Plastic usage has grown tremendously in the last 50 years. The U.S. Environmental Protection Agency estimates production increased from 390,000 tons in 1960 to more than 30 million tons in 2007. However, unlike paper and yard trimmings, plastics have a relatively low rate of recovery -- less than 7 percent. Of the types of plastic available, those rated with the resin codes 1-PET and 2-HDPE have the best recovery rate: 36.6 and 28.0 percent, respectively. (See Reference 1, pages 7, 35 and 51.)
Plastics typically contain petrochemicals, or chemicals derived from petroleum. They can be organic or inorganic, depending upon the chemicals and end use. Other additives help the usability of a plastic for a particular function. Plastics have a range of uses, from flexible packaging to lumber to polyvinyl chloride piping. This wide assortment of chemical structures precipitated the need for a uniform rating system for recycling plastics. The rating denotes the type of plastic and can be used as a guide to determine whether an item can be recycled. (See References 2 and 3.)
The Society of the Plastics Industry developed the resin identification code system in 1988. It summarizes the type of resin, chemical properties, applications and products made with recycled materials for seven types of plastics. Not all plastics are recyclable. Some plastics require more sophisticated processing techniques to recover the material; for others, frequent recycling may deteriorate their chemical structure. Curbside recycling centers may place restrictions on which plastics they accept, based on market demand and the difficulty of the recycling process. (See References 2 to 4.)
You are most likely to encounter plastics with the resin codes 1-PET or 2-HDPE. The polyethylene terephthalate resin is used for beverage and food containers and for microwavable trays. Recovered 1-PET plastics become fiber for carpets and fiberfill. Heavier containers like milk jugs or those for household cleaners are made with high-density polyethylene plastics with the resin code 2-HDPE. Its stronger and stiffer structure makes it better suited for these uses. These recycled plastics become plastic lumber and nonfood containers. (See Reference 2.) Most recycling facilities accept PET and HDPE plastics.
Plastics with higher resin codes serve other functions that require greater strength or chemical resistance. These products may fill specific niches. For example, blister packs for products such as pharmaceuticals contain 3-PVC plastics. Resin code 3 also denotes vinyl or composite vinyl products. PVC is expensive and difficult to recycle, so it is typically only accepted at specialty facilities. Container lids and toys often contain low-density polyethylene plastics that are flexible and resistant to acids and vegetable oils. Larger 4-LDPE items and plastic wraps are often accepted, though container lids are often too small to recycle. Recycled goods from resin codes 5-PP, 6-PS and 7-OTHER are made of durable polypropylene, polystyrene and other plastics, respectively, and are typically only recovered through specialty facilities. Resin code 7 is a catchall for many materials, like acrylic, fiberglass and composite plastics. (See Reference 2.)
- U.S. Environmental Protection Agency: Municipal Solid Waste in the United States: 2007 Facts and Figures
- U.S. Environmental Protection Agency: Common Wastes & Materials - Plastics
- Iowa Department of Natural Resources: Economic Impacts of Recycling in Iowa
- Town of Concord, Massachusetts: Why Some Things Can't Be Recycled at the Curb?
- Brand X Pictures/Brand X Pictures/Getty Images