Elemental liquid mercury as the pure metal is surprisingly non toxic except by inhalation which can cause severe neurological symptoms but is generally non lethal.
Inorganic, ionic forms of mercury tend to cause gastrointestinal damage but don't cross the blood brain barrier.
Organic mercury compounds are quite toxic as they tend to diffuse through the body and are easily absorbed through the skin, notably methyl mercury and dimethyl mercury are the most dangerous as they form conjugates with cysteine that mimic another amino acid methionine, which is then actively distributed through the body and into the brain.
I agree with Eric Harris. Ionic mercury act as an acute poison, being caustic at the contact place (on stomach mucosa may induce voma, but in greater concentration, perforation). Organic mercury is a chronic poison and may produce irreversible toxic encephalosis
Mercury occurs in the metallic form, but that is not its only configuration; it can also chemically bond to other elements, to form more complex molecules. When Hg is bonded to carbon atoms, we have what is normally called organic mercury. Two of the most common organic mercury compounds are methylmercury (MeHg) and ethylmercury (EtHg), where Hg forms a bond with a methyl (CH3) or ethyl (CH3CH2) group, respectively; their formulas are shown in the picture on the side. X- is an anion, or an ion with more electrons than protons, which compensates for the positive charge in both.
http://www.decodedscience.com/ethyl-methyl-mercury-difference/25234
Elemental mercury is neurotoxic but because it is a liquid at room temperature it tends to form relatively large droplets than can actually pass through the alimentary canal without being absorbed. However, when elemental mercury is vaporized by heating or broken into small particles such as can occur when a spill is vacuumed up these smaller particles can be absorbed via respiratory and oral routes and enter into the system circulation. Elemental mercury crosses blood brain barrier by passive diffusion.
Dear Fadel Djamel ,
Inorganic and Organic Mercury compounds are equally dangerous for living organisms.
Find the attached article.
Regards.
Among the organic mercury compounds dimethylmercury is more toxic than methyl mercury.
The most horrible story I know of is about a prominent researcher at Dartmouth who inadvertently exposed herself to dimethylmercury while working with the compound.
Please be very cautious if you are working with this compound. FYI, "disposable latex gloves do not provide adequate protection against dimethylmercury".
http://www.nejm.org/doi/full/10.1056/NEJM199806043382305
If you want to see a fairly recent review of the toxicological literature on inorganic mercury and methylmercury, look at the comprehensive 2012 opinion from the European Food Safety Authority in the EFSA Journal 2012, 10(12): 2985, which you can access at
http://www.efsa.europa.eu/en/efsajournal/doc/2985.pdf
Although the focus for the EFSA risk assessment was on oral exposure via food (the main source of the body's exposure to organic mercury), the toxicology details in the opinion are of relevance to all routes of exposure.
With respect to ethyl- versus methyl-mercury as with all toxicants bioaccumulation is part of the reason for toxic levels being reached within the body. Ethylmercury has a much shorter half-life and does not bioaccumulate to the extent methylmercury does, so exposure to toxic levels via chronic consumption of contaminated fish etc. is less likely to occur.
Organic and inorganic mercury are much more toxic than metallic mercury
http://www.nejm.org/doi/full/10.1056/NEJM200006153422405#t=article
Mercury is not essential to living cells and performs no known biological function. The toxicity of mercury is primarily associated with ionic Hg(II). However, absorption, tissue distribution and biotransformation are influenced significantly by the valence state of the metal.
http://corrosion-doctors.org/Elements-Toxic/Mercury-toxicology.htm
Dear
because of methyl mercury or dimethyl mercury in Organic mercury it is more toxic
Regards
Mercury has 3 forms: (1) elemental mercury, (2) inorganic salts, and (3) organic compounds. Perhaps the most deadly form of mercury is methylmercury (Organic)
Even when literature say metallic Hg is less toxic , you have to be careful with amalgam fillings , because that metallic mercury can be transform to methyl-Hg and move through you body and then oxidase there !!.... and don’t move any more! ( things that you eat , or High Dose of B12 can mobilize metallic mercury , donating the Methyl group to mercury and transforming it to Methyl-B12)... so caution must be for all of them!
Dear Fadel Djamel , this article may be of some interest to your thread and followers.
Metal-toxicity researcher Karen Wetterhahn was a leading light of the field when she died after exposure to a few drops of dimethylmercury, which fell from a pipette onto her latex-gloved hands while she worked in a fume hood. Twenty-five years later, colleagues and scientists reflect on her pioneering work in metal toxicology, her support for early-career scientists and the legacy of improvements to lab safety that followed her death...
https://cen.acs.org/safety/lab-safety/25-years-Karen-Wetterhahn-died-dimethylmercury-poisoning/100/i21
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