What the Numbers on Plastic Mean
Plastic that ends up in a landfill will sit for hundreds of years leaching toxins into the soil and groundwater. Most consumers do not know or understand the true meaning behind the numbers on plastic. This number tells you both the type of plastic used and which type is recyclable or even reusable. Many plastic-based products cannot break down and cannot be recycled.
Recyclable plastic usually comes with a little recycling symbol printed on the bottom and depending on the product, there might be a 1, 2, 3, 4, 5, 6, 7, ABS (9), or PA stamped in the center of the symbol. The number is a resin identification code, used to help recycling plants sort materials.
What You Need To Know About Numbers on Plastic Packaging
Recyclable plastics are labeled with numbers 1-7 or acronym letters ABS, PA to tell workers what kind of plastic it is, and how it should be processed. But it also helps recycling collectors determine what items they can accept—and which ones go in the trash. These numbers are valuable consumer information, because they spell out the likelihood of your recycling ending up in a landfill.
Most plastic that displays a one or a two number is recyclable. But plastic that displays a three or a five often isn’t recyclable. A three indicates that the water bottle has been made from polyvinyl chloride, a five means that it’s been made of polypropylene, two materials that are not accepted by most public recycling centers.
Whenever possible, avoid plastic packaged products, including plastic water bottles. Refuse single–use plastics, Use reusable shopping bags for groceries, use a reusable water bottle or coffee mug, store foods in glass jars instead of plastic containers, avoid disposable utensils and bring reusable glass containers to restaurants in case you need to take your food to go. The most toxic plastics are #7, #3, #6, and ABS (#9).
What the Numbers Mean
Here is a list of the 7 numbers and letter acronyms, what they mean, and which ones are most hazardous to you:
Plastic Number 1
Polymer Name: polyethylene terephthalate (PET or PETE).
Found In: most plastic drinking bottles used for water, soft drinks and juices, peanut butter jars, microwavable food trays, and jelly, jam, salad dressing, and condiment containers. And thin films (bags and snack food wrappers).
Even if you don’t know the term “polyethylene terephthalate,” you’ve probably encountered this type of plastic before. It’s the most frequently recycled one. However, avoid reusing. PET is meant for single–use applications; repeated use increases the risk of bacterial growth and leaching harmful chemicals, like carcinogens. It’s also notoriously difficult to clean.
PET (or PETE) plastic does not contain bisphenol–A (BPA). While it’s considered somewhat safe, it can leach a toxic metal called antimony used during the manufacturing process. The rate of leakage increases with temperature, which is why you should never drink water from a plastic water bottle that’s been sitting in the sun all day.
Antimony can cause acute and chronic health issues like diarrhea, vomiting and stomach ulcers, according to the Agency for Toxic Substances and Disease Registry (ATSDR) at the U.S. Center for Disease Control (CDC). The content of antimony increases the longer the bottle or container sits (on a shelf, in a fridge, etc.). Other factors influencing he amount of antimony leeching from these bottles are exposure to sunlight, higher temperatures, and varying pH levels.
Plastic Number 2
Polymer Name: high–density polyethylene (HDPE).
Found In: cloudy or opaque plastic used for milk jugs, juice, shampoo, cereal–box liners, laundry detergent bottles, butter tubs, motor oil bottles, and some shopping bags. It’s a little tougher than PET, but nearly as common. It’s also fully recyclable.
HDPE is considered a low–hazard plastic, but a recent study in the science journal Environmental Health Perspectives (EHP) published in PubMed Central (PMC) by the National Center for Biotechnology Information (NCBI), U.S. National Library of Medicine (NLM), National Institutes of Health (NIH), suggests that all plastics (including HDPE) release estrogenic chemicals, which cause health problems, especially in pregnant women. They found 95% of plastic products tested positive for estrogenic activity. Meaning they can alter the structure of human cells, and pose a tremendous risk to infants and children.
Plastic Number 3
Polymer Name: polyvinyl chloride (PVC or V).
