1, plastic cup: Generally, the number 1-7 is printed on the bottom of plastic cup. The larger the number, the higher the quality. Common materials are No.5 PP (polypropylene) and No.7 PC (polycarbonate). PP cup has good heat resistance, melting point as high as 167℃ and relatively stable chemical properties. It is the only plastic material that can be put into a microwave oven, and the PC cup can't hold hot water, so it is not suitable for sunlight, because high temperature may release toxic bisphenol A from this material.

2. Glass: Among all materials, glass is the safest. Glass cups are usually made of inorganic silicates, which are fired at a high temperature of more than 600 degrees. Because of their relatively stable chemical composition, they will not produce harmful substances in the firing process. Moreover, the glass surface is smooth and easy to clean, and bacteria and dirt are not easy to breed on the cup wall.

3. Ceramic cups: Ceramic cups with beautiful shapes and diverse patterns are very popular among young people.

4. Enamel cup: Enamel cup is a kind of vessel with enamel inside and outside. It takes into account the advantages of metal and porcelain, which can not only prevent the iron metal inside from rusting, but also is not as fragile as porcelain.

5. Stainless steel cup: Stainless steel cup is corrosion-resistant, wear-resistant and not easy to be damaged. It is widely used as a thermos cup and is the first choice of modern people. However, because it is an alloy product, it may contain more heavy metal substances. If used improperly, these substances are easy to seep out or react chemically, which may produce harmful substances.