks (increasing one’s risk of developing cancer) Never fully biodegrades

Takeaway: Avoid repeat usage and always recycle PETE.

2 – HDPE (or) 02 – PE-HD
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High-density polyethylene brings durability into the plastic world. When we see trash barrels, playground equipment and benches, milk jugs, shampoo and laundry detergent bottles, thicker grocery bags, and plastic building materials...chances are, these are HDPE-based.

Plastic laundry detergent jug (2 – HDPE)

PROS	CONS
The most commonly recycled plastic and is considered one of the safest forms Relatively simple and cost-effective process to recycle Does not break down from sunlight exposure or extremes of heating/freezing	Commonplace and often perceived as “disposable” without a second thought Not positioned as recyclable, so only 30-35% IS recycled Rarely reused (voluntarily) or designed to be reusable containers

Takeaway: Eliminate plastic grocery bags & always recycle HDPE.

3 – V (or) 03 – PVC
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Polyvinyl chloride is hard to miss during any trip to a Home Depot or Lowes. The classic white piping used for sprinkler systems or household plumbing, window frames, lawn chairs, plastic fencing, garden hoses, computer cable sheathing, and certain toys are PVC-based.

Polyvinyl chloride garden sprinkler head (3 – PVC)

PROS	CONS
Revolutionized several industries, from agriculture (irrigation pipes), to healthcare (sterile tubing) Current European efforts (VinylPlus) to develop safer, sustainable PVC production methods & promote reuse	Cannot be recycled & most PVC-based products require “virgin” (first-time) plastics Known as the “poison plastic” containing toxins that can leach into our food/soil Rarely are repurposed (or even can be)

Takeaway: Avoid PVC-based plastic wrap, toys, and outdoor materials, whenever possible.

4 – LDPE (or) 04 – PE-LD
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Low-density polyethylene comes to us in the forms of shrink-wrapped food, plastic zip baggies, thinner grocery bags, produce bags, dog waste bags, bread bags, dry cleaner bags… You get the idea. Most of our thin, transparent, single-use plastic bags are LDPE-based.

Low-density polyethylene Tupperware lid (4 – LDPE)

PROS	CONS
Less toxic than other plastics (i.e. PVC), relatively safe to use Not historically recycled, but programs will recycle LDPE into things like plastic lumber and garbage can liners	Not universally recyclable through local curbside programs Not culturally positioned as recyclable or reusable, so most LDPE goes to landfills

Takeaway: Use glass storage containers, reusable silicone bags, and canvas grocery bags.

5 (or) 05 – PP
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Polypropylene commonly holds foods in non-see-through containers, like yogurt, sour cream, and margarine. Cereal box liners, plastic straws, and plasticware are commonly PP. Carpets, ropes, diapers, air filters, and COVID-19 facial masks are often PP-based.

Polypropylene Tupperware bottom (5 – PP)

PROS	CONS
Largely considered safe for reuse, depending on the original use Products like Tupperware and Gladware encourage reuse of these plastics	Only sometimes recycled (3% in the US), varying between curbside programs Releases microplastics (like most plastics) when exposed to high temperatures

Takeaway: Avoid reheating food/drink in PP products, and reuse them as long as possible.

6 (or) 06 – PS
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Polystyrene (Styrofoam is technically a brand name), commonly exists as disposable coffee cups and plates, packing peanuts, egg cartons, coolers, and to-go food “clamshell” containers. In construction, rigid foam sheets for insulation or sub-flooring can be PS-based.

Polystyrene foam to-go cup (6 – PP)

PROS	CONS
Technology for recycling PS is available today Awareness of reusing and recycling has grown	Few curbside programs accept, so PS accounts for ~35% of US landfill material Crumbles and disperses readily throughout natural environments May leach styrene (possible human carcinogen) into heated foods Certain PS chemicals have been linked with human health and reproductive system dysfunction

Takeaway: Avoid at all costs, reuse what you have, and clean it up wherever you see it.

7 – Other (or) 07 – O
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This catch-all includes any type of plastic that doesn’t fit into one of the first six categories. Number 7 products may be made from multiple plastic types or plastics that can’t easily be recycled.

This resin category also includes bioplastics, like PLA, PHA, and PHB, which can be composted if they are properly identified, sorted, and shipped to a commercial or industrial facility. It’s unfortunate that they are lumped together with “other” plastics, despite being marketed as compostable and plant-based and sustainable products.

Thankfully, some municipalities have started to accept Number 7 plastics marked with “PLA” on the bottom, denoting they are made with compostable polylactic acid.

Compostable polylactic acid drinking cup (7 – Other)

PROS	CONS
Bio-based PLA, PHA, and PHB-based No. 7 plastics can replace virtually any consumer-facing plastic usage today Both producer demand and consumer demand are rising for bioplastics Some curbside programs now accept No. 7 plastics, usually if compostable	Few curbside programs accept, so most No. 7 plastics are diverted to landfills Products made from multiple plastic types are not recyclable Polycarbonate plastics, labeled with a “PC” by the No. 7 resin code, may leach BPA (Bisphenol A), an endocrine disruptor

Takeaway: Only buy compostable No. 7 plastics and only if your municipality accepts them.

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