Resin Identification Code – Lets You Know Which Plastics Are Safe

Plastic materials are divided into 1-7 according to the recyclable grade. The higher the number, the better the recyclable grade, not the safer the material. Each plastic container has a number at the bottom (it is a triangle with an arrow, and there is a number inside the triangle). As shown in the figure below:

Plastic materials


“No. 1” PET is commonly used for mineral water bottles, carbonated beverage bottles, etc.

Heat resistant to 65 ℃, cold resistant to – 20 ℃, only suitable for warm or frozen drinks. It will deform when it encounters high temperature or heating and substances harmful to human body will melt out. In addition, scientists found that the carcinogen DEHP may be released from plastic No. 1 after 10 months of use. Therefore, drink bottles should be discarded when used up. Do not use them as water cups or storage containers to avoid health problems.


“No. 2” HDPE is often used for packaging of cleaning products and bath products.

It can be reused after careful cleaning, but these containers are usually not easy to clean, and the residual cleaning products will become a hotbed of bacteria, so it is better not to recycle. Don’t use it as a water cup, or as a storage container for other things.


“No. 3” PVC is commonly used for raincoats, building materials, plastic films, plastic boxes, etc., but rarely used in food packaging.

This material has good plasticity and low price, so it is widely used. However, it can only resist heat at 80 ℃, and it is easy to produce harmful substances at high temperature and even toxic substances will be released during the manufacturing process. If it enters the human body with food, it may cause breast cancer, neonatal congenital defects and other diseases. Containers of this material have been less used for packaging food.


“No. 4” LDPE is commonly used for fresh-keeping film, plastic film, etc.

The heat resistance is not strong. Generally, qualified PE film will melt when the temperature exceeds 110 ℃, leaving some plastic preparations that cannot be decomposed by human body. The oil in the food is also easy to dissolve the harmful substances in the film. Therefore, before putting food into the microwave oven, take off the wrap.


“No. 5” PP is commonly used for juice drink bottles and microwave oven lunch boxes.

The common melting point is up to 167 ℃, which is the only plastic box that can be safely put into the microwave oven. It can be reused after careful cleaning. Special attention should be paid to the fact that some microwave oven lunch boxes are indeed made of No. 5 PP (special PP for microwave oven is resistant to high temperature of 120 ℃ and low temperature of – 20 ℃), but because of the high cost, the lid is generally made of No. 1 PET without special PP. Because PET cannot withstand high temperature, it cannot be put into the microwave oven together with the box. To be safe, take off the lid before putting the container into the microwave oven.


“No. 6” PS is commonly used for bowls of instant noodles and fast food boxes.

It is heat-resistant and cold-resistant, but it cannot be put into the microwave oven to avoid the release of chemicals due to high temperature (it is released when the temperature is 70 ℃). And it cannot be used to contain strong acids (such as orange juice) and strong alkaline substances, because polystyrene, which is not good for human body. Therefore, try to avoid using fast food boxes to pack hot food.


“No. 7” PC and other types are often used for water bottles, cups and bottles.

A material widely used, especially in milk bottles, is controversial because it contains bisphenol A. Lin Hanhua, associate professor of the Department of Biology and Chemistry at the City University of Hong Kong, said that in theory, as long as bisphenol A is 100% converted into plastic structure in the process of making PC, it means that the product is completely free of bisphenol A, let alone released. However, if a small amount of bisphenol A is not converted into the plastic structure of PC, it may be released into food or drink. Therefore, it is important to be careful when using this plastic container.


The advantages of Tritan in other categories: it does not add plasticizer and bisphenol A, etc., and the healthy material is safe, but the water cup will deform when the temperature exceeds 102 ℃. You can use it with boiling water, but don’t boil it. It will deform when boiled, but it can also be used for deformation and non-toxic.



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