Plastics Recycling Numbers on the Bottoms of Containers Are Resin ID Codes; What They Mean and How to Use Them for Safety and Recycling

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The common assumption about plastics is that those that can be recycled are categorized by embossing on the bottom with the “recycling triangle” of chasing arrows with a number from 1 thru 7 (used for resin-type identification) within the triangle. The numbers inform both the consumer and the recycler about the process that is to be used on that specific plastic to reformulate it into raw material for recycled products, but having such a symbol and number does not guarantee an item can be recycled.

Only certain plastics are readily recycled and some are not even safe for routine use. Contrary to environmental advertising designed to encourage recycling compliance from the public, there is little to no market for some recyclable plastics. Municipal recycling stations may accept all or only some of the plastics consumers may wish to recycle.

Since January 1995, 39 states have adopted legislation for using resin ID codes on bottles of 16 ounces or more and rigid containers of 8 ounces or more: Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Nebraska, Nevada, New Jersey, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Virginia, Washington and Wisconsin (Wisconsin requires use of the code on bottles of 8 ounces or more).

Recycling by Number

On the bottom of all recyclable plastic products is the “recycling triangle” with a number inside it that designates its recycling category. This misleading symbol was a plastics industry marketing ploy designed to make consumers falsely think all plastics were readily recyclable. The numbers inside follow a code designed by The Society of the Plastics Industry (SPI) in 1988 to provide a consistent national plastics recycling system and differentiate plastics types by resin content. The SPI manufacturer guidelines mandate that the resin ID codes on containers:

  • be molded, formed, or imprinted on any container large enough to accept the 1/2″ minimum-size symbol and on any container size from eight-ounces to five gallons.
  • appear on the bottom of the container, as close to the center as practicable. The similar location placement on all containers allows it to be easily located and identified.

Interestingly, SPI also ‘strongly encourages’ manufacturers to ‘adhere diligently to the following guidelines’ (SPI web site, About Plastics section, SPI Resin Identification Code – Guide To Correct Use):

  • Make the code inconspicuous at the point of purchase so it does not influence the consumer’s buying decision.
  • Do not make recycling claims in close proximity to the code, even if such claims are properly qualified.
  • Do not use the term “recyclable” in proximity to the code.

There are hundreds of consumer plastics, but the majority of plastic items are made from one of six resins: polyethylene terephthalate (PET or PETE); high density polyethylene (HDPE); polyvinyl chloride (PVC or vinyl); low density polyethylene (LDPE); polypropylene (PP); or polystyrene (PS). The SPI resin identification code assigns each of these resins a number from 1 to 6.

Other organizations besides SPI have also developed coding systems, including the Society of Automotive Engineers (SAE), the American Society for Testing and Materials (ASTM) and the International Organization for Standardization (ISO). In 2008, SPI and ASTM International began working with industry and government experts to expand the standard with additional codes for new resin types beyond those covered in codes 1-6.  Code 7 is all-inclusive of the hundreds of other resins other than those indicated by 1-6, and any combinations of them.

A List of Current Resin-ID Codes

#1 PET (or PETE) is used for soda, water, and some beer and liquor bottles, boil-in-bags, containers for mouthwash, medicine, drugs, peanut butter, salad dressing, vegetable oils, oven-safe food trays, and a variety of other consumer product and one-use beverage containers. The easiest plastic to sell back to specialty manufacturers, PET can become fiberfill for coats, sleeping bags, mattress pads, or life jackets, used to make bean bags, rope, car bumpers, tennis ball felt, combs, carpets, cassette tapes, boat sails, shopping bags, T-shirt fabric, or furniture covering, none of which can again be recycled once processed by a recycling facility.

#2 – HDPE (high-density polyethylene) is the opaque plastic used for milk jugs; juice bottles, bottles for bleach, detergent, household cleaners, shampoo, some trash and shopping bags, motor oil bottles, small tubs for butter and yogurt, and cereal box liners. A more stable plastic than PET, it is thought to be safe from carcinogens or hormone-disrupting chemicals. Used for the heavier jug-type containers for laundry detergent, cat litter, and bleach, it is also made into toys, piping, plastic lumber, and rope. Recycled HDPE is in fairly strong demand by manufacturers.  Clear HDPE can be reused for new containers, but the colored is generally recycled for plastic lumber. Indestructible Tyvek mailing envelopes and white contamination suits are made from a form of HDPE, but are impossible to recycle.

#3 – PVC (polyvinyl chloride), where the environmental pollutant dioxin is released during manufacture, is the least recyclable plastic, commonly used in plumbing pipes, shower curtains, window cleaner and detergent bottles, wire jacketing, siding, windows, vinyl dashboards, outdoor furniture, jungle gyms, and bird feeders, but collecting it for recycling is not cost-effective because too few second-life products require it.  It is also used in clear food packaging, cooking oil bottles, some baby bottle nipples, and some medical equipment like IV catheters, bags, and tubing, where the Surgeon General seems to feel that the potential exposures are low and may be outweighed by the longer storage capacity for blood and medicines.

PVC items are generally one-use and become trash when discarded, however caution indicates consumers should beware as it also releases toxins into the air as it ages and produces potentially fatal fumes if burned in an enclosed area like a house fire. It also needs additives and stabilizers to make it useable, such as lead for strength and plasticizers/softeners for flex-ibility. These toxic additives contribute to further pollution and human exposure as it breaks down.

