With the cold winter weather, many people have switched from glass cups to stainless steel ones. However, a recent online report claims that brewing Tea in a stainless steel cup can be dangerous and cause chronic poisoning, which has caught the attention of many netizens. Is brewing tea in a stainless steel cup really that scary? Yesterday, a CCTV journalist conducted an experiment to uncover the truth.
Journalist Experiment
Brewing Tea in a Stainless Steel Cup Releases Chromium
The CCTV journalist first conducted a street interview and found that many citizens were using stainless steel cups, and a number of them were using these cups for brewing tea. Many citizens mentioned that stainless steel cups are clean and hygienic, do not break when dropped, and are more suitable for drinking hot water in the colder weather. So, is it appropriate to Brew tea in a stainless steel cup? The journalist then proceeded with an experiment.
The journalist first obtained a brand new stainless steel cup and brewed tea inside it, sealing the cup tightly. After leaving it undisturbed for 72 hours, the journalist opened the stainless steel cup and noticed obvious signs of corrosion on the inner wall after flipping the cup over.
A stainless steel cup contains chromium, a heavy metal. When the protective film of a corroded stainless steel cup is damaged, chromium is released, which can harm the human body if the cup continues to be used. According to experts, chromium is a hard and brittle blue-white multivalent metal element commonly found as divalent, trivalent, and hexavalent chromium. It is hard, brittle, and corrosion-resistant, making it ideal for use in stainless steel products.
If the human body ingests large amounts of trivalent chromium over a long period, it can affect the body's antioxidant system and increase the risk of chronic oxidative diseases such as diabetes and hypertension. Additionally, damage to the antioxidant system can lead to the development of tumors and other abnormal growths. Compared to trivalent chromium, hexavalent chromium is much more toxic, approximately 100 times more so. Clinically, the harm caused by hexavalent chromium and its compounds manifests in three main ways: skin damage leading to dermatitis and pharyngitis; respiratory system damage causing pneumonia and bronchitis; and digestive system damage resulting in gastritis, gastric ulcers, and intestinal ulcers. Overexposure to hexavalent chromium can also result in renal failure and cancer.
Experts particularly advise against using stainless steel cups for brewing tea. Moreover, oils, salt, sauce, and vinegar should not be stored in stainless steel containers either.
Expert Reminder
The Lower the Quality of Stainless Steel Products, the Easier They Are to Corrode
According to experts, the quality of stainless steel cups varies, and lower-quality cups are more prone to corrosion. How can ordinary people determine the quality of stainless steel products in their daily lives? The CCTV journalist brought three stainless steel utensils from citizens' homes to the laboratory at Xihua University's School of Biotechnology. Experts used professional methods to verify the quality of the stainless steel products.
The experts first obtained a stainless steel identifier and applied it to the surface of the stainless steel products. If the identifier changes color quickly, it indicates that the stainless steel is of low quality. Conversely, the slower the change in color and the corrosion, the higher the quality of the stainless steel. The journalist observed that all the stainless steel products treated with the identifier showed some degree of corrosion, and they could not be restored to their original state despite attempts to wipe them clean. Clearly, this method is not practical for everyday use in households.
The experts then noted that an ordinary magnet could also be used to determine the quality of stainless steel. If the magnet strongly attracts the stainless steel product, it suggests that the product is almost pure iron. Since it is iron but appears shiny, it is likely an electroplated product and not genuine stainless steel. Genuine stainless steel products contain iron and have some magnetic properties, but the magnetism is weak. This is partly due to the low iron content and partly because the surface coating reduces magnetism.
Additionally, there is a simple trick to check if a stainless steel product is up to standard. First, prepare a lemon and pour lemon juice onto the surface of the stainless steel product. After about 10 minutes, wipe away the lemon juice. If there are clear marks left on the stainless steel product, it indicates poor quality and susceptibility to corrosion, which can release chromium and pose health risks.