The plastic cups or mineral water bottles we usually buy in supermarkets have a triangular symbol at the bottom with a number inside. So what does this triangular symbol represent? What do the numbers inside represent? How should we choose?
Firstly, the triangular symbol at the bottom is a recyclable symbol, representing that this plastic can be recycled.

Secondly, there are numbers 1-7 inside the triangle symbol, each representing a different material and heat resistance.

   1. Triangle symbol 1: PET (polyester), a common bottled water material, is mostly used in mineral water bottles and carbonated beverage bottles. It has a heat resistance temperature of about 70 ℃, and is prone to deformation and release harmful substances to the human body beyond 70 ℃.
2. Triangle symbol 2: HDPE (high-density polyethylene), a food grade non-toxic material, is commonly used in containers for cleaning products, edible oils, and other supplies. However, it is prone to residue and difficult to clean, and is generally not recommended for reuse.
3. Triangle symbol 3: PVC (polyvinyl chloride), commonly used as a decorative material, has low toxicity and is not suitable for the food industry.
The heat-resistant temperature is 81 ℃, which will release harmful substances to the human body if exceeded.
4. Triangle symbol 4: LDPE (low-density polyethylene), commonly used in cling film, plastic bags, etc., has low heat resistance and releases harmful substances at high temperatures. Normally, qualified PE cling film will experience heat when exposed to temperatures exceeding 110 ℃, leaving behind some plastic preparations that cannot be decomposed by the human body. Moreover, wrapping food with cling film and heating it up can easily dissolve harmful substances from the cling film in the food. Therefore, do not wrap the food with plastic wrap when entering the microwave,
5. Triangle symbol 5: PP (polypropylene): commonly used in fresh-keeping boxes and meal boxes, it is the only plastic that can be placed in a microwave oven and can withstand temperatures up to 130 ℃. It should be noted that some microwave lunch boxes are indeed made of No. 5 PP for the box body, but the box cover is made of No. 1 PE. As PE cannot withstand high temperatures, it cannot be placed in the microwave together with the box body. For safety reasons, remove the lid of the container before placing it in the microwave.
6. Triangle symbol 6: PS (polystyrene): commonly used in fast food boxes, bowl shaped instant noodles boxes, etc. It is heat-resistant and cold resistant, but when the temperature is too high, it will release chemicals, so bowl shaped instant noodles cannot be directly heated in the microwave. In addition, it cannot be used to contain strong acids (such as orange juice) or strong alkaline substances, as it will decompose into polystyrene, which is harmful to the human body and can easily cause cancer. Try to avoid packaging hot food in fast food boxes as much as possible.
7. Triangle symbol 7: Other, commonly PC type, is a widely used material, especially in water bottles, cups, and baby bottles. However, it is also a controversial material because PC is prone to release toxic substances BPA (Bisphenol A) at high temperatures, which can have adverse effects on the human reproductive system and cause endocrine disorders. Associate Professor Lin Hanhua from the Department of Biology and Chemistry at City University of Hong Kong stated that theoretically, as long as bisphenol A is 100% converted into plastic structures during the production of 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 a plastic structure of PC, it may be released and enter food or beverages. Therefore, caution is paramount when using this plastic container.
It is precisely for this reason that some countries and regions have started to ban PC, which has led to the emergence of a new material number 7: Tritan (copolyester). Tritan is a new type of plastic raw material developed by an American company and has obtained certification as a food equipment material. Therefore, Tritan can be used as a raw material for baby bottles. Tritan material has many advantages, including easy cleaning, strong impact resistance, high temperature resistance, good flowability, BPA free, and stable chemical properties.
So when choosing cups and using different tableware, we should also pay attention to the number of this symbol!