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mercury and compounds of mercury

SPRI Emission Reporting Threshold
1.00 Kg/yr Pollutant Emissions to Air
0.1 Kg/yr Pollutant Emissions to Water
0.1 Kg/yr Pollutant Emissions to Waste Water
1.00 Kg/yr Pollutant Emissions to Land
This sheet is a generic summary, designed to give the reader a basic level of background information about the substance in question. Great care has been taken to represent as effectively and correctly as possible the broad range of (not necessarily consistent) information which is available from a variety of sources. The reader must accept therefore that this sheet has no legal status and cannot be relied upon in any legal proceedings. SEPA disclaims any responsibility or liability whatsoever for errors and omissions in this sheet.
What is it?
Mercury is a silvery white metal whic is a liquid at room temperatures. Mercury vapours are readily released from the liquid. It is odourless and non-flammable. Compounds of mercury are both organic (carbon-containing, such as methyl mercury) and inorganic (such as mercuric and mercurous chlorides).
What is it used for?
Mercury is used in thermometers, barometers, diffusion pumps, mercury-vapour lamps, advertising signs, mercury switches, batteries, electrical appliances, in the chlor-alkali industry and in dental fillings. In the past, mercury was also used in pesticides, pharmaceutical products and in paints.
Where does it come from?
In the UK, the main sources of mercury to air and water are from waste incineration, chlorine manufacture, in mercury cells, metal production, coal combustion, from dental surgeries and crematoria, from hospitals and clinics and from industrial processes using mercury and its compounds. Small amounts are released naturally from the earth's crust.
How might it affect the environment?
Mercury and compounds containing mercury are very toxic to wildlife, plants and micro-organisms. It also persists indefinitely (in various forms) in the environment. Organic compounds of mercury are accumulated by certain species in aquatic environments. Even low levels of mercury can build up to high concentrations in insects, fish and birds. The persistent nature of mercury means that it can be transported and have environmental effects at a global level.
How might exposure to it affect human health?
Mercury is toxic to humans, damaging the nervous system, lungs and kidneys. Exposure usually occurs through consumption of contaminated fish or grain, but can also occur through inhalation of mercury vapours (only likely in occupational settings). Extreme exposure following an accidental release or in occupational settings could be fatal. Some types of mercury compounds are more toxic than others: for example, methyl mercury rapidly accumulates in the brain. Exposure to both organic and inorganic forms may also be carcinogenic.
What steps are being taken to limit the potential impacts?
UK (including Scottish) legislation controlling releases of mercury are those concerned with classification of dangerous substances to surface waters; and the pollution prevention and control regulations. European Directives controlling releases of mercury include those concerned with pollution of aquatic environment by dangerous substances (76/464); restricting marketing and use of dangerous substances (76/769); treatment of hazardous waste; the management and assessment of ambient air quality; and it is also one of eleven "priority hazardous substances" in the proposed Water Framework Directive. International control is through the OSPAR convention for the protection of the marine environment of the north-east Atlantic; the UNECE convention on long-range transboundary air pollution; the UNECE heavy metals protocol; the Basel convention on transboundary movement and disposal of hazardous wastes; the Rotterdam convention on hazardous chemicals and pesticides in international trade; and it is listed as a substance for priority action on its control under the Helsinki Convention which protects the marine environment of the Baltic sea.