Rating of plastics

Every day we use a lot of things made of plastic like water bottles, food containers etc. You might have also noticed a number at the bottom of water bottles or any other plastic container. Plastic manufactures follow a coding system and a number you see at the bottom of the product helps identify the polymer type it is made of.

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The coding system was developed by the Society of the Plastics Industry (SPI) in 1988, and is used internationally. The number or the SPI code as it is called talks about the quality of the plastic. Understanding the different codes helps us take appropriate decision when buying plastic products and also allows an efficient separation of items for recycling process.

We have heard about PET bottles. Plastics with SPI code of 1 is made of polyethylene terephthalate called as PET. Bottles of all kinds like beverages, syrup, jam etc, combs and rope are made from this type. It is not harmful as long as the items are not recycled and used again for the same purpose.

Plastics marked with SPI code 2 is made of high density polyethylene (HDPE). Tupperware containers are made from this type too as it is considered very safe. Items commonly made from this type include milk containers, shampoo/detergents/soap bottles and folding chairs/tables. This type can be recycled. 

Plastics of SPI code 3 is made of Polyvinyl chloride (PVC). It is one of the most toxic plastic and hence it is not suitable to make food containers. It is commonly used to make all kinds of plumbing pipes and cannot be recycled.

Plastics with SPI code 4 is made with low density polyethylene (LDPE). It is both durable and flexible.
Tupperware, sandwich bags, squeezable bottles, and plastic grocery bags are all made from LDPE. Recycled LDPE is used to make garbage cans, lumber, furniture, and more. Plastics of SPI code 3 cannot be recycled and 4 is normally not recycled.

Plastics with SPI code 5 is made of polypropylene. It is strong and has a high resistance to heat. Most of the containers of this type are microwave and dishwasher safe. Plastic cups, baby bottles, Tupperware, yogurt boxes etc. Recycled plastics of this type can be used to make rakes and ice scrappers.

Plastics with SPI code 6 is made of polystyrene (PS) and are commonly called Styrofoam. Disposable coffee cups, sweet boxes, disposable cutlery items, packing foam, CD/DVD cases are made from PS. Prolonged exposure to small quantities of styrene can cause ill-effects on our health. It can be recycled. 

Plastics with code 7 are made of polycarbonate (PC) or polyactide. It is used to make baby bottles, electrical wiring, and CD/DVD cases. It is better to avoid the use of this type of plastic for food containers because researchers believe that a toxic chemical called Bisphenol-a (BPA) to be found in a large number of consumer goods made of this plastic. BPA is the main component of polycarbonates that can cause health problems including birth defects, cancer etc. 

Whether recyclable or not, for a greener environment we must try to avoid use of plastics as much as possible and ensure proper disposal of the same.

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