What should I know about plastics?

Plastic is not as simple a material as it is often thought. There is not just one type of plastic material, like there is one type of cotton. This article discusses different characteristics of the material, demystifying it for the user.


Therefore, there are different types of plastics, just as there are different products that use them, such as the food industry, textiles, construction, medicine, technology, etc. Each type of plastic is a family on its own and different from other families, just like glass differs from iron, even though they are all called "plastic." Some plastics are recyclable, while others release hazardous chemicals after multiple uses. Some are easily recyclable, while others require more sophisticated and complex treatments.

On the bottom or backside of a plastic product, you will find a number enclosed in a triangle with arrows. Usually, this triangle is identified as the recycling symbol. However, in plastics and in this form, this number does not indicate how many times the product has been recycled or how many times it can be used. In fact, this number indicates the type of plastic that was used to create that specific product.

For the sake of our environment and health, it is important to familiarize ourselves with the different types of plastics, their uses, and their identification codes. Knowledge in this subject helps us, as consumers, to make more informed decisions regarding our purchases, which impact our health and the environment. Additionally, it is important to be familiar with the SPI codes of a plastic product to effectively classify its different types for reuse or recycling.

Plastic recycling codes: What are SPI codes?

In 1988, the Society of the Plastics Industry (SPI) created a classification system for plastics to help consumers separate them for recycling. Today, these codes must be placed by manufacturers on all plastic products.

What are the SPI codes, and what do they tell us about plastics?

Category/Code (1) PET - Polyethylene terephthalate
Plastic with SPI code 1 is called polyethylene terephthalate. Products made from this plastic mainly absorb aromas and flavors from the packaged foods and beverages. However, this material is one of the most commonly used for essential and everyday items. PET is primarily used to create products such as water and juice bottles, various food packaging (e.g., salad containers, take-out containers), net bags, tote bags, winter jacket filling, carpets, etc.

Category/Code (2) HDPE - High-Density Polyethylene
Plastic with SPI code 2 is called high-density polyethylene. These products do not absorb aromas or flavors from the contained products. However, due to the risk of contamination, it is not safe to reuse an HDPE bottle as a food or beverage container if it initially did not contain food. (For example, shampoo bottles should not be reused to store food but can be reused to store shampoo again.) Products primarily made from HDPE include bags, trash bags, motor oil bottles, containers for hygienic products (shampoo, detergent, bleach), plastic bottle caps, tetra packs, etc.

Category/Code (3) PVC - Polyvinyl Chloride
Plastic with SPI code 3 is called polyvinyl chloride. This type of plastic should not come into contact with food as it releases hazardous and toxic chemicals. PVC is widely used in the industrial sector, such as in hydraulic and construction fields. Products created from PVC include sports flooring, water pipes, plastic food wrap, some bags, bricks, window frames, sewage pipes, shoes, gloves, etc.

Category/Code (4) LDPE - Low-Density Polyethylene
Plastic with SPI code 4 is called low-density polyethylene. This type tends to be durable and flexible, and it is believed to not release harmful chemicals, making it considered safe for food storage. Products created from LDPE include common bags, plastic film for food wrapping, various food containers, frozen food bags, flexible lid caps, squeeze bottles like ketchup and mustard bottles, etc.

Category/Code (5) PP - Polypropylene
Plastic with SPI code 5 is called polypropylene. This type is strong and can withstand high temperatures. That's why some plastic containers can be microwaved without melting. Polypropylene is mainly used for items that need to withstand high heat, such as food containers, kitchenware, take-out food packaging, disposable cups and plates, plastic furniture, chemical bottles like bathroom cleaners, first aid products, syringes, baby diapers, etc.

Category/Code (6) PS - Polystyrene
Plastic with SPI code 6 is called polystyrene. PS can be recycled, but not efficiently; its recycling requires a lot of energy, which means few facilities accept it. Therefore, it's a good idea to invest in reusable items like coffee mugs and home-cooked meals to avoid single-use coffee cups and take-out food packaging. Products primarily made from polystyrene include egg cartons, plastic plates, all containers and packaging for food ordered from restaurants or bars, foam containers, bicycle helmets, refrigerators, ovens, microwaves, electric toothbrushes, air conditioners, etc.

Code (7) Other
Plastic with SPI code 7 encompasses various types of plastics that are not included in the previous six codes. This category mainly consists of plastic blends with another material and does not have similar and homogeneous characteristics to fit the specific SPI codes. Examples of such plastics include acrylic plastic (PMMA) - a blend of glass fibers with plastic, polycarbonate (PC) - a blend of plastic with carbon, etc. Products that mostly fall under code 7 include baby feeding bottles, bottle coolers, some car parts, nylon, CDs, mobile phones, plexiglass, aircraft windows, various nut and peanut packaging, frozen food bags, etc.