Plastic production accelerated rapidly after its discovery, outpacing the production of almost every other material made by man. However, concerns over plastic waste began to rise, and in the 1980s, the plastic industry started encouraging municipalities to collect and process recyclable materials.
There are many different types of plastic and this can make recycling difficult. A coding system is used by recyclers to sort the plastics to process them and different numbers or resin identification codes appear under plastic products.
The number depends on the physical properties, chemical properties and the polymer types from which plastics are made. The number system also helps consumers to make more informed decisions related to health and the environment.
There’s a misconception that the “chasing arrows” symbol means that the product is recyclable and this is not always the case. Another misconception is that the numbers relate to the number of times the plastic can be recycled. Read on to find out what the numbers really mean.
A brief look at how plastics are made
In the early 20th century, plastics were quite a novelty – there were only a few of them with limited uses. Go forward a hundred years and there are many different types of plastics and thousands of uses for them. Major chemical companies have invested in researching and developing new polymers.
Plastics are flexible and yet some of them are strong and long-lasting. They are also relatively inexpensive. We can mold them into pretty much anything, from toothbrushes to car parts.
Most plastics are synthetic, designed and engineered under artificial conditions. Today plastics, or polymers, are made mostly from crude oil. A polymer is rather like a long train made of many trucks. The trucks are monomers and the whole train, made up of many identical trucks, is the polymer.
Crude oil is made up of chemicals that need separating and, in this process, the raw material for plastics is created. To make plastic, the chemicals from the oil are heated under pressure. This causes them to stick together and they are made into pellets.
The pellets are transported to factories where the final products are made. The pellets are loaded into a machine, heated and shaped by one or more processes to make the finished product.
The shaping processes may include squirting hot plastic through a nozzle into a mold to make items like plastic bottles, squashing the plastic between heavy rollers to make plastic sheets or forcing it through a small sieve to make thin fibers.
Generally, plastics are easy to make into items of all kinds of sizes, shapes and colors. They are relatively inexpensive and can be lightweight, waterproof and electrically insulating. It is hard to imagine living without them but we need to solve the problems that come with them, such as the Great Pacific Garbage Patch, a huge area of floating plastic in the North Pacific Ocean.
One solution is to educate people to make them think twice about littering or buying items that use plastic packaging. Another solution is to recycle more plastic. The plastic has to be sorted to prevent contamination when recycling it, hence the following coding system.
#1 – PET (Polyethylene Terephthalate)
PET is one of the most common polymers, usually used for packaging of food and beverages. It is used for water bottles, carbonated drinks bottles, plastic jars, etc. It should only be used once as repeated use can increase the risk of bacterial growth and leaching.
This plastic is recyclable and is crushed and shredded into small flakes to reprocess it into other useful products like the fiber used in pillows, packaging and even new bottles.
PET plastics are used for about 96% of all plastic bottles and containers and yet only 25% are recycled. Think about switching to reusable alternatives to plastic food packaging and beverage containers.
#2 – HDPE (High-Density Polyethylene)
HDPE is a stiff, strong form of plastic used to make detergent bottles, oil bottles, shampoo bottles, and toys. It is one of the safest and most commonly recycled plastics. Recycling it for secondary use is relatively cost-effective and simple. It can be used to make waste bins, picnic tables, park benches and other products that need to be weather-resistant and durable.
In the U.S., only about 30-35% of HDPE plastic gets recycled every year, so it’s wise to try and cut down on its use.
#3 – PVC (Polyvinyl Chloride)
PVC is a sturdy plastic used to make tamper-proof medicine seals, sheathing material for computer cables, clear plastic food wrapping, toys and a myriad of other consumer products. As it is relatively impervious to weather and sunlight, it is often used for window frames, gutters and garden hoses.
Products made using PVC plastic are difficult to recycle, requiring special machinery, and less than 1% of them are recycled.
This plastic is called the “poison plastic” because it contains a number of toxins that can leach from it over its life cycle. Try to replace plastic toys with ones like woolen stuffed animals and plastic food wrap with reusable beeswax wrap.
#4 – LDPE (Low-Density Polyethylene)
LDPE is found in grocery bags, sandwich bags, dry cleaner garment bags, shrink wraps and cling film. Most of the plastic bags used in stores are made from LDPE.
LDPE plastics are considered relatively safe to use as they are less toxic than other plastics. They not commonly recycled but this is changing today as more plastic recycling programs are now able to handle them. When recycled, LDPE plastic is used for items like plastic lumber, floor tiles, and garbage can liners.
Products made using LDPE plastic are reusable, but are not always recyclable. You need to check to see if LDPE items are accepted for recycling.
Take cloth bags to the store to collect your groceries or when you go to the bakery for a loaf of bread. Replace plastic sandwich bags with alternatives.
#5 – PP (Polypropylene)
PP is a lightweight and tough plastic with great heat resistance. This is the plastic that keeps your cereal fresh and dry. It is commonly used for plastic bottle tops, yogurt containers, disposable diapers, straws, and potato chip bags, serving as a barrier against grease, moisture, and chemicals.
This type of plastic is considered safe for re-use but only about 3% is being recycled in the U.S. However, it is becoming more accepted by recyclers today.
Cutting down on this type of plastic may mean opting for cloth diapers and reusable straws.
#6 – PS (Polystyrene)
Polystyrene is a lightweight, inexpensive plastic with many uses. It is often used to make take-out food containers, disposable Styrofoam cups, egg cartons, foam packaging, and foam chips.
As it is very lightweight and structurally weak, it breaks up easily and scatters throughout the natural environment. Many marine species ingest this type of plastic to their detriment. Polystyrene may leach styrene into food products, especially when heated in a microwave, and this is a possible carcinogen.
Many curbside collection services do not accept polystyrene, which is why this material often goes into a landfill. The technology for recycling is available but the market is small.
Avoid using polystyrene wherever possible. Some businesses providing shipping services accept foam packing chips for reuse.
#7 – Other (BPA, Polycarbonate, and LEXAN)
Polycarbonate and various “other” plastics are used to make items like sippy cups, baby bottles, water cooler bottles, and car parts.
Many BPA products fall into this category. Additives, like bisphenol A (BPA), may be added to plastic during manufacturing to make products more durable, transparent and flexible.
One of the main concerns is the leaching of BPA found in polycarbonate plastic food containers. Some polycarbonate water bottles are marketed as ‘non-leaching’ but there is still a possibility of small amounts leaching, particularly if they are used for heating liquids.
These plastics are not for reuse and it is better to avoid them. Plastics with the one, two and four numbers are safer choices for items used by children as they don’t contain BPA.
New compostable plastics are being developed to replace polycarbonates, and they have the initials “PLA” on the bottom near the recycling symbol or the word “compostable.” These plastics are thrown in the compost and not the recycling bin.
The last word
By understanding the numbers on our plastic, it’s possible to use them to our advantage and yet minimize waste. Think about living in a world without plastics for a moment – it’s hard to imagine. However, it’s absolutely essential to be smarter about how we make it, reuse it and recycle it.
Scientists are currently trying to make plastics safer and more sustainable. Innovators are developing bioplastics that are more environmentally friendly because they are made from plant crops instead of fossil fuels.
There are also those who are working on making plastics that are biodegradable. Wouldn’t it be great if we could continue to benefit from the use of plastic without any concerns about harming the environment or our health!