At present, the water bottles on the market are mainly divided into glass, plastic, aluminum and stainless steel water bottles according to their materials. The glass water cups are not easy to carry because they are fragile and heavy. Plastic water bottles can be divided into PP, PC, and PET materials. Common water bottles, space cups, and baby bottles are mostly made of PC. When heated and exposed to direct sunlight, they can easily release toxic bisphenol A (BPA). BPA is dangerous to babies. The sex is particularly high. Many countries in Europe and the United States have included BPA in the list of prohibited chemicals. Only PP water bottles (with the BPAFRee logo) can be used safely.