No. 104 - Miljøstyrelsen

4 Health assessment of mercury
vapours
Manufacturers/importers contacted in connection with the survey have stated
that mercury used in compact and straight fluorescent lamps is either metallic
mercury or mercury amalgam.
If one or more compact or straight fluorescent lamps break in a home,
mercury vapour may be released to the indoor air, as long as the residues have
not been removed completely. Therefore, this health assessment has main
focus on exposure to mercury vapour through inhalation.
4.1 Description of mercury
Mercury (Hg) is a metallic element that may occur as the free metal or in
inorganic and metal organic compounds. Furthermore, mercury can be mixed
with other metals forming amalgams, for example with silver and copper for
dental fillings. Inorganic compounds are found in the oxidation levels +1 and
2+
+2 as mercury(I) (mercurous, Hg ) and mercury(II) (mercuric, Hg 2
2+
) salts.
Some salts readily dissolve in water, such as mercury(II) nitrate, and others
such as mercury(II) sulfide are completely insoluble. Metal organic mercury
compounds are insoluble in water, but dissolve in certain organic solvents.
Mercury (Hg 0 ) is the only metal that is liquid under normal pressure and
temperature. It appears as a heavy, odour-free silvery liquid, which is
practically insoluble in water and has a relatively high vapour pressure at room
temperature. Occurrence of liquid mercury will therefore result in exposure to
the invisible and odour-free mercury vapours. At room temperature air
saturated with mercury will have a concentration of around 14 mg Hg/m 3 or
500 times the current occupational threshold limit value. Mercury vapours are
seven times heavier than air and will disperse along the floor in a room with
insufficient ventilation (Clarkson et al., 2003).
Identification
Chemical name Mercury (metallic mercury)
CAS No. 7439-97-6
EINECS Nr. 231-106-7
Gross formula Hg
Molecular weight 200.59 g/mol
Atomic number 80
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