Elemental mercury vapor

Due to its chemical inertness, vaporizable nature (enthalpy of vaporization = 59.15 kJ/mol), and low water solubility (at 20°C, 2 x 10 6 g/g), elemental mercury vapor has over one year of residence time, long-range transport, and global distribution in the atmosphere [3-8]. 

Steffek AJ, Clayton R, Slew C et al Effects of elemental mercury vapor exposure on pregnant Sprague-Dawley rats. Teratology 35(2) 59 (abst), 1987... 

Elemental mercury vapor is relatively lipid soluble and is readily absorbed from the lungs following inhalation and is oxidized in the red blood cells to Hg2+. Elemental mercury may also be transported from red blood cells to other tissues such as the CNS. Elemental mercury readily passes across the blood-brain barrier into the CNS and also into the fetus. The metallic compound is only poorly absorbed from the gastrointestinal tract, however. 

Elemental Mercury Vapor. Although there may be toxic effects to the respiratory system from the inhalation of mercury vapor, the major toxic effect is to the CNS. This is especially true after chronic exposure. There are a variety of symptoms such as muscle tremors, personality changes, delirium, hallucination, and gingivitis. 

Penicillamine Copper, gold, lead, elemental mercury (vapor), zinc... 

Global changes and extensive industrialization during the twentieth century made animals and humans become exposed to a variety of chemicals. Exposure to chemical forms of mercury (e.g., elemental mercury vapor [Hg°], inorganic mercury [Hg+] and mercuric [Hg2+], organic mercury [R-Hg+ or R—Hg—R])... 

Although mercury has been used in spring tonics, as a cure for syphilis, and a panacea for other afflictions, it is now recognized as a highly toxic trace metal that concentrates in aquatic food webs. According to Clarkson (1997), the principal human exposure to inorganic mercury species is from elemental mercury vapor, which is derived principally from industries such as gold and silver... 

Sanemasa I. (1975) The solubihty of elemental mercury vapor in water. Bull. Chem. Soc. Japan. 48, 1975—1978. 

Dental amalgam restorations leak small amounts of elemental mercury vapor into the oral cavity of the mouth. The released mercury can be taken up by the saliva and then distributed to various organs and compartments throughout the body. Daily mercury uptake rates from amalgam are estimated to range from 2 to 25 pg Hg/24 h with the worst case individual estimated to have an uptake of 70 pg Hg/24 h. Mercury is a known neurotoxicant and the off-gassing of mercury over time may cause dementia like conditions in some people. 

Respiratory effects in animals have been observed following acute inhalation exposure of metallic mercury vapors. Rats exposed to 27 mg/m3 of elemental mercury vapors for 2 hours then observed for 15 days displayed dyspnea and death due to asphyxiation (Livardjani et al. 1991b). Respiratory tract lesions included lung edema, necrosis of the alveolar epithelium and hyaline membranes, and occasional lung fibrosis. 

Metallic Mercury. Initial exposure to high concentrations of elemental mercury vapors produces a syndrome similar to "metal fume fever," which is characterized by fatigue, fever, chills, and elevated leukocyte count. Evidence of moderate-to-high leukocytosis with neutrophilia was reported following acute inhalation exposure to metallic mercury vapor (Campbell 1948 Haddad and Sternberg 1963 ... 

Metallic Mercury. Inhalation exposure of individuals to elemental mercury vapors for acute and intermediate durations has resulted in erythematous and pruritic skin rashes (Aronow et al. 1990 Bluhm et al. 1992a Foulds et al. 1987 Karpathios et al. 1991 Schwartz et al. 1992 Sexton et al. 1976). Other dermal reactions to mercury exposure include heavy perspiration (Aronow et al. 1990 Fagala and Wigg 1992 Karpathios et al. 1991 Sexton et al. 1976) and reddened and/or peeling skin on the palms of the hands and soles of the feet (Aronow et al. 1990 Fagala and Wigg 1992 Karpathios et al. 1991). 

