Mercuric Cyanide
Mercuric cyanide (also known as Mercury (II) cyanide), Hg(CN)2, is a particularly toxic mercury compound. If ingested, both life-threatening mercury and cyanide poisoning can occur. Hg(CN)2 can enter the body via inhalation, ingestion, or passage through the skin. Inhalation of mercuric cyanide irritates the throat and air passages. Heating or contact of Hg(CN)2 with acid or acid mist releases toxic mercury and cyanide vapors that can cause bronchitis with cough and phlegm and/or lung tissue irritation. Contact with eyes can cause burns and brown stains in the eyes, and long-time exposure can affect the peripheral vision. Contact with skin can cause skin allergy, irritation, and gray skin color.
Chronic exposure to trace amounts of the compound can lead to mercury buildup in the body over time; it may take months or even years for the body to eliminate excess mercury. Overexposure to mercuric cyanide can lead to kidney damage and/or mercury poisoning, leading to 'shakes' (ex: shaky handwriting), irritability, sore gums, increased saliva, metallic taste, loss of appetite, memory loss, personality changes, and brain damage. Exposure to large doses at one time can lead to sudden death.
Mercuric cyanide has not been tested on its ability to cause reproductive damage. Although inorganic mercury compounds (such as Hg(CN)2) have not been shown to be human teratogens, they should be handled with care, as they are known to damage developing embryos and decrease fertility in men and women.
According to one study, two people exhibited symptoms of cyanide poisoning within hours after ingesting mercuric cyanide or mercury oxycyanide, Hg(CN)2•HgO, in suicide attempts. The toxicity of Hg(CN)2 is commonly assumed to arise almost exclusively from mercury poisoning; however, the patient who ingested mercury oxycyanide died after five hours of cyanide poisoning before any mercury poisoning symptoms were observed. The patient who ingested Hg(CN)2 initially showed symptoms of acute cyanide poisoning, which were brought under control, and later showed signs of mercury poisoning before recovering. The degree to which cyanide poisoning occurs is thought to be related to whether cyanide ions are released in the stomach, which depends on factors such as the amount ingested, stomach acidity, and volume of stomach contents. Given that Hg(CN)2 molecules remain undissociated in pure water and in basic solutions, it makes sense that dissociation would increase with increasing acidity. High stomach acidity thus helps cyanide ions to become more bioavailable, increasing the likelihood of cyanide poisoning.
Mercury cyanide was used in two murders in New York in 1898. The perpetrator, Roland B. Molineux, sent poisoned medicines to his victims through the US mail. The first victim, Henry Barnett, died of mercury poisoning 12 days after taking the poison. The second victim, Catherine Adams, died of cyanide poisoning within 30 minutes of taking the poison. As in the suicide cases, the difference between the two cases may be attributed to differences in the acidities of the solutions containing the poison, or to differences in the acidities of the victims' stomachs.
The drug n-acetyl penicillamine has been used to treat mercury poisoning with limited success.
Read more about this topic: Mercury Toxicity, Mechanism, Inorganic Mercury Compounds