PVC contains both estrogen-similar Bisphenol A (BPA) and phthalates, as well as DEHA (di(2-ethylhexyl)adipate), a plasticizer which households are exposed to daily through food, water, air, and many consumer products. DEHA is linked to liver cancer, adverse effects on kidneys, spleen, bone formation, and body weight. PVC cling wrap has DEHA that leaches into oily foods on contact, increasing leaching when heated. Whether recycled or discarded, it is a very dangerous product that can one day come back to haunt us.

#4 – LDPE (low-density polyethylene)is flexible and is used for wrapping films, dry cleaning bags, tote bags and bags for sandwiches, grocery items, bread, and frozen food, as well as condiment squeeze bottles, clothing, furniture, and carpet. The bags may be recycled into new bags or plastic lumber such as Trex, but the transportation and recycling process has been found to use more energy than producing a virgin product. So, while is it recyclable, most LDPE ends up as trash in a landfill. For a long time it had to be thrown away, and is just beginning to be accepted through curbside recycling programs. Recycling centers like EDCO take it and many grocery stores accept plastic grocery bags back.

#5 – PP (polypropylene), which does not contain Bisphenol A, is used in yogurt and margarine tubs, condiment and syrup squeeze bottles, bottle caps, drinking straws, medicine bottles, and other food containers including Tupperware and new BPA-free baby bottles.

Few municipal recycling centers accept PP due to its very low rate of recyclability and it hasn’t enough second-life uses to justify its collection and transportation for recycling. It is a hard plastic than can accept a lot of heat, so it is often used for food containers. In locations where large companies or industries use PP, there can be enough volume for recycling it to be cost effective. Most curbside recyclers don’t yet accept it, but some recycling centers may take it in a mixed or miscellaneous bins.

#6 – PS (polystyrene or styrofoam) in solid form (solid PS) is made into compact disc jackets, eating utensils, and take-out food containers, as well as coffee cups, egg cartons, aspirin bottles, disposable plates, cups, cutlery and meat trays, packing peanuts, and insulation. Unless kept cold, PS readily leaches toxins into foods. Leaching at room temperature is moderate, but in heat, leaching increases. If you leave a takeout container of food in a hot car for a few hours, when you find it, throw it away!

PS is widely accepted because it can be reprocessed into many items including cassette tapes and rigid foam insulation. The cost of transporting used styrofoam products is greater than making it from virgin oil. There is no way to recycle it and even EDCO will not take it. It gets buried in landfills, dots public landscapes like a blight, and may appear as food to animals and birds who ingest it, incidentally or accidentally, with no warning that it will cause undue suffering and usually kill them. It can be seen on playgrounds and sidewalks, as well as on mountain trails, in dense woods, floating down streams and rivers, and far out at sea. For the environment, the animals, and yourself, buy something else. Bring a ceramic cup to work.

#7 – Other is the category that contains some relatively safe plastics, but is also designated for items crafted from polycarbonate (a hormone disruptor), combinations of plastics, or unique or uncommon plastic formulations. These are the hardest plastics to recycle. Usually imprinted with the catch-all designation #7 (or having no number), these plastics are seldom collected. Presently, recycling them is virtually impossible, along with most bottle caps and container lids. Few consumers will return items to the product manufacturers to avoid contributing to landfills and they become trash. Check for this number or items having no number before buying and avoid these plastics.

What Is Safe and What Is Not

A comment must be offered about SIGG and Gaiam, considered giants in the manufacture of green products, specifically re-usable metal bottles. Choices include both aluminum and stainless steel, but aluminum bottles require an interior plastic liner to prevent the aluminum from leaching into the water. Consumers wishing to bypass the environmental effects of disposable plastic bottles, as well as avoid the estrogen-mimic BPA, and avoid stainless steel bottles made in China, often choose aluminum water bottles with BPA-free liners. It is the BPA content of this liner that Sigg and Gaiam have lied to consumers about for years.

SIGG’s aluminum water bottles have now been proven to contain BPA. Gaiam’s aluminum water bottles, sold with a “BPA Free” label, have also been proven to contain BPA, and to leach it into the contents at 20 times the levels of SIGG bottles. Once independent testing on this was made public, Gaiam posted the test results on its web site showing BPA leaching at 23.8 parts per billion. This is greater than 10 times the detection limit that SIGG provided in its own water bottle testing, and more than 18 times greater than leaching levels found in independent studies of SIGG water bottles.

The rule of thumb for basic safety for petroleum-based plastics is that the safer plastic recyclables sport the numbers 1, 2, 4, 5. Anything labeled with 3, 6, 7, or any other number is not safe and should be avoided or discarded, specifically any baby food containers or bottles, sippy cups, or baby items.  Use only ceramic or glass containers in microwaves, and never microwave any plastics.

According to the Smart Plastics Guide put out by the Institute for Agriculture and Trade Policy, bottled water bottles labeled with 1 or 2 should be considered one-use bottles. Bio-based plastic water bottles from plant-based plastic substitutes are now available and are much safer.

Bio-based plastics are the newest green industry, providing biodegradable products recyclable in municipal composting facilities.They hold great potential to replace petroleum-based plastic products and are now used for many food and beverage containers. Natureworks manufactures polylactic acid, or PLA, a corn-based plastic used in containers, bottles, and cutlery. EarthShell makes a foam laminate from potatoes, corn, rice or tapioca for food wraps, eating utensils, and takeout containers.


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