A Straight Dope Classic from Cecil's Storehouse of Human Knowledge

What does the "chasing arrows" recycling code on plastic products mean?

August 18, 1995

Dear Cecil:

On the bottom of most plastic containers I've noticed a triangle-shaped symbol indicating that the container is recyclable. In the middle of this symbol is a number ranging from 1 to 6 or higher. I know these numbers have something to do with the classification of plastic products, but what is the difference between a 1 and 2 or 6 in terms of recycling? Finally, why do most recycling centers take type 1 or 2 containers but not 3 through 6? Where are we supposed to take these other products so they can be recycled? I want to recycle but it is hard to do with all this confusion.

Cecil replies:

Things are more confused than you realize. The main problem is that the triangle symbol, more commonly known as the "chasing arrows" symbol, doesn't indicate recyclability, contrary to wide belief. The number just indicates the type of plastic. As I've written before, the numbers range from 1 to 7, 1 through 6 being the most commonly used plastic resins while 7 is miscellaneous. It's important to keep the types separate when recycling because they have different melting points and other characteristics and if you throw them all into the pot together you wind up with unusable glop.

Although it's technically possible to recycle most plastics, recycling types 3 through 7 is rare because using virgin material is cheaper. Things are better with type 1 (polyethylene terephthalate or PET, used for pop bottles) and type 2 (high-density polyethylene or HDPE, used for milk and detergent bottles). Twenty-seven percent of type 1 is recycled, including 41 percent of plastic pop bottles, because type 1 containers usually are easy to sort and clean, the stuff can be used to make a lot of products, and virgin type 1 feedstock is relatively expensive. Type 2 is less attractive (for one thing, it's hard to get rid of the smell from old milk bottles); still, the bottles are big and easy to sort out of the waste stream. About 7 percent of type 2 plastic is recycled.

Types 3 through 7 you might as well throw away. Recycling rates for these materials range around 1-2 percent. Some recycling operations won't even take types 1 and 2, arguing that plastic items of whatever type are so bulky in proportion to their value that it's a waste of fuel to send out a truck to haul them away. The recycling rate for all plastic packaging is a dismal 4.5 percent, compared with 53 percent for aluminum.

Some environmentalists think it's deceptive to use the chasing-arrows recycling symbol on plastic packaging since it fools people like you into thinking the product is likely to be recycled when the overwhelming probability is that, except for bottles, it won't be. In 1993 and '94 representatives of the National Recycling Coalition and the Society of the Plastics Industry attempted to work out an improved symbol that would address this objection. The effort foundered on — get this — the new symbol's shape. The final proposal called for replacing the chasing arrows with an ordinary triangle and adding a letter to the numbers (e.g., 2B) to help sort different grades of plastic within each type. SPI's board approved the plan but NRC's refused, saying the triangle and the recycling symbol looked too much alike and suggesting a square or rectangle instead. SPI said no way. It claimed a rectangle would increase industry retooling costs 400 percent. A triangle would let plastics companies modify existing molds, changing the chasing arrows into a triangle with an engraving tool, whereas a rectangle would mean making completely new molds at great expense. In the absence of an agreement, the old system will remain in place indefinitely, since 39 states now require it and only a united front on the part of recyclers and plastics companies would persuade state legislatures to enact a change.

So what are you supposed to do? Given the difficulty of recycling plastic, a lot of environmentalists say it's best to avoid disposable plastic altogether when possible. Of the plastic you do buy, most local recyclers will take types 1 and 2; make sure you rinse all items carefully first. Above all, don't mix in types 3 through 7 (unless your recycler specifically says they're OK), plastic without a code, or random garbage. Some poor stiff will have to slog through the junk sorting it later if you do.

Old plastic in new bottles

Dear Cecil:

In response to your recent opus on plastics recycling, I thought you might want to update the Teeming Millions regarding the enclosed.

Cecil replies:

The enclosed article, which is incorrectly headlined, "Mixing Plastics Is Now OK," describes a new plastics recycling process developed by Northwestern's Basic Industry Research Laboratory. (Actually, the basic process was developed in Germany to recycle tires; NU's contribution was to adapt it to plastics.) The process, known as "solid state shear extrusion," uses a "twin screw extruder" to pulverize a random collection of old plastic under high pressure. Unlike conventional grinding methods, this causes the plastic not simply to mush together but to recombine in ways not yet fully understood. The result to some extent is new plastic that I'm told can be used to make "high value products." The high value product shown at a demonstration a few months ago was a souvenir key chain, but I guess everything's relative. The new process promises to be everything current plastics recycling methods aren't: cheap and hassle-free, since any mixture of old plastic can be used as feedstock.

The key word above is "promises." The new process was only recently introduced and has not yet proven itself in the marketplace. Several companies have expressed interest but commercial application is still at least 18 months to two years away. Until your local recycler specifically tells you otherwise, do not, repeat do not, mix different types of plastic. Not that I have any doubts whatsoever about the viability of this thing, but in 1959 the magazines said we'd soon all be living in underwater cities and I'm still waiting for those, too

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