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Stolen: Deciphering plastics

by Joanne Stolen

One of my pet peeves is the labels on plastic – that little triangle with a number inside it that the plastic manufacturers are required to place on bottles and containers. Most of the time I can’t read the number, it is so small or indistinguishable. I have even taken to rub a pencil across the number to get some contrast so I can decipher it. In Summit County we can recycle Nos. 1 and 2. Why are some yogurt containers like Dannon Active #2 recyclable and most others are #5? What can’t they make them all out of #2? I’ve decided to look into what these symbols mean.

It turns out these labels have nothing to do with the recyclable nature of the plastic. It is an international standard to identify what plastic is used by the Society of the Plastics Industry, Inc. to provide a uniform system for the identification of different polymer types. The plastics are divided into seven distinct types. Number 1 is polyethylene terephthalate or PETE. Soda bottles, cooking oil, peanut butter, water bottles are made out of this type of plastic, and this plastic is recyclable. There are some claims that this plastic releases a chemical which may be carcinogenic. No. 2 is high-density polyethylene or HDPE. Common uses are detergent bottles, milk jugs, oil bottles and, yes, Dannon Active yogurt. No. 3 is polyvinyl chloride (PVC), which is used to make plastic pipes, plastic furniture, shrink wrap, blister packaging and plastic bags. There are reports that soft PVC often contains and can leach toxic phthalates, and can also give off chemicals into the air. No. 4 is low-density polyethylene (LDPE) and some bags, trash can liners and food storage containers are made out of this type. No. 3 and No. 4 bags are accepted for recycling at a lot of the food stores.

No. 5 is polypropylene (PP), which is in bottle tops, drinking straws, yogurt and margarine containers. No. 6 is polystyrene (PS): packaging pellets, cups, plastic tableware, and meat trays. It has been found to leach styrene – a neurotoxin and possible human carcinogen – and has been banned in cities like Portland, Ore. and San Francisco. No. 7 is “other” and can be any of several different plastic polymers. This type is used to make plastic containers. This type is used in Nalgene’s reusable water bottles and has been found to leach bisphenol A, a hormone disruptor that mimics estrogen.

What happens to the bottles we recycle? The bottles are sorted by color and their Plastic Identification Code, and then the bottles are squashed into big bales. These bales of plastic bottles are bought by reclamation facilities, which wash and grind the plastic into smaller pieces. These small pieces of plastic are dried and then go through a melt filtration process creating resin pellets which are ready for the remanufacturing into new plastic material. Sometimes these are reprocessed into products completely different in form from their original state. Soft drink bottles can be cast into plastic chairs and tables.

There are also bioplastics (made from plant-based material rather than the usual petroleum base for plastic). Most common of these is PLA, or polyactide, which is most commonly made with corn. It can be composted in industrial composting operations. The use of biodegradable plastics is increasing. There are various new processes being developed for recycling plastics. One which is gaining ground is a heat compression process which takes all unsorted, cleaned plastic in all forms, from soft plastic bags to hard industrial waste, and mixes the load in large rotating drums.

Low national plastic recycling rates in the U.S. are due to the complexity of sorting and processing, unfavorable economics and consumer confusion about which plastics can actually be recycled. Most often we can’t read them, my big pet peeve. We need to recycle as much as we can, and use cloth bags for our groceries. Those plastics that are not recycled remain in the environment and were a topic of a previous article. For more information about recycling in Summmit County, go to http://www.highcountryconservation.org.

Breckenridge resident Dr. Joanne Stolen is a former professor of microbiology from Rutgers now teaching classes at CMC. Her scientific interests are in emerging infectious diseases and environmental pollution.


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