Plastic has been one of the most scrutinized materials in recent years due to its detrimental (and irreversible) effects on the environment. Unfortunately, a lot of the things we use every day have a plastic component in them—even just a little. If we cannot avoid using plastic, we should thus be more critical and informed about the different types so that we can segregate and recycle accordingly.
Plastic types are indicated by the number in the “recycle logo” usually engraved in plastic containers. Contrary to popular belief, these numbers do not indicate the number of times the plastic may be reused. These numbers were proposed by the Society of the Plastics Industry code to indicate the recyclability of these plastics. These are called the plastic’s resin identification number which is from 1 to 7.
Plastic types 1 and 2 are easily recyclable. Plastic type 1 is Polyethylene Terephthalate (PET or PETE) which is often used for packing food and drink due to a property that prevents oxygen from seeping through to avoid spoilage. PET, however, contains antimony trioxide, a carcinogen, which may be released the longer a food or drink is not opened immediately.
Plastic type 2 is High-Density Polyethylene (HDPE) and is also easily recyclable. This is denser and tougher than PET and is often used in shampoo containers, grocery bags, trash bags. Due to its properties, it is considered safer; however, it might release hormone-disrupting chemicals when exposed to sunlight over extended periods.
Plastic types 3 and 4 are also recyclable, but may require more steps. The third type is Polyvinyl Chloride (PVC) and it’s usually used for plumbing pipes, toys, medical tubing, and some detergent bottles. It is incredibly toxic and should not be used for food packaging. This was the second most used plastic after PET before studies showed that disposing of PVC may release toxic chemicals like bisphenol A (BPA), phthalates, lead, dioxins (a known Persistent Organic Pollutant or POP), mercury, and cadmium. Some of these chemicals are carcinogenic and hormone-disrupting.
Plastic type 4 is Low-density Polyethylene (LDPE) which is usually present in sandwich bags, squeezable bottles (e.g. ketchup, mustard), and lining for most paper cups. LDPE produces less emissions than other plastic types because of its chemical properties; however, it also contributes the most to plastic pollution. A lot of manufacturers prefer using it because it’s cheap and easy to process.
Plastic types 5, 6, and 7 are not usually recyclable. Plastic type 5 is Polypropylene (PP) which is usually used in stiff food containers or tumblers, and even packing peanuts. It is relatively strong and can withstand microwaving.
The sixth type is Polystyrene (PS) is also known as Styrofoam which is usually used in disposable containers, but is also used in bike helmets for safety. Although it is usually used for food containers, exposure to heat and oil may release nervous system toxicants. Aside from this, PS is lightweight and flimsy, making it easily affect the environment.
The seventh type is the ‘Others’ category. Plastic under this category may be a mix of other plastics such as bioplastics. Plastics included in this type are polycarbonate, fiber glass, and nylon, among others. Polycarbonate (PC) is the most prevalent because it causes various health problems but is still widely used in baby bottles, metal can liners, and dental sealants. Efforts have been enforced to lessen PC use in baby food containers.
It is important to note that high plastic type numbers are worse for the environment because these plastic types should be reused rather than disposed of.
Plastic is a complex material but these classifications may help consumers make more informed decisions when buying plastic products.