Bisphenol A can be synthesized into PC (polycarbonate) and epoxy resin. When these materials encounter high-temperature liquids, the amount of bisphenol A released can reach 55 times that under normal conditions. The acute toxicity of bisphenol A is low, and the oral half-lethal dose for mice is 3250 mg/kg. However, bisphenol A can interfere with the body's endocrine system, and people are worried that long-term trace intake of bisphenol A may lead to chronic poisoning. Due to public concerns about BPA, on April 18, 2008, Canadian Minister of National Health Tony Clement announced that the Canadian government intended to ban the import, sale and advertising of PC baby bottles containing BPA. Starting on April 18, 2008, the government issued a 60-day public comment period on this ban and will evaluate whether to take effect in October this year. Walmart announced that they will immediately stop selling food containers, baby bottles, water cups, pacifiers, etc. containing BPA in Canada. Wal-Mart will gradually withdraw from the sale of baby bottles containing bisphenol A in the United States before 2009. On the same day, Nalgene also announced that it would stop using bisphenol A in its products. Due to public health concerns, a significant number of retailers in the United States have stopped using BPA. In 2005, Patagonia stopped selling PC bottles, and in 2006, Whole