Recycling by numbers

When sorting plastic recyclables, you’ve probably noticed the number inside of those funny arrows that form a triangle. And you’ve likely surmised that the arrows form the symbol for recycling. What you probably don’t know is what the numbers mean or where they come from.

Well, it turns out the numbers are a code that allows recyclers to easily identify various types of plastics. The Society of the Plastics Industry and the Federal Trade Commission established the guidelines. Here are the types of polymers as they correlate to the numbers, and some of the products they comprise:

1 Poly(ethylene terephthalate): Soda bottles, water bottles, vinegar bottles, medicine containers.

2 High-density polyethylene: Containers for laundry detergent, fabric softener, bleach, milk, shampoo, conditioner, motor oil.

3 Poly(vinyl cloride): Pipes, shower curtains, meat wraps, cooking oil bottles, baby bottle nipples, shrink wrap, coffee containers.

4 Low-density polyethylene: Grocery and sandwich bags.

5 Polypropylene: Syrup bottles, yogurt tubs, diapers, outdoor carpet.

6 Polystyrene: Coffee cups, disposable utensils and cups, Styrofoam insulation.

7 Other: Any combination of plastics 1-6; these are less common than the others.

Source: Polymer Science Learning Center