Found In: is best known for its use in pipes, but that’s not the only product that relies on plastic no. 3. PVC also appears in cooking oil, window cleaner spray and shampoo bottles, medical tubing, wire jacketing, shrink wrap, deli and meat wrap, bags for bedding, plastic toys, and table cloths.
PVC is used for a lot of plastic food wrapping because it’s soft and flexible. Most consumer recyclers will not take PVC products. Avoid reusing PVC products, especially when it comes to food or children. PVC is a highly toxic plastic. It contains the phthalate (DEHP), a toxic chemical that disrupts the endocrine systems of wildlife, causing genital deformations, low sperm counts, testicular cancer and infertility in species like deer, polar bears and whales.
These toxins leach throughout its entire life cycle. Phthalates have been linked to asthma in children, and having a negative effect on the immune system.
Plastic Number 4
Polymer Name: low–density polyethylene (LDPE).
Found In: squeezable condiment bottles and toys, but it’s mostly used in plastic films. That means shrink wrap, as well as bags—dry cleaning, grocery, bread, frozen food, and produce bags, newspapers, fresh produce plastics, garbage bags, and coatings for hot–beverage cups and milk cartons.
Though most plastic bags are not recyclable, some companies and recycling centers have found alternatives or are investigating how to recycle plastic bags given their harmfulness to the environment.
LDPE is reusable and safe to repurpose. LDPE is a low–hazard plastic, the only concern with this material is the possible leaching of estrogenic chemicals (like HDPE).
Plastic Number 5
Polymer Name: polypropylene (PP).
Found In: cloudy or opaque plastic used in Rubbermaid containers, clouded plastic baby bottles, syrup, ketchup, and medicine bottles, containers for condiments, margarine and yogurt, potato chip bags, cereal bags, and deli foods. You’ll also find it in bottle caps and straws. Has a high melting point that makes it great for containing hot liquids.
Polypropylene is recyclable though many recyclers still don’t accept it. PP is considered safe for reuse, and is another low–hazard plastic. Although one study published in PMC by NCBI, NLM, NIH found PP–made laboratory plastic–ware leached at least 2 chemicals used in the manufacturing process: the lubricating agent oleamide, and cationic biocides, used to prevent bacterial growth.
Plastic Number 6
Polymer Name: polystyrene (PS).
Found In: this versatile plastic can be manipulated into a soft foam, like packing peanuts, or hardened into a sturdy CD case. PS is further used in take–out containers, disposable Styrofoam drinking cups, bowls, plates, cutlery, and meat trays, aspirin bottles, and egg cartons.
PS is not recyclable and accounts for about 35% of US landfill material. Because it breaks apart so easily, it’s found ingested by marine animals and littering beaches. Avoid using and especially reusing polystyrene at all costs, because chemicals present in polystyrene have been linked to human health and reproductive system dysfunction.
This plastic has the ability to damage your nervous system by leaching styrene, a known human carcinogen, into foods especially when heated in a microwave. The level of styrene that leaches into food appears to be temperature–dependent, so never use disposable cups and take–out containers for hot beverages or hot food—instead, opt for a reusable cup and bring glassware when eating out, to take your leftovers home.
Plastic Number 7
Polymer Name: plastics like acrylic, nylon, polycarbonate and polylactic acid (OTHER or O).
Found In: 3– and 5–gallon refillable water jugs, citrus juice bottles, ketchup bottles, oven–baking bags, and custom packaging.
There’s no long or fancy name for this plastic, because plastic no. 7 is more of a miscellaneous category for everything that doesn’t fit into the first six categories. Because this is such a nebulous group, local municipalities are unlikely to collect these plastics.
One of the worst plastic types, nothing with the #7 can be recycled or reused. These plastics almost always contain the hormone–disrupting chemicals bisphenol–A or –S (BPA or BPS). These endocrine disruptors (xenoestrogens) mimic or interfere with your body’s hormones and can cause issues in humans, children, and fetuses. In the case of a pregnant women, they can cause spontaneous miscarriages, chromosomal errors in the fetus, and genetic damage. In the case of adults and children, they can lead to precocious (early) puberty, disrupted reproductive cycles, reduction in sperm quality, ovarian dysfunction, cancer, and heart disease.
