Understanding Plastic Recycling Numbers

Are you confused by the numbers on the bottom of plastic containers? Do you think that the triangle on the bottom of a container means it is recyclable regardless of the number inside of it? Do not feel badly. I once thought the same thing. However, only numbers one and two are accepted as recyclable by the majority of garbage companies. As a writer for Earth911.org states, “PET and HDPE are the most common forms of plastic, so they are the easiest to find recycling locations for.”

The resin identification coding system was introduced in 1988 by the Society of the Plastics Industry, Inc. According to the website AmericanChemistry.com, the system was created to “meet recyclers' needs while providing manufacturers a consistent, uniform system that could apply nationwide.”

What does each number mean? As Julie Andrews sings in a movie, “Let’s start at the very beginning.” Number 1 has the letters PET next to it and stands for polyethylene terephthalate. PET is a type of polyester material that “came into prominence in the 1950s as a textile material”“Manufacturers want recycled PET and buy it.” because its “strength, temperature tolerance and wear-resistance made it an ideal replacement for, or addition to natural fibers such as silk, cotton and wool."

Number 2 (HDPE) stands for high-density polyethylene, and is used for “bottles, cutting boards, dipping baskets, dippers, trays, and containers.” Most recyclable companies accept HDPE. It is the “high density version of PE plastic.”

Number 3 (PVC) stands for polyvinyl chloride, which is found in a wide variety of products, including packaging, credit cards, and pipes. It is also used in window frames, flooring, and wallpaper. According to Greenpeace, “the production of PVC creates and releases one of the most toxic chemicals – dioxin,” and can “leak harmful additives during use and disposal.” It is difficult to recycle, so most PVC products wind up in landfills. As one website states, “PVC pipe is everywhere.”

Number 4 stands for (LDPE) low-density polyethylene; “a type of polyethylene (plastic) that is used for moulding, film, pipe conduit, wire and cable.” It is recyclable but “many places do not accept it due to the fact that it cost too much to transport because it is so light.”

Number 5 stands for (PP) polypropylene, which is a “PP is a by-product of oil refining processes.” Although it is possible to recycle PP, very little does in fact end up in recycling plants. The reason is that it is difficult for recycling plants to separate it from other plastic products, and “in many places it is only economically viable to recycle a few select types.”

Number 6 (PS) stands for polystyrene, which is used to make foam products. PS is made from styrene which is “known to indiscriminately attack tissue and the nervous system” and is absorbed through the skin, lungs and intestines. Although possible to recycle PS, most cities do not recycle PS products. It takes about 900 years for PS products to break down in landfills.

Number 7 stands for other. The American Chemistry Council describes it as indicating “that a package is made with a resin other than the six listed above, or is made of more than one resin and is used in a multi-layer combination.”


Anonymous said...

Hey, there:

I wrote a post similar to this a couple of months ago, when someone asked me how she could recycle prescription bottles. You can read it here:




Gina-Marie Cheeseman said...

Thanks, Leah!

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