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DESIGNATIONS
CAS No.: 7439-97-6
Registry name: Mercury
Chemical name: Mercury
Synonyms, Trade names: Quicksilver
Chemical name (German): Quecksilber
Chemical name (French): Mercure
Appearance: silvery white, shiny metal, liquid at room temperature
BASIC CHEMICAL AND PHYSICAL DATA
| Chemical symbol: | Hg |
| Rel. atomic mass: | 200.59 g |
| Density: | 13.55 g/cm3 |
| Relative gas density: | 6.93 |
| Boiling point: | 357.3°C |
| Melting point: | -38.9°C |
| Vapour pressure: | 163 x 10-3 Pa |
| Solvolysis/solubility: | in water: 60 µg/l at 20°C, 250 µg/l at 50°C |
| Conversion factors: | 1 ppm = 8.34 mg/m3 1 mg/m3 = 0.12 ppm |
BASIC DATA OF SELECTED COMPOUNDS
| CAS No: | 7487-94-7 | 21908-53-2 |
| Chemical name: | Mercury(II) chloride | Mercury(II) oxide |
| Synonyms, Trade names: | Mercuric chloride, Calochlor | Mercuric oxide |
| Chemical name (German): | Quecksilber(II)chlorid | Quecksilber(II)oxid |
| Chemical name (French): | Chlorure de mercure (II) | Oxyde de mercure (II) |
| Appearance: | white crystalline powder | yellow to red crystalline powder (colour depends on size of crystals) |
| Empirical formula: | HgCl2 | HgO |
| Relative molecular mass: | 271,5 g | 216.59 g |
| Density: | 5.43 g/cm3 | 11.1 g/cm3 |
| Boiling point: | 303°C | |
| Melting point: | 280°C | above 400-450°C decomposition (liberation of toxic Hg vapours) |
| Vapour pressure: | 560 kPa at 280°C | 0.0012 hPa |
| Solvolysis/solubility: | in water: 74 g/l at 20°C 550 g/l at 100°C soluble in most organic solvents (alcohol, ether, benzene) |
virtually insoluble in water (0.05 mg/l) and ethanol |
ORIGIN AND USE
Usage:
Mercury is used as a cathode in the electrolysis of alkali-metal
chlorides, in the production of batteries and pesticides, in the
medical sector (amalgams and disinfectants), in the electrical
industry (bulbs and components) as well as in pressure gauges and
temperature measurement. For toxicological reasons its use in
ointments and disinfectants is no longer standard practice.
Origin/derivation:
The Earth's crust contains an average of approximately 0.02 ppm
of this element on average. Cinnabar (HgS) is the most widespread
mercury mineral.
Mercury is ubiquitous. On average, freshwater contains 0.1 m g/l, seawater 0.03 m g/l and air 0.005-0.06 ng/m3 of mercury. Both inorganic and organic mercury compounds are hazardous to the environment. The organic compounds being much more poisonous. Some 70-80% of the total environmental impact is caused by natural emissions such as volcanoes or by evaporation from the Earth's crust or the oceans. About 20-30% is due to anthropogenic sources such as the mercury processing and ore dressing industry or the combustion of fossil fuels. Although this contribution is relatively small, there is no reason to underestimate the danger of mercury at high concentrations.
Production figures:
Mining production of mercury in 1984
| USSR | 1,600 t | USA | 657 t |
| Spain | 1,520 t | Mexico | 384 t |
| China | 800 t | Algeria | 377 t |
| World | 5,814 t |
(figures from ULLMANN, 1990)
Toxicity
Characteristic effects:
Humans/mammals: In comparison with the liquid metal, mercury dusts and vapours are very toxic. It is subject to almost complete resorption via the lungs. The initial symptoms of acute poisoning are a sweet, metallic taste in the mouth together with nausea and vomiting. This is followed by inflammation of the mucous membranes in the respiratory organs. Mercury is finally stored in the liver and kidneys and is only excreted in bursts. Mercury-induced occupational diseases are subject to mandatory reporting in Germany. Chronic poisoning causes malfunction of the central nervous system, the symptoms being apathy, unretentive memory, overexcitability and general trembling. Mercury poisoning can prove fatal.
Inorganic mercury compounds
Mercury salts corrode the skin and mucous membranes. They are
usually absorbed orally or dermally because of their low
volatility. The intake of salts causes inflammation of the
throat, difficulty in swallowing, drowsiness, vomiting, stomach
pains, blood-tinged diarrhoea, circulatory collapse and shock.
