Mercury
Guidance Notes
April 2009
Safety Services Office
MERCURY: GUIDANCE NOTES
1. Introduction
1.1 Properties and uses of mercury
1.2 Toxicity of mercury
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2. General guidance on mercury
2.1 Use
2.2 Storage
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3. Spillages
3.1 Spillages at room temperature
3.2 Spillages at elevated temperature
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4. Additional notes on cleaning any mercury spillage
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5. Further Details
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1. Introduction
1.1
Properties and Uses
Mercury is a liquid metal at room temperature. It is highly toxic and is
capable of being absorbed through the skin, lungs and gastrointestinal
system.
It is widely used in thermometers, barometers,
sphygmomanometers and vacuum lines. It is being phased out of use in all
these pieces of equipment, however a lot are still in use, and they can get
broken and the mercury spilt. It is important that any spillage is cleared up
quickly and efficiently.
1.2
Toxicity of mercury
Mercury has both chronic and acute effects on the body. Chronic poisoning
occurs by low concentrations of vapour in air being breathed in over a long
period of time, possibly from bad housekeeping where spillages have not
been cleaned up. The symptoms generally manifest in the nervous system.
Acute mercury poisoning occurs by intakes of large amounts of mercury in a
short period of time. The response is manifested mainly in the respiratory
system.
2. Guidance on Use of Mercury
2.1
Use of mercury
The use of uncontained mercury should be avoided as far as possible. If
mercury is used however, a risk assessment for the work must be carried out
prior to work starting, and emergency plans must be in place for dealing with
any spills.
All users of equipment containing mercury must know where a spill kit is and
be aware of how to use it. The clean-up procedure must be included in the
induction all workers must have before starting laboratory work, and be
included in the risk assessments for using equipment containing mercury.
2.2
Transport of mercury
Mercury is heavy, so should not be stored in glass bottles greater than 500 ml
in volume. Storage in plastic bottles should be no greater than 250 ml. Upon
transportation of mercury, bottles should be placed within larger transit
containers and always supported from underneath.
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3. Spillages
In all cases of a spillage, the laboratory safety supervisor or departmental safety
officer should be informed as soon as possible, and an accident/incident report must
be completed and sent to the Safety Services office.
3.1 Spillages at Room Temperature
When dealing with spillages of mercury at room temperature, the following
procedure should be followed:
Ensure the area is well ventilated
Close off the area to prevent spreading contamination into a wider
area
Wear protective clothing, including gloves (non-latex – e.g. nitrile)
Gather as much mercury as possible together using a straight edge.
The larger the drops of mercury, the smaller the surface area to mass
ratio, and the lower the evaporation will be
During warm weather (or with large spills) avoid breathing too close
to the mercury surface. Consider using respiratory equipment with
mercury
vapour
filters
(available
from
Draeger
Ltd:
http://www.draeger.com)
Collect up the mercury by using either a foam spill collector, a vacuum
pump fitted with a water trap, a syringe, a small brush, wet paper or
adhesive tape – whatever is available
Spilt mercury will find its way into all cracks and joints in the benches
or floors, and it is unlikely to be able to be retrieved safely using
mechanical means. In these circumstances the affected area(s)
should be covered with flowers of sulphur and left for 24 hours. This
converts the mercury to far less volatile mercury sulphide. This
should then be cleaned up (avoiding raising dust), and disposed of as
chemical waste.
Zinc powder can be used instead of flowers of sulphur to amalgamate
with the mercury. Again, this should be left for 24 hours, treated as
above, then disposed of via the chemical waste disposal route.
All equipment used/affected by the spillage should be cleaned prior to
next use
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All materials used for cleaning should be treated as contaminated
waste. Items should be bagged and the bags sealed. Mercury should
not be disposed of down the sink or in normal domestic waste. It
must be disposed of via an authorised disposal contractor.
Where required, air monitoring should be carried out to ensure
mercury levels are below 0.025 mg per m3. This value refers to the
2002 Occupational Exposure Standard (OES). Air monitoring can be
carried out using a standard Draeger test kit.
3.2 Spillages at elevated temperatures
(e.g. in a hot oven)
If you suspect that mercury has been released in a hot oven, the following
procedure should be followed:
DO NOT open the over door whilst the oven is hot
Turn off the oven and vacate the area until the oven has cooled to
room temperature (24 h). Ventilate the area well during this time.
Arrange for air monitoring to ensure atmospheric mercury levels are
below 0.025 mg per m3.
Wash all surfaces – including ceilings, floors etc –with dilute nitric acid
(2N) to remove any condensed mercury (grey condensate), then use
conventional cleaning solutions. You might consider a specialist
contractor for this task. Allow to dry and re-test the atmosphere for
atmospheric mercury levels.
4. Additional notes on cleaning any mercury spillage
A variety of specialist kits are available for collection of mercury following a spillage.
These can be purchased from various laboratory supply companies such as Camlab
(http://www.camlab.co.uk/) and Fisher (http://www.fisher.co.uk)
Domestic vacuum cleaners must not be used to clean mercury spillages. They spread
mercury vapour more widely and will not be cleanable afterwards.
Carpets on which mercury has been spilt must be discarded immediately and sent to
a specialist disposal contractor
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Laboratory ovens or any other heating equipment must be withdrawn from use
immediately if mercury is spilt on them. Consult your laboratory safety supervisor
and departmental safety officer on cleaning the items before disposal.
5. Further Details
If you require any further details on working with mercury, please contact your
Departmental Safety Officer, or the University Biological and Chemical Safety Officer
(http://www.le.ac.uk/safety/staff.html)
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