Just one week of using plastics labeled “7” can increase urinary BPA concentrations by up to two–thirds. This plastic type has also been linked to obesity and insulin resistance, and may be present in over 95% of adults.
Acrylonitrile Butadiene Styrene (ABS) Plastic
Polymer Name: acrylonitrile butadiene styrene (ABS, or #9).
Found In: across multiple industries to produce LEGO bricks (and other plastic toys), computer keyboards, power tool and computer housings, wall socket guards. It is a common material for manufacturing different automobile parts Corrugated plastic sheets and tubing made from ABS material are used in construction and for manufacturing hard hats and helmets. In common home and kitchen appliances like vacuum cleaners, food processors, shavers, refrigerator liners, appliance control panels, toasters, irons, and electronic equipment. Injection molding and extrusion molding (3D printing, CNC machining) are the two most common uses for ABS plastic.
ABS plastic is a thermoplastic polymer that is created when acrylonitrile and polystyrene monomers are polymerized with butadiene rubber. This blending is accomplished using an emulsification process. There are also patented processes such as continuous mass polymerization.
- Acrylonitrile: this synthetic monomer is created by bonding propylene and ammonia together.
- Butadiene: this synthetic rubber monomer is a hydrocarbon rubber created by taking petroleum–based compounds and knocking off their hydrogens to create unsaturated hydrocarbon chains.
- Styrene: the styrene monomer is created by a similar “dehydrogenation” process as butadiene. ABS plastic is typically composed of ~50% styrene with the other two monomers in variable quantity.
ABS Plastic Toxicity
ABS plastic is a petroleum–based plastic that is considered generally safe in its solid form. But ABS gives off significant fumes and smoke when heated, both of which are pollutants and a health concern. A 2019 study investigating the cell toxicity of acrylonitrile butadiene styrene fumes generated from 3D printing found that ABS emissions induced a dose–dependent significant cytotoxicity, oxidative stress, apoptosis, necrosis, and production of pro–inflammatory cytokines and chemokines.
Medical device manufacturers also prohibit the use of ABS in medical implants, as its long–term health effects within the body are unknown but thought to be negative. It is also not advisable to use ABS in high heat scenarios because of its low melting point.
When melted, ABS plastic has an unmistakable foul odor that can cause (at a minimum) discomfort, and at worst physical symptoms. The medical consensus is that ABS plastic fumes are dangerous to inhale or be exposed to for both short and long periods of time. This is especially pertinent to 3D printing applications, where printers heat ABS to fabricate parts, releasing billions of particles per minute.
Without ventilation, these fumes can accumulate and cause toxicity in users. This precaution also applies to injection molding applications, where large quantities of material are melted and cooled several thousands of times in a workday, posing a serious threat.
Recycling ABS Plastic
ABS has poor resistance to solvents, greases, and UV light exposure. ABS will quickly degrade when weathered or placed in high–friction environments. ABS is non–biodegradable and produces dangerous waste if not recycled. ABS plastic is meant to be recyclable (recycling number 9). Recycled ABS material is often blended with virgin material to produce new parts.
According to a study conducted by Forbes Business Insights, the ABS market in 2019 was $25.135 billion and was projected to reach $42.809 billion by 2027.
Asia–Pacific is the market leader in ABS processing. However, the governments of different Asian countries like China, India, Vietnam, and Bangladesh are embracing reforms to grow manufacturing and involve plastic manufacturing. The demand for EVs and lightweight automobiles that reduce carbon emissions will cause ABS and other thermoplastics to gain significant market share.
Polyamides (PA) Plastics
Polymer Name: natural polyamides are proteins, such as wool and silk. Artificial polyamides are nylons, Kevlar, aramids, and sodium poly–aspartate.