There is also swelling of the salivary glands, loosening of teeth
and inflammation of the liver and kidneys.
Organic mercury compounds
Organic mercury compounds (especially alkyl mercury) are
generally much more toxic than the inorganic. Moreover, acute
poisoning by organic compounds develops completely different
symptoms. In particular, poisoning caused by short-chain alkyl
derivatives such as methyl or ethyl mercury only becomes apparent
after some time (with the exception of pathological trembling);
weeks usually pass following absorption. Typical symptoms include
a restricted field of vision, unclear pronunciation and
handwriting, abnormal hypersensitivity, irritation of the skin,
nose bleeds and depression. Exposure to organic compounds attacks
the nervous system (best-known epidemic: Minamata disease,
Japan).
Methyl mercury dissolves readily in fat and passes through the blood-brain barrier and the placenta. It has a mutagenic and teratogenic potential (as a substance with a proven foetus-damaging effect, methyl mercury is listed in pregnancy group A in Germany).
Whereas only 0.01% of the metallic and some 15% of the inorganically bonded mercury is resorbed following oral intake, the resorption of organic compounds is up to 95% (DVGW, 1985).
Plants: Mercury compounds inhibit cell growth and impair permeability.
ENVIRONMENTAL BEHAVIOUR
Water:
Mercury inhibits the metabolic activity of microorganisms and
thus suppresses the self-purification capability of water at
concentrations as low as 18 m g/l.
Mercury is adsorbed on sediment and suspended matter.
Air:
Mercury is washed out more or less completely by precipitations.
Soil:
Mercury accumulates in soil, preferably in humous soils.
Degradation, decomposition products:
Mercury is degraded by microorganisms (biomethylation) or
oxidised to form Hg2+. Methylation produces methyl
mercury in a reaction which is promoted by high pH values.
Dimethyl mercury, which is only formed chemically (chemical
methylation), escapes into the atmosphere and decomposes to form
elemental mercury. Above all, rain impacted by mercury(II) ions
can lead to the formation of monomethyl mercury out of inorganic
mercury. In addition to methylation, chelate complexes may form
from mercury(II) ions. Methyl mercury is a powerful fish toxin.
Food chain:
The mercury content may increase in plankton and aquatic animals
by up to 500 times the concentration in seawater (DVGW, 1985).
There is considerable accumulation in the food chain on account
of its accumulation in the liver and kidneys.
Combination effects:
The effect of mercury is enhanced by the simultaneous intake of
copper, zinc or lead.
ENVIRONMENTAL STANDARDS
| Medium/ acceptor | Sector | Country/ organ. | Status | Value | Cat. | Remarks | Source |
| Water: | Surface | D | L |
0.0005 mg/l | 1) | acc. DVGW, 1985 | |
| Surface | D | L |
0.001 mg/l | 2) | acc. DVGW, 1985 | ||
| Surface | EC | G |
0.0005 mg/l | 3) | acc. DVGW, 1985 | ||
| Surface | EC | G |
0.001 mg/l | 4) | acc. DVGW, 1985 | ||
| Drinkw | CDN | 0.001 mg/l | acc. DVGW, 1985 | ||||
| Drinkw | CH | 0.003 mg/l | 1980 | acc. MERIAN, 1984 | |||
| Drinkw | D | L |
0.001 mg/l | acc. DVGW, 1985 | |||
| Drinkw | EC | G |
0.001 mg/l | acc. DVGW, 1985 | |||
| Drinkw | J | 0.001 mg/l | 1968 | acc. MERIAN, 1984 | |||
| Drinkw | SU | 0.005 mg/l | 1970 | acc. MERIAN, 1984 | |||
| Drinkw | USA | (L) |
0.002 mg/l | acc. DVGW, 1985 | |||
| Drinkw | USA | (L) |
0.0005 mg/l | In State of Illinois | acc. WAITE, 1984 | ||
| Drinkw | WHO | G |
0.001 mg/l | acc. LAU-BW, 1989 | |||
