Don't use this thermos anymore, it may cause chronic poisoning

Which type of thermos cannot be used?
Most insulated cups are made of stainless steel material, which is resistant to high temperatures and has good insulation performance. In stainless steel materials, there are three common "codes", namely 201, 304, and 316.
Insulated cups cannot use 201 material
201 stainless steel is not a food grade material, but an industrial product material, mostly used for making decorative tubes, industrial tubes, and watch straps.
201 stainless steel has a high manganese content and poor corrosion resistance. If it is used as the inner liner of a thermos cup, long-term storage of beverages can lead to the precipitation of manganese elements, and hot water may directly become "toxic water". Manganese metal is an essential trace element for the human body, but excessive intake of manganese can harm the body, especially the nervous system.
The Beijing Consumers Association once evaluated about 50 types of insulated cups, and the results showed that 19 types of insulated cups were marked as "unqualified products" due to excessive heavy metal content. These unqualified insulated cups mostly use non-standard stainless steel materials, namely 201 material.