What is a resin identification code?
The resin identification code (what appears to be the recycling symbol with a number in the middle) appearing on your plastic bottles refers to the type of plastic used in the bottle. You will also find the code on almost every other plastic product around your home, from your grocery bags to your children’s playground equipment.
Below, we have listed each type of plastic represented by the symbols. Contrary to popular conception, the resin identification code does not mean that the plastic is made from recycled goods or is recyclable itself. While you can recycle plastic, not all plastics are recycled. This guide is meant as an encyclopedic overview of the codes, not an exhaustive resource on plastic safety. Because we discover more about the nature of plastics every year, be sure to do a little research to ensure that your plastic product is safe for use in the dishwasher, microwave, or by children.
PET – Polyethylene Terephthalate
This symbol commonly appears on soda bottles, plastic water bottles, and bottles of cooking oil. PET can also be found in polyester fibers, thermoformed sheeting and strapping. PET is recyclable; following treatment, pure “PET flakes” are used as a polyester substitute or made back into PET bottles. Because PET can leach antimony and phthalates, it is recommended that you avoid giving items made from PET to children or reusing indefinitely items made from PET.
HDPE – High-Density Polyethylene
Although you will most likely see this symbol on items from your grocer such as milk jugs, yogurt containers, and plastic grocery bags, HDPE is used in a host of other products ranging from folding chairs to playground equipment. The Ecology Center, citing a study in Food Additives and Contaminants, claims that “LDPE, HDPE, and polypropylene bottles released measurable levels of BHT, Chimassorb 81, Irganox PS 800, Irganix 1076, and Irganox 1010 into their contents of vegetable oil and ethanol,” meaning that you should exercise caution using items made from HDPE.
PVC – Polyvinyl Chloride (otherwise known as vinyl)
You may see this symbol on your bottles of ketchup and mustard in addition to Saran™ wrap, teething rings, and shower curtains, but you are more likely to see it on non-food items such as signs, ceiling tiles, and electric wires. Even though some children’s toys are made from PVC, modern research has found that PVC contains human carcinogens, which has caused states such as California to consider banning the use of PVC in consumer packaging, mainly due to the threats it poses to human and environmental health as well as its effect on the recycling stream. Speaking of recycling, while it is possible to recycle PVC, it is not done mainly because it’s more cost-effective to make new PVC rather than trying to recycle it. Also, note that plastics marked with resin identification code 3 may also contain bisphenol a (BPA), so proceed with caution when using plastics marked with 3.
LDPE – Low-Density Polyethylene
This code is generally found on the bags you use for produce in grocery stores, 6-pack holders, as well as well food storage containers. Beyond uses for food storage and conveyance, LDPE can be found in a variety of products, such as computer hardware and playground slides. Since it has resistance to moderate levels of heat and LDPE is one of the safer options for plastics.
PP – Polypropylene
There are a wide variety of uses for polypropylene, including furniture, bags, carpets, ropes, and food storage containers. In fact, because of its high melting point, companies such as Rubbermaid and Sterilite make most of their food storage products from polypropylene. Be careful, though. Recent research has found that certain chemicals may leak out of polypropylene containers at high temperatures, so be mindful of using polypropylene containers in the microwave even though most containers composed of that material are considered microwave-safe.
PS – Polystyrene (also known as Styrofoam)
Polystyrene, also known as Styrofoam, can found in all sorts of products in both its solid and “foam” incarnations, such as plastic cutlery, CD and DVD cases, packing materials, and foam drink cups. Even though polystyrene is recyclable, the low cost of virgin polystyrene generally deters people from doing so. The environmental impact of polystyrene cannot be understated. Since it takes so long to biodegrade and its decomposition creates potentially harmful by-products, managing polystyrene waste has become a hot-button topic in recent years.
O – Other plastics
This is a catch-all category for all other plastics, such as acrylic, fiberglass, nylon, and many others. Because of the wide variety of plastics in this category, you will need to do some research when using a #7 plastic to find out whether it is safe for microwave and dishwasher use or whether it is safe for children to use. Plastics marked with resin identification code 7 may also contain bisphenol a (BPA), so proceed with caution.