Recycling Mystery: Plastic #7

Recycling plastics 1-6 is usually pretty straightforward, as each category correlates with a specific resin.

But plastic #7 is literally the “catch-all” category. Dubbed as “Other,” plastic #7 includes those resins that do not fit into categories 1-6. Many of these plastics are multi-layered resins, and common materials include plant-based and bio-based plastics made from corn, potato or sugar derivatives.

Plastic #7’s usage and properties really depend on how it is used and what is used to produce it. But what do you need to know about plastic #7 when it comes to the most important component, recycling? We debunk some common myths and get down to the mystery of the “other” plastic.

Greenware's cup is made from corn and touted as "100 percent compostable." Photo: Flickr/Shira Golding

The Juice on Bio-Based

Bio-based, or plant-derivative plastics, in theory seem like the best idea since sliced bread. Bioplastics are used to create (and replace) products typically made from natural gas or petroleum. They are biopolymers, derived from renewable biomass sources such as corn starch or vegetable oil. Polyactic acid (PLA) is one form of bioplastic, produced from glucose.

However, the debate on recycling bioplastics, specifically PLA, with mainstream PET continues to rage on, and studies on the subject seem to contradict each other.

The National Association for PET Container Resources (NAPCOR) recently voiced its concern for potential contamination of the PET recycling stream associated with PLA bottles. The trade association for the PET plastic industry in the U.S. and Canada cited its concerns involving cost of separation, increased contamination, yield loss and impact on recycled PET (RPET) quality and processing.

Bio-based plastics are often touted as “biodegradable.” But this term has several stipulations behind it. While these products may in fact have components that are capable of degrading, this process only occurs under specific conditions and biodegradable plastics cannot be composted in a backyard compost pile. Because the material requires very high heat, these plastics can only degrade in a commercial composting facility.

But is PLA better than your average PET bottle? According to Keith Christman, senior director Market Advocacy for the American Chemistry Council (ACC), it depends heavily on the product. In fact, in a study of traditional HDPE milk jugs versus glass jugs and PLA jugs, HDPE out-performed both materials.

“It depends on how that product is made and its end-of-life options,” Christman says. “It is not clear that using a bio-based material is better for the environment. There are some cases that use less plastics and resources during production, making it the better choice.”

In the end, plastics that are “compostable” may make sense in an area that has disposal options. But if commercial composting is not available, it’s better to choose a material that is accepted for recycling.

What We Know (and Don’t Know) About BPA

Bisphenol A (BPA) is typically used as an additive in plastics manufacturing, as it makes the plastic more shatter-proof. In addition to plastic bottles, BPA is used in dental fillings, household electronics and as a lining for many food cans.

As scientists and recyclers continue to study the effects of BPA, the trace amounts sometimes found in plastic #7 have become a cause for concern for some.

Most  recently, SIGG announced its reusable bottles manufactured before August 2008 utilized a liner that contained trace amounts of BPA. Considered by many as a “safer” alternative to traditional polycarbonate plastic bottles, some SIGG consumers now feel they were misled by the Swiss manufacturer when it did not openly disclose its use of BPA.

SIGG maintains that while its older bottles contained BPA, rigorous lab testing showed no leaching of the material. The verdict is still out on the actual health effects of BPA, and depending on who you ask, the effects range from harmless to serious health risks. While the reviews continue to be mixed, according to the FDA, commissioner Margaret Hamburg will soon determine how to proceed with BPA concerns.

Plastics are formed into pellets, which are then sold to manufacturing plants to create new products. Photo: Flickr/Paul L. Nettles

Recycling and Disposal Options

According to the ACC, more than 1,800 U.S. businesses handle or reclaim post-consumer plastics. Plastics recycling starts at the material recovery facility, where they are sorted either mechanically or manually from other recyclables. The resulting mixed plastics are sorted by plastic type, baled and sent to a reclaimer.

The scrap plastic is passed across a shaker screen to remove trash and dirt, then washed and ground into small flakes. A flotation tank then further separates contaminants, based on their different densities. Flakes are then dried, melted, filtered and formed into pellets, which are shipped to product manufacturing plants and made into new products.

Recycling programs for the “other” category vary greatly by location. Since it is such a broad category, many curbside programs will not accept plastic #7 at all. However, according to Christman, recycling programs are changing collection guidelines, throwing out resin codes and accepting materials based on product.

“When recyclers simply say, ‘We take all plastic bottles,’ consumers tend to recycle more because it is easier to understand,” Christman says. “Some communities now say ‘we’ll recycle this container, no matter what the resin is,’ this includes products categorized as #7.”

According to Christman, in some cases, some plastics are labeled with #7 because of requirements but can actually be recycled with other plastics, such as PET. These tricky aspects mean that double-checking what’s accepted in your local recycling program is a must-do for plastic #7.