Mercury Information
Elemental, liquid mercury is slightly toxic, while its vapor, compounds and
salts are highly toxic and have been implicated as causing brain and liver
damage when ingested, inhaled or contacted. For this reason (along with
exaggeration of the actual risk in the media), most thermometers now use
pigmented alcohol instead of mercury, though some medical thermometers still
use mercury for reasons of accuracy.
The main dangers associated with elemental mercury are that at STP, mercury
tends to oxidize forming mercury (II) oxide, and that if dropped or
disturbed, mercury will form microscopic drops, increasing its surface area
dramatically.
Even though it is far less toxic than its compounds, elemental mercury still
poses significant environmental pollution and remediation problems due to
the fact that mercury forms organic compounds inside of living organisms.
Methyl mercury works its way up the food chain, reaching high concentrations
among populations of some species such as tuna. Mercury poisoning in humans
will result from persistent consumption of tainted foodstuffs.
One of the most dangerous mercury compounds, dimethylmercury, is so toxic
that even a few microliters spilled on the skin can cause death.
Mercury is a bioaccumulative toxin that is easily absorbed through the skin,
respiratory and gastrointestinal tissues. Minamata disease is a form of
mercury poisoning. Mercury attacks the central nervous system and adversely
affects the mouth, gums, and teeth. High exposure over long periods of time
will result in brain damage and ultimately death. It can pose a major health
risk to the unborn fetus. Air saturated with mercury vapor at room
temperature is at a concentration many times the toxic level, despite the
high boiling point (the danger is increased at higher temperatures).
Mercury should therefore be handled with great care. Containers of mercury
need to be covered securely to avoid spillage and evaporation. Heating of
mercury or mercury compounds should always be done under a well-ventilated,
filtered hood. Additionally, some oxides can decompose into elemental
mercury, which immediately evaporates and may not be apparent.
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