? Why ban the production of mercury thermometers?
Recently, the State Drug Administration issued a notice, January 1, 2026, a complete ban on the production of mercury-containing thermometers and mercury-containing sphygmomanometer products.
This means that in a few years we will have to say goodbye to the mercury thermometers that have been with us for generations.
a
Mercury, commonly known as mercury because it has the fluidity of water and the luster of metallic silver, is a metal that exists in liquid form at room temperature.
The freezing point of mercury is ?38.83 °C, which means that it is only at this temperature and below that it becomes hard like other metals.
Why is mercury used to make thermometers?
In fact, any substance whose properties change markedly with temperature can be used to represent a temperature measurement, and the change in volume of mercury fits this description.
b
Before mercury, other liquid thermometers like water and alcohol existed, but they weren't as accurate or stable as mercury.
Of course, this is in terms of volume changes, but we can also base thermometers on color changes, such as blue for low temperatures and red for high temperatures.
By far, mercury thermometers are the most widely used in daily life.
Toxicity of mercury
Pure mercury is poisonous, and its toxicity is manifested in the fact that it can cause brain and liver damage when we take it orally, inhale it, or come into contact with it.
In addition to this, most of the compounds and salts of mercury contain high levels of toxicity.
One of the things we should be aware of about mercury is that it evaporates at room temperature.
This means that even when not heated, mercury can turn into mercury vapor and be easily inhaled.
Mercury vapor, when inhaled, can form organic compounds in the body that are the source of deadly toxicity. Dimethylmercury, for example, ? just a few microliters in contact with the skin can kill a person.
Mercury can accumulate in living organisms, and it is readily absorbed through the skin as well as the digestive and respiratory tracts.
Minamata disease, mentioned at the beginning, is organic mercury poisoning, but the more detailed process is that industrial discharges of mercury-containing wastewater contaminate the marine environment, allowing mercury to gradually build up in the bodies of those marine organisms that depend on the ocean for their livelihoods.
When nearby fishermen ate the seafood, more mercury was "passed on" to them, and the higher levels led to a more serious condition.
c
Mercury not only destroys the body's central nervous system, but also has adverse effects on the mouth, teeth and mucous membranes. Prolonged exposure to high levels of mercury can lead to brain damage and death.