Why has mercury been replaced in many thermometers and electrical devices?

Mercury has been replaced in many thermometers, electrical devices, and industrial processes primarily due to its high toxicity. While its unique physical properties—such as its liquid state at room temperature, uniform volume expansion, and high electrical conductivity—historically made it ideal for these applications, the significant health risks associated with exposure to mercury metal, vapours, and compounds have necessitated safer alternatives.12

The dangers of mercury are well-documented:
* Health Risks: Inhalation of vapours or ingestion of mercury compounds can lead to severe mercury poisoning, causing damage to the central nervous system, kidneys, and digestive tract.31
* Environmental Impact: Mercury released into the environment can bioaccumulate in the food chain, leading to toxic levels in aquatic life and posing serious risks to human health, as seen in historical incidents like Minamata disease.34

Consequently, mercury thermometers have been supplanted by electronic digital thermometers, and mercury-cell plants for industrial chemical production have been largely phased out in favor of safer, non-mercury processes.15