No information was located regarding specific concentrations of elemental mercury vapor that may be lethal however, lethal exposures have generally occurred as a result of exposure under conditions in which exposure levels are likely to be quite high (e.g., heating metallic mercury in a closed space). 

Musculoskeletal Effects. Increases in tremors, muscle fasciculations, myoclonus, or muscle pains have been reported in persons exposed to unspecified concentrations of elemental mercury vapor (Adams et al. 1983 Albers et al. 1982, 1988 Aronow et al. 1990 Barber 1978 Bidstrup et al. 1951 Bluhm et al. 

Bullock (1997) used the Regional Lagrangian Model of Air Pollution (RELMAP) to simulate the emission, transport, chemical transformation, and wet and dry deposition of elemental mercury gas, divalent mercury gas, and particulate mercury from various point and area source types to develop an atmospheric mercury emissions inventory by anthropogenic source type. The results of the RELMAP model are shown in Table 5-3. On a percentage basis, various combustion processes (medical waste incinerators, municipal waste incinerators, electric utility power production [fossil fuel burning] and nonutility power and heat generation) account for 83% of all anthropogenic emissions in the United States. Overall, of the emissions produced, 41% were associated with elemental mercury vapor (Hg°), 41% with the mercuric form (Hg2+), and 18% was mercury associated with particulates. 

Hg° = elemental mercury vapor Hg2+ = mercuric form Hgp= mercury associated with particulates... 

Source of exposure Elemental mercury vapor Inorganic mercury compounds Methylmercury... 

In recent years, increasing attention has been paid to human exposure to mercury via dental amalgams (Skare 1995). Exposure results from elemental mercury vapor released from amalgams that is either inhaled directly or swallowed after dissolution in saliva. A Jerome 511 Gold Film Mercury Vapor Analyzer (Arizona Instrument Corp., Jerome, AZ) has been used to measure mercury vapor released from amalgam during routine dental procedures (Engle et al. 1992) or at other times to establish baseline... 

Jerome 43IX Mercury Vapor Analyzer) was used by Chien et al. (1996) to measure elemental mercury vapor released from dental amalgams in the oral cavity and was reported to have a sensitivity of 0.003 mg/m3. Absorbed mercury can be measured using blood and urine measurements as described below. 

Cherian MG, Clarkson TW. 1976. Biochemical changes in rat kidney on exposure to elemental mercury vapor Effect on biosynthesis of metallothionein. Chem Biol Interact 12 109-120. 

Molin M, Schutz A, Skerfving S, et al. 1991. Mobilized mercury in subjects with varying exposure to elemental mercury-vapor. Int Arch Occup Environ Health 63(3) 187-192. 

There is no known biochemical reaction in organisms that applies Hg as an essential element. Mercury is the only metal which is a liquid at ordinary temperatures. The boiling point of this metal is 357 °C. This temperature is relatively low for metals and its vapor pressure is significant even at room temperature. The threshold limit value (TLV) of elemental mercury is 0.05 mg/m- a value that is less than the equilibrium vapor pressure at ambient temperatures. However, in the mercury miners in Sicily, where the mercury occurs in shales, the miners are exposed to elemental mercury vapor, which content in the air may reach toxic levels of about 5 mg/nr Another source of exposure in mines is the mercury-containing dust. 

Riley, D. M., Newby, C. A., Leal-Almeraz, T. O., and Thomas, V. M. (2001). Assessing elemental mercury vapor exposure from cultural and religious practices. Environ Health Perspect 109, 779-784. 

Elemental mercury vapor can enter the body through inhalation and be carried by the bloodstream to the brain, where it penetrates the blood-brain barrier. It disrupts metabolic processes in the brain causing tremor and psychopathological symptoms such as insomnia, shyness, depression, and irritability. Divalent ionic mercury, Hg +, damages the kidney. Organometallic mercury compounds such as dimethylmercury, Hg(CH3)2, are also very toxic. 

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