Inorganic mercury compounds

Toxicity. Inorganic mercury compounds, aryl mercury compounds, and alkoxy mercurials are generahy considered to be quite similar in their toxicity. Alkyl mercury compounds are considered to be substantiahy more toxic and hazardous. Mercury and its compounds can be absorbed by ingestion, absorption through the skin, or by inhalation of the vapor. The metal itself, however, rarely produces any harmful effects when ingested (16). 

Alkyl mercury compounds in the blood stream are found mainly in the blood cehs, and only to a smah extent in the plasma. This is probably the result of the greater stabhity of the alkyl mercuric compounds, as well as their pecuflar solubiUty characteristics. Alkyl mercury compounds affect the central nervous system and accumulate in the brain (17,18). Elimination of alkyl mercury compounds from the body is somewhat slower than that of inorganic mercury compounds and the aryl and alkoxy mercurials. Methylmercury is eliminated from humans at a rate indicating a half-life of 50—60 d (19) inorganic mercurials leave the body according to a half-life pattern of 30—60 d (20). Elimination rates are dependent not only on the nature of the compound but also on the dosage, method of intake, and the rate of intake (21,22). 

Most inorganic mercury compounds have very low vapor pressures, and generally do not contribute to high mercury vapor readings. MetaUic mercury is the most potent and troublesome in this respect. Organic mercurials also contribute to mercury vapor readings, possibly by virtue of the presence of extremely small amounts of metallic mercury present as an impurity. 

Elemental mercury and inorganic mercury compounds human health aspects (No. 50, 2003) Ethylenediamine (No. 15, 1999)... 

Methylmercury compounds at concentrations of 25.0 mg Hg/kg in soil were fatal to all tiger worms (Eisenia foetida) in 12 weeks at 5.0 mg/kg, however, only 21% died in a similar period (Beyer et al. 1985). Inorganic mercury compounds were also toxic to earthworms (Octochaetus pattoni) in 60 days, 50% died at soil Hg levels of 0.79 mg/kg, and all died at 5.0 mg/kg (Abbasi and Soni 1983). 

Kopfler, F.C. 1974. The accumulation of organic and inorganic mercury compounds by the eastern oyster (Crassostrea virginica). Bull. Environ. Contam. Toxicol. 11 275-280. 

If a pregnant woman is affected by mercury poisoning, the consequences may affect the child. As a result, the child may suffer from profound mental deficiency, atrophy of cerebral cortex, commisure and cerebellum neuron destruction. Acrodynia is a syndrome that affects children exposed to organic and inorganic mercury compounds. Symptoms include itchy, measles-like rash followed by desquamation of palm and foot skin, essential tachycardia, generalized swellings, hypertension and salivation (Harada, 1995). 

Inorganic mercury compounds were discharged into the sea at Minamata Bay in Japan, from where they were taken up by bacteria and converted into methylmercury compounds. These bacteria entered the food chain to be taken up eventually by fish. Since fish are an important source of food in Japan, in a very short time many people died and many more were permanently affected by mercury poisoning. 

Mercrobes mercury reduction technology (Mercrobes) is a proprietary, ex situ technology for the treatment of soils, sludges, sediments, and waters contaminated with mercury and mercury compounds. The process uses proprietary microbes to reduce organic and inorganic mercury compounds to elemental mercury. The vendor claims that in addition to reducing charged... 

Organic mercury compounds, especially phenyl and methoxyethyl mercury may also be biotransformed into inorganic mercury by cleavage of the carbon-mercury bond. Although such compounds are more readily absorbed than inorganic mercury compounds, the toxicity is similar. 

HgCl2 in the presence of estuarine sediments showed distinct seasonal variation, whose rhythm apparently relates to the seasonal ability of the microorganisms to carry out biomethylation (755, 156). The ability of different river sediments to perform biomethylation depended markedly on the nature of the sediments (157, 158) thus, organic sediments reacted appreciably faster than coarse sand. Activated sludge will methylate inorganic mercury compounds under both sterile and nonsterile conditions, suggesting the presence of both biotic and abiotic pathways (159). 

Nervous System. The nervous system is also a common target of toxic metals particularly, organic metal compounds (see Chapter 16). For example, methylmercury, because it is lipid soluble, readily crosses the blood-brain barrier and enters the nervous system. By contrast, inorganic mercury compounds, which are more water soluble, are less likely to enter the nervous system and are primarily nephrotoxicants. Likewise organic lead compounds are mainly neurotoxicants, whereas the first site of inorganic lead is enzyme inhibition (e.g., enzymes involved in heme synthesis). 

Monatomic elemental mercury in the vapor state, Hg(g), is absorbed from inhaled air by the pulmonary route to the extent of about 80%. Inorganic mercury compounds are absorbed through the intestinal tract and in solution through the skin. 

The kidney is the primary target organ for Hg2+. Chronic exposure to inorganic mercury ) compounds causes proteinuria. In cases of mercury poisoning of any type, the kidney is the organ with the highest bioaccumulation of mercury. 

Figure 4.3. Biochemical mechanisms of resistance to (a) inorganic mercury compounds, (b) some...

Inorganic mercury compounds Organic mercury compounds Immunotoxidty ... 

Mercury (Hg, CAS Number 7439-97-6) is a naturally-occurring metal that has an atomic number of 80 and an atomic weight of 200.6. Many different organic and inorganic mercury compounds are found in nature because of mercury s ability to form covalent and ionic bonds with other chemicals. Mercury exists in three forms in three oxidation states (0, +1, +2) elemental mercury (Hg°), organic mercury (e.g., methyl mercury), and inorganic mercury (e.g.. 

The metabolite is eliminated mainly in urine and feces it is also excreted in milk. In humans, inorganic mercury compounds have two elimination half-lives one lasts for days or weeks and the other much longer. 

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