Urine organic mercury

Following exposure to metallic mercury, the elimination of mercury can occur via the urine, feces, and expired air. Following exposure to inorganic mercury (mercuric), mercury is eliminated in the urine and feces. Organic mercury compounds are excreted predominantly via the feces in humans. In animals, methylmercury is excreted in the feces, and phenylmercury compounds are initially excreted in the feces and then in the urine. Organic mercury compounds are excreted predominantly in the inorganic form. Both inorganic mercury and methylmercury are excreted in breast milk. 

Ishihara, N. and Urushiyana, K., Longitudinal study of workers exposed to mercury vapor at low concentration Time course of inorganic and organic mercury concentration in urine, Toxicology and Applied Pharmacology, 155, 161-168, 1994. 

The biological half-life in humans for methyl mercury is about 70 days because elimination is slow, irregular, and individualized, there is a considerable risk of an accumulation of mercury to toxic levels. A precise relationship between atmospheric levels of alkyl mercury and concentrations of mercury in blood or urine has not been shown. Clinical observations indicate that concentrations of 50-100pg mercury/lOOml of whole blood may be associated with symptoms of intoxication concentrations around 10-20pg mercury/ 100 ml are not associated with symptoms. In a study of 20 workers engaged in the manufacture of organic mercurials and exposed for 6 years to mercury concentrations in air between 0.01 and O.lmg/m, there was no evidence of physical impairment or clinical laboratory abnormalities. Low levels of methyl mercury in the blood do not seem to affect the results of behavioral performance tests. ... 

Unithiol and succimer increase urine mercury excretion following acute or chronic elemental mercury inhalation, but the impact of such treatment on clinical outcome is unknown. Dimercaprol has been shown to redistribute mercury to the central nervous system from other tissue sites, and since the brain is a key target organ, dimercaprol should not be used in treatment of exposure to elemental or organic mercury. Limited data suggest that succimer, unithiol, and N- acetyl-L-cysteine (NAC) may enhance body clearance of methylmercury. 

New York Developing capacity to monitor for polyaromatic hydrocarbons (PAHs) in urine, polybrominated diphenyl ethers (PBDEs) in serum, organochlorine pesticides in serum, volatile organic compounds (VOCs) in blood, cotinine in saliva, trace elements in blood and urine, inorganic mercury in blood and to generate data on exposure to persistent organic pollutants (CDC 2005). 

Flame atomisation is not necessary for the atomic absorption spectrophotomehy of mercury. The cold vapour technique described here employs a reduction vessel (which may be purchased) to produce mercury vapour the vapour is led to a quartz absorption cell within the atomic absorption inshument. The method is applicable to inorganic and organic mercurial compounds in urine. 

Figure 7.8. Step sequence for the determination of total and organic mercury in urine. (Reproduced with permission of the Royal Society of Chemistry, Ref [44].)...

In humans and mice, the excretion of organic mercury occurs largely by the fecal route, and follows first-order kinetics. The whole body clearance times and blood clearance periods are longer than those for inorganic mercury with the half-life of DMM being 78 days in humans. Other excretory routes are urine, sweat, and hair. 

Mercury will cross the placental barrier. In mammalian tissue, organic mercury, especially alkyl mercury, is converted to inorganic forms but not vice versa. Inorganic forms of mercury (not organic forms) induce a metallothionein. Inorganic mercury concentrates mainly in the kidney. Organic mercury compounds, being lipid soluble, concentrate in adipose tissue and the brain. Elimination is primarily in the urine and the feces, with small amounts in breath, sweat, and saliva. 

Organic Mercury. The fecal (biliary) pathway is the predominant excretory route for methylmercury, with less than one-third of the total mercury excretion occurring through the urine, following oral and inhalation exposure (Norseth and Clarkson 1970). In humans, nearly all of the total mercury in the feces after organic mercury administration is in the inorganic form. The conversion of methylmercury to inorganic mercury is a major step that is dependent on the duration of exposure and/or the duration after cessation of exposure. 

Urine mercury measurement is reliable and simple, and it provides rapid identification of individuals with elevated mercury levels (Naleway et al. 1991). It is a more appropriate marker of inorganic mercury, because organic mercury represents only a small fraction of urinary mercury. Yoshida (1985)... 

Certain organic mercury compounds, such as phenyl mercury and methoxyalkyl mercury, are metabolized relatively fast in the human body and are excreted in urine. In contrast to methyl mercury, these compounds do not accumulate in the body nor do they cause toxicity in the central nervous system. On the other hand they affect renal function, and mercury-... 

Margel, S.and Hirsh, J. (1984) Reduction of organic mercury in water, urine, and blood by sodium borohydride for direct determination of total mercury content. Clin. Chem., 30. 243-245. 

The mercurial diuretics essentially contain in an organic molecule. They usually inhibit sodium reabsorption in the proximal tubuler and ascending loop of Henle. There may be slight effect in the distal tubule where inhibition of chloride reabsorption also occurs. The mercurials have been foimd to enhance excretion though potassium loss is less than that produced by many other diuretics. However, the overall action of mercurial diuretics is invariably increased by acidification of urine. The mercurial diuretics are not very much used in clinical practices due to their pronormced and marked side-effects viz., mercurialism, hypersensitivity and excessive diuresis which may lead to electrolyte depletion and vascular complications. Most of the mercurials are administered by intramuscular route and the availability of orally active diru etics has limited their use. 

Exposure is also affected by absorption. Even though we may come into contact with an agent, if little is taken up into the body (or absorbed), there is little effect. For example, the metallic mercury from a broken thermometer, if swallowed, is very poorly absorbed by the gut and will be excreted in the feces. However, if this same amount of mercury were allowed to evaporate and be inhaled, there would be very serious health consequences. This example shows that metabolism and excretion modify absorption. What is not absorbed (and even some of what is absorbed) may be excreted from the body by various routes, including the urine, feces, and sweat or through exhalation. Excretion reduces the effect because it lowers the amount of toxicant in the body, thus reducing exposure to sensitive organs. 

The combination of Fe2+ and H202, called Fenton s reagent, oxidizes organic material in dilute aqueous solutions. For example, organic components of urine could be destroyed in 30 min at 5()°C to release traces of mercury for analysis.17 To do so, a 50-mL sample was adjusted to pH 3-4 with 0.5 M H2S04. Then 50 xL of saturated aqueous ferrous ammonium sulfate, Fe(NH4)2(S04)2, were added, followed by 100 p,L of 30% H202. 

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