| Groundw | NL | G |
0.2 µg/l | Reference | acc. BACHMANN, 1987 | ||
| Groundw | NL | L |
2 µg/l | Intervention | acc. BACHMANN, 1987 | ||
| Waste water | CH | (L) |
0.001 g/m3 | For drinking water | acc. LAU-BW, 1989 | ||
| Waste water | D | L |
0.05 g/m3 | acc. ROTH, 1989 | |||
| Irrigation | D | 2 µg/l | 5) | acc. DVGW, 1985 | |||
| Trough | D | 4 µg/l | Maximum value | acc. DVGW, 1985 | |||
| Soil: | Sewage sl. | D | L |
2 mg/kg | 6) | KLOKE, 1988 | |
| Sewage sl. | D | L |
25 mg/kg | 7) | KLOKE, 1988 | ||
| CH | G |
0.8 mg/kg | 8) | acc. BAfUB, 1987 | |||
| GB | G |
1.5 mg/kg | Domestic gardens | acc. SAUERBECK, 1986 | |||
| GB | G |
1 mg/kg | Vegetable gardens | acc. SAUERBECK, 1986 | |||
| GB | G |
50 mg/kg | 9) | acc. SAUERBECK, 1986 | |||
| NL | G |
0.3 mg/kg | Reference | acc. TERRA TECH 6/94 | |||
| NL | L |
10 mg/kg | Intervention | acc. TERRA TECH 6/94 | |||
| Air: | eMISS. | d | l |
0.2 mg/m3 | mass flow > 1 g/h13) | acc. TA Luft, 1986 | |
| DDR | L | 0.0003 mg/m3 | MIK | acc. HORN, 1989 | |||
| Workp | AUS | (L) |
0.05 mg/m3 | acc. MERIAN, 1984 | |||
| Workp | B | (L) |
0.05 mg/m3 | acc. MERIAN, 1984 | |||
| Workp | BG | (L) |
0.0003 mg/m3 | 10) | acc. MERIAN, 1984 | ||
| Workp | BG | (L) |
0.01 mg/m3 | acc. MERIAN, 1984 | |||
| Workp | CS | (L) |
0.0003 mg/m3 | 10) | acc. MERIAN, 1984 | ||
| Workp | CS | (L) |
0.05 mg/m3 | Long-time value | acc. MERIAN, 1984 | ||
| Workp | CS | (L) |
0.15 mg/m3 | Short-time value | acc. MERIAN, 1984 | ||
| Workp | D | L |
0.1 mg/m3 | MAK | Mercury | DFG, 1994 | |
| Workp | D | L |
0.01 mg/m3 | MAK | organic mercury compounds | DFG, 1994 | |
| Workp | D | L |
200 µg/l | BAT | metallic and inorg. compounds, urine | DFG, 1994 | |
| Workp | D | L |
50 µg/l | BAT | metallic and inorg. comp., whole blood | DFG, 1994 | |
| Workp | D | L |
100 µg/l | BAT | metallic and organic comp., whole blood | DFG, 1994 | |
| Workp | DDR | (L) |
0.005 mg/m3 | Long-time value | acc. HORN, 1989 | ||
| Workp | DDR | (L) |
0.01 mg/m3 | Short-time value | acc. HORN, 1989 | ||
| Workp | H | (L) |
0.02 mg/m3 | Skin | acc. MERIAN, 1984 | ||
| Workp | IL | (L) |
0.001 mg/m3 | 11) | acc. MERIAN, 1984 | ||
| Workp | J | (L) |
0.05 mg/m3 | acc. MERIAN, 1984 | |||
| Workp | NL | (L) |
0.05 mg/m3 | acc. MERIAN, 1984 | |||
| Workp | PL | (L) |
0.01 mg/m3 | acc. MERIAN, 1984 | |||
| Workp | RO | (L) |
0.001 mg/m3 | 10) | acc. MERIAN, 1984 | ||
| Workp | RO | (L) |
0.05 mg/m3 | Long time value, skin | acc. MERIAN, 1984 | ||
| Workp | RO | (L) |
0.15 mg/m3 | Short time value, skin | acc. MERIAN, 1984 | ||
| Workp | S | (L) |
0.05 mg/m3 | Skin | acc. MERIAN, 1984 | ||
| Workp | SF | (L) |
0.05 mg/m3 | acc. MERIAN, 1984 | |||
| Workp | SU | (L) |
0.01 mg/m3 | PDK | acc. SORBE, 1985 | ||
| Workp | USA | (L) |
0.01 mg/m3 | TWA | Alkyl compounds | ACGIH, 1986 | |
| Workp | USA | (L) |
0.03 mg/m3 | STEL | Alkyl compounds | ACGIH, 1986 | |
| Workp | YU | (L) |
0.0003 mg/m3 | 10) | acc. MERIAN, 1984 | ||
| Workp | YU | (L) |
0.1 mg/m3 | Skin | acc. MERIAN, 1984 | ||
| Foodstuffs: | D | G |
0.01 mg/kg | Milk, cheese | acc. GROßKLAUS, 1989 | ||
| D | G |
0.03 mg/kg | 12) | acc. GROßKLAUS, 1989 | |||
| D | G |
0.1 mg/kg | Animal's liver, kidneys | acc. GROßKLAUS, 1989 | |||
| D | G |
0.05 mg/kg | Meat, sausage products | acc. GROßKLAUS, 1989 |
Notes:
The use of mercury compounds in pesticides has likewise been
banned in the Federal Republic of Germany since 1980; their use
in cosmetics is restricted to a few exceptions and the maximum
content for fish in line with the Mercury Order (1975) is 1
mg/kg.
