Plastics Part 5: Low-Density Polyethylene is Low on the Recycling List

Guest blogger, Jessica Connolly of Recology San Mateo County explores plastics and her relationship to them in this series.


The bag, not the shoes! Src: R. Steven Rainwater via flickr.com

            Low-Density Polyethylene (LDPE) is another plastic we use in our everyday lives.  The polyethylene-based plastic is in the same family as HDPE. Unlike HDPE, however, LDPE is usually a soft or film plastic with many types of softeners added to make it stretchy, pliable and flexible.

                The most common use for LPDE is the disposable plastic bag. In 2008, 1.2 trillion plastic bags were used around the world. They are used in grocery and clothing stores, wrapped over dry-cleaning, used in Ziplock bags, and hold your produce bags. LDPE is also the most common plastic used in packaging; almost anything that comes covered in soft plastic is LDPE. LDPE is also sometimes used in cling wrap to cover many types of food products. Lids on reusable plastic food containers may also be made with LDPE because the resin’s characteristics enable it to snap on tightly and prevent leakage.

                LDPE is another plastic of concern for several reasons. Many of the softeners added to the plastic to create flexibility, pliability and elasticity contain chemicals leach out into our food products and infiltrate our bodies.

                Many LDPE products, especially plastic bags, end up as litter. They get caught in trees, tumble along roadways, and sink in our oceans. Because of their properties, LDPE easily breaks apart into smaller and smaller confetti-like pieces, covering earth, plants, rocks and other elements of the environment with this plastic pollution, damaging ecosystems and endangering wildlife.

                LDPE is particularly difficult to recycle because of the damage it causes to machinery in municipal recycling programs; this soft plastic gets caught in the wheels and gears and can break the machines that are running to sort bottles, cans and paper. However, many grocery stores collect clean, dry plastic bags made of LDPE and send them to recyclers who turn them into new film plastic or infrastructure like plastic lumber, parking bumpers and road signs.

5 Responses to “Plastics Part 5: Low-Density Polyethylene is Low on the Recycling List

  • Leraning a ton from these neat articles.

  • God, I feel like I souhld be takin notes! Great work

  • SF Resident
    6 years ago

    What about LDPE foam (#4 packing foam) which is now used by some for protecting fragile items in packaging? It’s not completely hard like HDPE but it’s also not like a plastic bag. Can we recycle it in San Francisco?

    • Recology does not currently take packing peanuts in our recycling program, but there are other recycling and reuse options. Visit recyclewhere.org for more information.

      • SF Resident
        6 years ago

        Erin – thank you for your response. Can you clarify whether you answer applies only to packing peanuts, which are usually styrofoam (#6), or all packing material including LDPE foam, which is #4 plastic, not #6.

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