University of Vermont

Recycling & Waste Management

Mercury Thermometers

Mercury (Thermometers)

thermometerMercury (metallic), also called elemental mercury or "quicksilver", is found on the UVM campus in laboratory thermometers, old thermostats, mercury switches and manometers.  It can also be found in medical instruments, electrical equipment, old chest freezers, barometers and pharmaceuticals (thimerosal).  This fact sheet deals only with metallic mercury in its liquid form.


Metallic mercury is an unusual metal because it is a liquid rather than a solid,  and it slowly evaporates at room temperature, where it easily changes into a vapor. Mercury has no odor. Mercury can combine with other chemicals to form organic (carbon-containing) or inorganic mercury compounds.  

When a mercury thermometer breaks in a lab, workers can be exposed to dangerous mercury fumes. Drops of the liquid metal tend to roll quickly and become lodged in floor cracks and behind equipment. A mercury spill is more dangerous when mercury thermometers break in ovens or incubators because mercury evaporates readily at high temperatures, creating high mercury concentrations.

Hg_switch Exposure to mercury usually occurs by breathing in mercury vapors, which are easily absorbed through the lungs into the body.  Liquid mercury is not well absorbed through the skin.  However, harmful absorption can occur through broken or damaged skin, or if there is lengthy skin contact.

Most effects of mercury exposure develop slowly over time.  Symptoms usually occur only after repeated overexposure.  These effects include insomnia, loss of appetite, nausea, weakness, and muscle tremors. Brief exposures to very high levels of mercury vapors can affect the lungs.

Overexposure of very high levels of mercury can permanently damage any of the following: the nervous system, kidneys, lungs, eyes, nose & throat or skin.  Nursing women should also avoid exposure to mercury, since inhaled mercury can enter a woman's breast milk.

Disposal of mercury thermometers and the contaminated clean-up materials generated by a spill is very expensive.

mad-hatterAn interesting note: In the past, mercury was used in felt hat production.  Felt hat manufacturers suffered from many symptoms of high-level mercury exposure, as witnessed in the Mad Hatter character in Alice in Wonderland, and the popular phrase "mad as a hatter."

Disposal at UVM

UVM has a free mercury thermometer exchange program to keep metallic mercury out of the laboratories.  Go to:  to learn more.  For pickup any other mercury-containing item, use a Laboratory Waste tag and enter the tag online at 

Final Destination

Metallic mercury, mercury spill debris and any inorganic mercury compounds get retorted.  Retorting is very expensive.  Retort facilities heat mercury at 600°F or above, forcing it into a vapor phase. The vapor is pulled on vacuum through distillation coils and cooled to liquefy, then filtered to purify. Generally, mercury is removed from the contaminated spill debris and other waste material using a Retort or other Thermal process.  Organic mercury compounds are incinerated.

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Last modified March 02 2011 04:35 PM

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