Potassium cyanide lethality

When comparing the available acute lethal toxicity information for cyanide compounds, it was concluded that, for oral exposure, the molar lethal toxicities of hydrogen cyanide, sodium cyanide, and potassium cyanide are similar. Rabbits appeared to be more susceptible to the lethal toxicity of these three compounds than rats (Ballantyne 1988). 

Cardio = cardiovascular d = day(s) F = female HCN = hydrogen cyanide KCN = potassium cyanide LD50 = lethal dose, 50% kill LOAEL = lowest-observed- adverse-effect level M = male min = minutes NaCN = sodium cyanide NOAEL = no-observed-adverse-effect level NS = not specified Resp = respiratory... 

Information regarding the rapid lethal effects following oral intake of cyanide in humans indicates that cyanide is rapidly absorbed from the gastrointestinal tract. In a case study, an 80-kg male ingested an estimated 15-25 mg CNVkg as potassium cyanide in a suicide attempt (Liebowitz and Schwartz 1948). 

Excessive alcohol intake can also lead to achlorhydria and it is said that the resistance for cyanide poisoning of the Russian mystic, Rasputin, was attributable to that effect. The great amount of vodka that he consumed led to achlorhydria and thus the ingested potassium cyanide did not liberate lethal hydrocyanic gas, nor was the potassium salt absorbed through the stomach walls. 

Nitrile groups can be introduced into molecules by reacting potassium cyanide with alkyl halides. The organic nitrile group has quite different properties associated with lethal inorganic cyanide Laetrile, for example, is extracted from apricot kernels, and was once developed as an anticancer drug. It was later proposed that the name be spelt liar-trial since the results of the clinical trials on laetrile turned out to have been falsified ... 

Why did cyanide not kill Rasputin immediately It has been suggested that he had a deficiency in his stomach acid, a condition known as achlorhydric gastritis, which might have decreased the production of hydrogen cyanide from the potassium cyanide. There is no evidence for this, however, and it has been disputed the potassium cyanide should still have killed him. The cyanide had been taken with food and wine, which would have delayed the absorption and therefore slowed down the lethal effects. 

A more likely explanation for Rasputin not having been killed by the cyanide was not any superhuman power but that the potassium cyanide may have been allowed to get damp and had degraded into relatively harmless products. There have been other well-documented cases where what should have been lethal doses have been taken without fatal consequences. A combination of food in the stomach and degraded cyanide salts would be enough to account for this. 

Cyanide comes in many forms and not aU are equally poisonous. The most potent and most likely to be lethal is hydrogen cyanide, also known as prussic acid when in solution in water. This is a volatile liquid but the gas can be generated by the action of an acid on cyanide salts (for example, a mixture of potassium cyanide and sulphuric acid). The Nazis generated the hydrogen cyanide for the gas chambers in places like... 

How do scientists, and toxicologists in particular, assess the risk from chemicals and what does their assessment mean Sometimes we can assess the risk of a particular activity from past experience and knowledge. With poisoning cases we know that if someone eats or drinks more than a particular amount of potassium cyanide or Weedol (paraquat) they are likely to die. Hence the risk in an individual poisoning case can be estimated from the known lethal dose and the amount that the victim has eaten, drunk, or inhaled. 

Lambert, R.J., Kindler, B.L., Schaeffer, D.J. (1998). The efficacy of superactivated charcoal in treating rats exposed to a lethal oral dose of potassium cyanide. Ann. Emerg. Med. 17(6) 595-8. 

Caution. All the reagents used and the product are toxic. White phosphorus must be kept under water. It ignites on contact with air the fumes generated are irritating and extremely poisonous. Contact of white phosphorus with the skin causes severe burns. Absorption in any form may be lethal. Even small amounts of potassium cyanide are lethal. For [iS]-crown-6 oral) an LD 50 of 705 mg kg is reported. Crown ethers are skin and eye irritants. All used and emptied equipment is immediately rinsed with a dilute solution of bromine in methanol under a well-ventilated hood. 

Cyanide toxicity varies with the animal species, type of cyanide compound, route of uptake, metabolic state, and other factors. The LD50 for cyanide has been ported in various species. Potassium cyanide, if injected, has a 24h LD50 of 6.7-7.9mgkg in mice. The lethal dose of potassium cyanide infused at a rate 0.1 mg kg min is 2.4 mg kg in dogs breathing room air. When hydrogen cyanide is inhaled by mice,... 

The lethal dose of potassium cyanide (KCN) taken orally is 1.6 mg/kg of body weight. Calculate the lethal dose of potassium cyanide taken orally by a 175-lb person. 

A classical example of how bonds are formed refers to potassium hexa-cyanoferrate(n) [K4Fe(CN)6], made by mixing colourless potassium and ferrous cyanides together to form a brownish-yellow coloured product which lacks the lethal poisonous properties of potassium cyanide. A century ago, Werner explained many such phenomena by his principles that ... 

Estler, C.J., Metabolic alterations in the brain during the course of non-lethal potassium cyanide poisoning and the influence of cyanide antagonists, Naunyn Schmeidebergs Arch. Pharmacol., 51, 413 32, 1965. 

Table 6. Comparative acute lethal toxicity of aqueous solutions of hydrogen, sodium and potassium cyanides...

Estimates of toxicity based on accidental and deliberate poisoning in humans indicates that NaCN has a lethal potential of around 2-3 mg kg 1 and KCN at 3-5 mg kg 1 (Ballantyne, 1987b). Ingestion of alkaline CN salts by humans (calcium, sodium and potassium cyanides) may cause symptomatology which is life-threatening in 30 to 60 min (Hall and Rumack, 1998). Rapid progression to coma, seizures, arrhythmias, intractable hypotension and apnoea may occur, and death is common. 

The lethal doses of the various very toxic compounds can vary over a wide range the LD50 value of the well-known Seveso poison 2,3,7,8-tetrachloro-di-benzo-dioxin (TCDD) indicates higher toxicity than potassium cyanide by a factor of 10 000, but it is less toxic than botulinus toxin by nearly the same factor. 

The table shows that potassium cyanide has about the same lethal dose as another infamous poison, stiychnine. Strychnine is also popular in detective stories, which may be caused by the fact that the action, although quite different from that of cyanide, is also very rapid and easy to recognize. Another important point in these stories is that strychnine is one of the most bitter substances known, which is important for the stories as it creates an opportunity for the writer to dwell on the question of how this characteristic taste was hidden from the victim. 

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