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Plastics Resin Codes go to: about plastics

On the bottom of many rigid plastic containers there is a code number from 1 to 7 surrounded by "chasing arrows," with an abbreviation beneath it. These resin identification codes identify different types, or resins, of plastics.

Unfortunately, the resin identification codes cause more confusion than clarity.

what the numbers mean

What the Numbers and Letters Mean




Resin Name

symbol for #1 PETE



Polyethylene Terephthalate

symbol for #2 HDPE



High Density Polyethylene

symbol for #3 V



Polyvinyl Chloride

symbol for #4 LDPE



Low Density Polyethylene,
Linear Low Density Polyethylene

symbol for #5 PP




symbol for #6 PS




symbol for #7 Other



Other Resin Types

In the system developed by the Society of the Plastics Industry (SPI), leaving NYCWasteLess plastics are divided into 7 categories. Categories #1-6 represent the most common resin types found in household waste, and #7 is a "catch all" for other resin types.

Resin refers to the basic chemical composition of each type of plastic. Each resin has unique properties and is used (often mixed with additional chemicals and materials) in the manufacture of a variety of plastic products.

Sometimes there are letters beneath the resin codes. These are abbreviations for the name of the plastic resin that the code represents. These abbreviations are not always included, though the number always represents the same resin. (See quantities of different plastics in NYC's waste.)

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Evolution of Plastics Resin Codes

The code numbers were adopted by the Society of the Plastics Industry (SPI) leaving NYCWasteLess in 1988 in response to state regulators and recyclers who wanted a consistent way to identify the different resin types of the plastic containers most commonly found in the residential waste stream.

The SPI resin identification coding system has gained widespread recognition and is used voluntarily by many manufacturers and localities worldwide. In the U.S., 39 states have adopted the system as mandatory for products sold in those places.

Public demand for environmentally responsible products has continued to grow, especially in recent years. Consequently, many manufacturers are choosing to utilize the SPI codes on a variety of plastic products in addition to the rigid containers and bottles for which they were originally intended.

You may find resin codes on plastic bags, toys, and other items that are manufactured from the resin types #1-6. In addition, the plastics covered under resin type #7 ("Other") have grown substantially since 1988, as new resins and combinations of resins are produced for specific applications.

To account for the vastly expanded universe of plastic products over the more than 20 years since creation of the original resin identification coding system, SPI announced in 2008 a partnership with the American Society for Testing and Materials (ASTM) International leaving NYCWasteLess. They will develop an update and expansion of the 1988 resin coding system to help identify all the current types of plastics.

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Problems with Resin Codes

It would be nice if the resin codes indicated which plastics can be recycled. In reality, the codes are misleading when it comes to recycling. The "chasing arrows" symbol on the codes is widely used on consumer products to indicate a recycled or recyclable item. Thus, the plastic resin codes give people the impression that a vast array of plastic products can and should be recycled in any municipal program. This is not true.

As the SPI points out in their guide to correct use of resin codes leaving NYCWasteLess: "The code was not intended to be - nor was it ever promoted as - a guarantee to consumers that a given item bearing the code will be accepted for recycling in their community."

Resin type identifies the chemical compound used to make the product, but it does not reflect all of the different manufacturing processes and additives in any plastic item. This information is needed to determine if a product can be recycled.

In particular, the numbers do not distinguish between different types of plastic molding processes, which affect whether or not a product is recyclable. Molding is the process by which hot, molten plastic is turned into a container or other rigid object in the factory. For example, Plastic bottles are blow-molded, which means that the molten plastic is shaped by blowing air into it, much as a glass bottle is blown. Plastic tubs and trays are injection molded, which means that the plastic is injected into a fixed mold to form its shape.

Blow molded and injection molded plastics have different melting points and cannot be melted together for recycling, even if they are of the same resin, and even if they share the same code! That is, a #1 bottle or jug cannot be melted with a #1 tub or tray; and a #2 bottle or jug cannot be combined with a #2 tub or tray, and so on. Each must be identified, sorted, and stored separately.

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