Mercury (Thermometers)
Mercury
(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.
Hazards
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.
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.
An 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:
http://www.uvm.edu/~esf/orderingchemicals/mercury.html
to learn
more. For pickup any other mercury-containing item, use a
Laboratory Waste tag and enter
the tag online at http://esf.uvm.edu/tags_entry/
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.
[Return to Recycling
& Waste Disposal Guide]