Dear EarthTalk: Everyone knows we should recycle metal, glass and plastic cans and bottles, but what about all the lids, tops and caps? I see people recycling plastic bottles, for example, with their caps on, but I've always been told to thrown them out. Is that wrong?

-- Stefanie Gandolfi, Oakland, CA

Many municipal recycling programs throughout the U.S. still do not accept plastic lids, tops and caps even though they take the containers that accompany them. The reason is that they are not typically made of the same kinds of plastics as their containers and therefore should not be mixed together with them.

“Just about any plastic can be recycled,” says Signe Gilson, Waste Diversion Manager for Seattle-based CleanScapes, one of the west coast’s leading “green” solid waste and recycling collectors, “but when two types are mixed, one contaminates the other, reducing the value of the material or requiring resources to separate them before processing.”

Also, plastic caps and lids can jam processing equipment at recycling facilities, and the plastic containers with tops still on them may not compact properly during the recycling process. They can also present a safety risk for recycling workers. “Most plastic bottles are baled for transport and if they don’t crack when baled, the ones with tightly fastened lids can explode when the temperature increases,” says Gilson.

Some recycling programs do accept plastic caps and lids, but usually only if they are off their containers completely and batched separately. Given the many potential issues, however, most recyclers would rather avoid taking them altogether. Thus it is hard to believe but true: In most locales the responsible consumers are the ones who throw their plastic caps and lids into the trash instead of the recycling bin.

As for metal caps and lids, they, too, can jam processing machines, but many municipalities accept them for recycling anyway because they do not cause any batch contamination issues. To deal with the potentially sharp lid of any can you are recycling (such as a tuna, soup or pet food can), carefully sink it down into the can, rinse it all clean, and put it in your recycling bin.

Of course, the best way to reduce all kinds of container and cap recycling is to buy in large rather than single-serving containers. Does the event you’re holding really require dozens and dozens of 8- to 16-ounce soda and water bottles, many of which will get left behind only partly consumed anyway? Why not buy large soda bottles, provide pitchers of (tap) water and let people pour into re-usable cups?

The same kind of approach can be taken with many if not all of the bottled and canned grocery items we buy routinely for the home. If more people bought in bulk, apportioning out of larger, fewer containers, we could take a huge bite out of what goes into the waste stream.

CONTACT: CleanScapes, www.cleanscapes.com.

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