1) Limit value for natural treatment
2) Limit value for chemical and physical treatment
3) Guideline for physical and refined chemical treatment
4) Mandatory value for physical and refined chemical treatment
5) Maximum value for field and under-glass cultivation
6) Tolerable overall content in air-dry soil (limit value according to the Sewage Sludge Order)
7) Limit value for heavy metals in sewage sludge (limit value according to the Sewage Sludge Order)
8) Pollutant content in air-dried mineral soil (total content, HNO3 extract)
9) Public parks or open spaces
10) Limit values for mercury forming part of suspended dust
11) Provisional limit value for Israel
12) Hen's egg, beef, veal, pork, minced meat, chicken
13) Hg and its compounds, stated as Hg
Comparison/reference values
| Medium/origin | Country | Value | Source |
| Water: | |||
| Lake Constance (1982) | D | 0.003 µg/l | acc. DVGW, 1985 |
| Neckar (1982) | D | 0.1 µg/l | acc. DVGW, 1985 |
| Rhine (Cologne, 1983) | D | 0.01-0.2 µg/l | acc. DVGW, 1985 |
| Rhine (Duisburg, 1983) | D | 0.03-0.13 µg/l | acc. DVGW, 1985 |
| Danube (Leipheim, 1976) | D | 0.03 µg/l | acc. DVGW, 1985 |
| Weser (Bremen, 1979) | D | 0.025-3.8 µg/l | acc. DVGW, 1985 |
| Seawater | J | 12.5 ng/l | acc. RIPPEN, 1989 |
| North Sea | 1.9-15 ppt | acc. RIPPEN, 1989 | |
| Air: | |||
| Southern hemisphere (Africa): | 2.3 ng/m3 | acc. RIPPEN, 1989 | |
| USA: | 1.9-36 ng/m3 | acc. RIPPEN, 1989 | |
| Sediment: | |||
| Rhine (Cologne): | D | 10 mg/kg (1975-77) | acc. DVGW, 1985 |
| Neckar (Heidelberg): | D | 0.7 mg/kg (1975-77) | acc. DVGW, 1985 |
| Danube (Leipheim): | D | 1.2 mg/kg (1975-77) | acc. DVGW, 1985 |
| Port of Hamburg: | D | 11.2 mg/kg (1977) | acc. DVGW, 1985 |
| Mammals/humans: | |||
| Blood (human), normal value: | 5 - 10 ng/ml | acc. RIPPEN, 1989 | |
| Urine (humans), normal value: | 1.5-8 µg/d | acc. RIPPEN, 1989 | |
| Seals: | <100-200 mg/kg | acc. RIPPEN, 1989 | |
| Foodstuffs: | |||
| Fruit, vegetables: | 0.25-33 ppb | acc. RIPPEN, 1989 | |
| Grain: | 0.5-640 ppb | acc. RIPPEN, 1989 | |
| Meat, liver, etc.: | 0.5-1.430 ppb | acc. RIPPEN, 1989 | |
| Fish, fish products: | 0.5-2.740 ppb | acc. RIPPEN, 1989 | |
Assessment/comments
Solid mercury in the form of pure metal is not poisonous to humans and, therefore, not hazardous. However, the use of mercury alloys (amalgams) as dental fillings is under discussion. Although the release of mercury into saliva is relatively low there is a tendency towards substitution of amalgams with less toxic materials such as ceramics or plastics. Particular attention must be paid to mercury vapours as well as to water pollution. Risk assessment of mercury compounds depends on the properties of the individual substance. Mercury(II) chloride and methyl mercury are particularly significant in this sense.