The Seven Deadly (Re)sins: The 7 Types of Plastic Resins Explained

Have you ever wondered what the numbers in triangular symbols on plastic products represent? In 1988, the Resin Identification Code system was established to classify the seven main types of plastic resins, a framework still used today. Each plastic type carries a numerical code from 1 to 7, revealing important information about material properties and recyclability.

Understanding the environmental implications of these seven plastics is crucial for consumers concerned about plastic pollution.

PET or PETE (Type 1) is commonly used for water and soda bottles, food containers, and synthetic fibers. It's durable and moisture-resistant, plus easily recyclable. However, recycled PET often undergoes downcycling into lower-quality products.

HDPE (Type 2) appears in milk jugs, detergent bottles, and grocery bags. It's strong and temperature-tolerant, and highly recyclable with good quality retention through the recycling process.

PVC (Type 3) is found in pipes, flooring, and medical devices. While it can be recycled up to six or seven times, it poses safety challenges during recycling due to potential chemical leaching.

LDPE (Type 4) makes plastic bags and squeezable bottles. It's inexpensive but less commonly recycled, with limited facility availability.

PP (Type 5) is used for food containers and bottle caps. Recycling is possible but difficult and not universally accepted.

PS (Type 6), used for coffee cups and packing materials, is challenging to recycle due to its low density and high volume.

Type 7 encompasses polycarbonate and mixed plastics used in eyewear and automotive parts, with recycling challenges dependent on specific composition.

While recycling is possible for all types of plastic, in practice it is really only number 1 and number 2 that are able to be reliably recycled at scale. Consumers should minimize use of difficult-to-recycle plastics and support sustainable alternatives.