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August 22, 2019

7/24/2019 3:06:00 PM
What Do Those Numbers On Plastic Containers Mean?
By Cherie LeBlanc Fisher

Plastic is plastic is plastic, right?
It is that miracle substance with both strength and flexibility that we make from petrochemicals like oil, natural gas or coal and use in everything from medical equipment to food storage containers, writing tools to airplane parts.

But all plastic is not the same, of course, especially when it comes to recycling. The type or grade of plastic matters, and one can tell the difference by the numbers inside the arrowed triangles. A “1” indicates plastic made of polyethylene terephthalate, which is used to make bottles for soft drinks and cooking oil, among other things. Plastics marked “2” are made from high-density polyethylene and might be made into milk jugs or detergent bottles. “3” indicates polyvinyl chloride which contains a lot of toxins and is difficult to recycle but is made into carpet backing and white PVC pipes. Number 4 plastic is made from low-density polyethylene and is used for bread bags, clothing and furniture. “5” plastic is made from polypropylene and is used to make, for example, toys and car bumpers. “7” is a catch-all “other” category of plastics that includes nylon, fiberglass and acrylic.

That brings us to “6” plastic, which we are not supposed to put into our recycling bins in Evanston. Number 6, also known as foam or Styrofoam, is made from polystyrene. It is used to make picnic cups and restaurant take-out containers, package meats and other foods, and cushion fragile goods during shipping. Polystyrene is very lightweight but bulky which makes it expensive to handle and ship for recycling so it most often ends up in landfills where it can sit without breaking down for up to a thousand years. Polystyrene is easily contaminated by food and also contains toxins that may be released if heated or microwaved. Abt Electronics in Glenview has a special machine to “densify” polystyrene (make it more dense) for recycling, but they accept only large blocks of clean polystyrene like that used to cushion a new computer or big-screen TV (see

Besides having different chemical make-ups, each type of plastic has different properties like heat resistance, brittleness, cold tolerance and ability to withstand sunlight without breaking down. When plastic is recycled, the most efficient systems group plastics together by type (which means careful sorting in a “mixed recycling bin” system like Evanston’s). Mixing of plastics during recycling (and contamination with food or other non-plastic materials) degrades the quality and limits the reuse potential of the recycled plastic. More information is online about the different types of plastic at

And why can’t thin plastic bags be recycled? They can, just not with the regular recycling in the blue bins. This is for mechanical reasons – they get tangled in the machinery that sorts our recycling into different materials. Thin plastic bags and other plastic “film” like the packaging around paper towels and dry cleaner bags can be recycled at Jewel and Target stores and many other places. It is collected in special drop-off bins and eventually goes to Trex, a company that makes plastic decking and benches ( Go to and type in a zip code to find places that accept thin plastic bags and plastic film for recycling.

The Solid Waste Agency of Northern Cook County website (https://www. can tell you everything you ever wanted to know about recycling in Evanston and other North Shore communities.

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