Found In: in industrial yarn and textile fibers to make hosiery, pants, tights, leggings, stockings, coats, sweaters, underwear, sportswear, swimwear, fleece, circular knits, shoes, accessories. Some polyamide fabrics are made of various material mixtures such as spandex (elastane), or Lycra. Polyamide fabric is used in creating cooking utensils, rugs, carpets, curtains, food packaging, outdoor furniture, industrial materials, parachutes, gun parts, umbrellas, fishing nets, tires, seat belts, sleeping bags, tents, ropes, tennis rackets, machine gears, etc. Industrial applications of polyamide (PA) include:
- Automobile: polyamide can be shaped into air admission manifolds, motor covers, valve covers, and airbag holders, as well as outside segments like handles, grilles, wheel covers, and fuel covers and tops. These segments once utilized metal, but were subsequently made from polyamide as a cost–cutting measure.
- Food and Beverage: the food and refreshment industry utilizes polyamide in zones where parts may come into contact with food.
- Advanced Mechanics: polyamide is used for wire and link assurance in advanced mechanics. Polyamides are also widely used to produce 3D parts printed by selective laser sintering (SLS).
Nylon was discovered by Wallace Hume Carothers, a chemist hired by DuPont de Nemours. In 1935, he developed for the first time during the First World War, the formula known as PA–66. Typically, polyamides are made from polycondensation of diacid with a diamine or by ring–opening polymerization of lactams with 6, 11 or 12 carbon atoms. The monomers may be aliphatic, semi–aromatic or aromatic (aramids).
Polyamide and polyimide amide are not the same thing. An example of polyimide amide: Kapton.
A polyamide polymer has the following four categories: Polyamide 6 or PA–6 (or polycaprolactam), Polyamide 11 or PA–11 (a bio–based PA), Polyamide 12 or PA–12, Polyamide 66 or PA–66 (where Nylon–6 refers to Polyamide–6), and PPA (polyphthalamides, a subset of the Nylon family).
Polyamide 66 (PA–66) or Nylon 66
PA–66 is the most common form of polyamide that was originally patented by DuPont. Polyamide 66 hails from the polyamide family of aliphatic polyamides. Zytel is DuPont’s PA–66 brand name. Technyl is a plastic material from DOMO Chemicals. Its TECHNYL® 4EARTH® variant is (supposedly) the most eco–friendly PA–66.
Polyamide 6 (PA–6) or Nylon 6
The second form after PA–66 is PA–6. Ultramid® is a polyamide from BASF SE. RADIPOL® is a PA–6 brand’s name by RadiciGroup.
Polyamide 11 (PA–11) or Nylon 11
Polyamide 11 (PA–11) or Nylon 11 is a bio–based engineering plastic that is derived from plant resources (castor plants) and produced by polymerization of 11–amino undecanoic acid. Rilsan® is one of the first bio–sourced polyamides.
Polyamide 6–10 (PA–6–10)
Polyamide 6–10 (PA–6–10) is produced by the polymerization of hexamethylene diamine with a dibasic acid (sebacic acid, in this case).
Polyamide 46 (PA–46) or Nylon 46
Polyamide 46 (PA–46) or Nylon–46 is manufactured by polycondensation of adipic acid and 1,4–diaminobutane. Diaminobutane is synthesized from acrylonitrile and HCN.
Polyphthalamide (PPA)
Polyphthalamide (PPA) or High–Performance Polyamide is a high heat–resistance semi–aromatic polyamide. Defined when 55% or more of the carboxylic acid portion in the polymer chain is composed of a combination of terephthalic (TPA) and isophthalic (IPA) acids. Polyphthalamides are formed by reaction of aromatic acids with aliphatic diamines.
Differences Between Nylon, Polyamide and Polyester
Both polyamide and nylon are polymers and are classified as plastics. However, there is a difference between the two. The name Nylon was copied from the suffixes of two fibers such as cotton and rayon.
