1. Brine, from the chemical composition analysis, contains magnesium chloride, and magnesium is one of the minerals needed by the human body, and proper intake is beneficial to the body, but if it is ingested in large quantities, it will cause poisoning. In the story, "Yang Bailao" committed suicide by drinking brine is magnesium ion poisoning after taking it in large quantities.

2. The old brine used in some time-honored shops will be constantly added with new water and new ingredients and condiments, so each time it is equivalent to drinking a part of a glass of water and then adding that part of water. In this process, harmful substances such as nitrite and heavy metals in the old brine will be continuously diluted, and the old brine will be boiled and heated every day, so microorganisms such as bacteria and viruses are difficult to survive, so the old brine will not endanger human health.

3. However, it has also been suggested that people in the tofu shop still use brine to order tofu, which will not hurt their health. Actually, the bittern used to order tofu is also called bittern, which is the liquid oozing from the salt-making process. The main component is magnesium dioxide, followed by sodium chloride and potassium chloride. Bittern has the characteristics of solidifying protein. People use a small amount of bittern to order tofu and make tofu mainly to separate protein from water, which will not cause people poisoning.

Highly mineralized water. It is often used to extract some chemical raw materials, such as salt, iodine, boron and bromine. Zigong, Sichuan, China is famous for its rich brine since ancient times.

People's Daily Online-Will there be toxic substances in brine?