Its original name was intended to be “No–Run” which stands for unraveling or unwind. Later, the name was changed to “Nuron”, then again to “Nilon”, and finally to Nylon to clarify the pronunciation.
By definition, polyamide is a polymer of amino acids that can be both natural and artificial. Polyamide fabric is a material composition that refers to nylon fabric, and is therefore completely synthetic. This fabric is a synthetic textile composed of petroleum–based plastic polymers.
Nylon and polyamide are used interchangeably in general and mean the same thing. After its first discovery in the 1930s, Polyamide fabric is one of the most widely used synthetic fabrics today next to polyester, it is widely used in fast fashion.
Polyester differs from Nylon because it is a thermoplastic or thermoset polymer. The first polyester fiber called Terylene® was created in 1941. Synthetic polyesters are made up of dimethyl ester dimethyl terephthalate (DMT) or the purified terephthalic acid (PTA).
In contrast to natural fibers, like cotton and linen, the only advantage of polyamide fabric is its low cost. Polyamide fabric is highly detrimental to the environment. To protect humans, animals, and plants, it is best to employ a natural polyamide fiber.
Polyamide Recycling and Toxicity
The main use of PA–6 is in carpets and a recycling process for it was initially devised by DuPont in 1944, although recycling dirty carpets is still problematic at best.
Polyamide polymer can be chemically recycled or de–polymerized. This method involves breaking down the long polymer chains into monomers which can then be re–polymerized. The theory behind this idea is that de–polymerization may “possibly” convert the waste into products having a quality equivalent to that of the “virgin” polymer.
Polyamide 6 can be depolymerized to its monomer—caprolactam, by acidolysis, hydrolysis, aminolysis or catalyzed–de–polymerization in vacuum. Companies recycling PA–6 and PA–66 by depolymerization are DuPont, AlliedSignal (now Honeywell), BASF SE and Novalis Fibers.
The Takeaway
Bottom line, the less plastic you use, the better. Recyclable consumer products are part of a complex global market. Corporations are responsible for designing these single use products meant to be tossed. This is costing the consumer financially, environmentally, and physically. Because ultimately, this disposable, single–use lifestyle is unsustainable.
Sources:
What The 7 Numbers On Plastic Packaging Really Mean
https://livelovefruit.com/7-numbers-on-plastic-packaging-really-mean/
By Carly Fraser, May 20, 2015
What Do The Numbers On Recyclable Plastics Mean?
https://www.greenmatters.com/renewables/2018/09/13/ZG59GA/plastic-recycling-numbers-resin-codes
By Kristin Hunt
Which Plastics Are Recyclable By Number? – Plastics Recycling Chart
https://www.almanac.com/content/which-plastics-are-recyclable-number
By The Editors, April 23, 2018
How to Recycle Plastic Food Containers? Here Are Some Tips
https://modernfarmer.com/2018/06/how-to-recycle-plastic-food-containers/
Modern Farmer, Jun 19, 2018
Plastics
What’s recyclable, what becomes trash — and why
https://apps.npr.org/plastics-recycling/
By Rebecca Davis and Christopher Joyce, Aug. 21, 2019
Polyamide
https://www.vedantu.com/chemistry/polyamide
Polyamide (PA) or Nylon: Complete Guide (PA6, PA66, PA11, PA12…)
https://omnexus.specialchem.com/selection-guide/polyamide-pa-nylon
What is ABS Plastic | The Definitive Guide
https://plasticranger.com/what-is-abs-plastic/
May 21, 2022 by Sagar Habib
What is ABS Plastic?
Learn about the key properties, advantages, and toxicity of ABS Plastic.
https://www.xometry.com/resources/materials/abs-plastic/
By Team Xometry, April 29, 2022
Rilsan® Polyamide Family
https://www.arkema.com/global/en/products/product-finder/product-range/technicalpolymers/rilsan-product-family/
RILSAN® A DURABLE ALTERNATIVE TO STAINLESS STEEL
https://www.kerstencoating.com/coatings/rilsan/