Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: pat on 09/01/2003 19:26:49
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The press are having a field day over the discovery of some asylum seekers from North Africa extracting the plant toxin ricin from castor beans.
They are claiming that this constitutes the manufacture of 'weapons of mass destruction'. Sure, I'm not saying that ricin isn't dangerous, nor that large amounts might kill lots of people - but the delivery of adequate amounts to people is the issue. It needs to be injected, or inhaled in largish amounts. It's an assassins tool, not a weapon of mass destruction, surely ?
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Who was the guy who was famously assassinated in London using ricin in the 70's ?
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Markov was the man who ended up on the other end of a deadly umbrella...
For more information on Ricin and how it works, see Martin Westwell's column this month :
http://www.thenakedscientists.com/HTML/articles/article/martinwestwellcolumn8.htm/
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ALL ABOUT RICIN
I thought that I'd gather some complete information together about ricin to dispel a few myths and answer a few emails people have been sending in...
Ricin is a protein and comes from the castor oil plant, Ricinus communis, a native of tropical Africa. Ricin is present throughout the plant but is most concentrated in the seeds which also contain an oil which has been used medicinally in the past, as a laxative, and also in the motor industry, as a lubricant.
The toxic effect of ricin, which can be abolished by cooking the seeds because this destroys the protein, is well known throughout the world. Animals are the most frequent victims but so too are humans who either inadvertently eat the seeds, or are maliciously exposed to the toxin through contamination of their food, as has happened in the cases of some unwanted children in Africa, or are injected with the toxin directly, as in the case of Markov whilst waiting for a bus in London.
An oral dose of 1 milligram (mg or thousandth of a gram) per kilogram bodyweight is fatal, but since most of the protein is destroyed by the digestive tract, much smaller doses as little as 2 millionths of the body weight are required if the toxin is administered by injection, either under the skin or into a vein.
http://www.ansci.cornell.edu/cgi-bin/db2www/plant_indiv.d2w/PHOTO?keynum=73
How does ricin work ?
Ricin consists of two protein sub-units which are linked together chemically. The A subunit, RTA, binds to a piece of cellular machinery called a ribosome where it blocks the cell's ability to make new proteins. The B subunit (RTB) is a lectin which has the ability to bind onto and enter cells, dragging the RTA subunit with it. RTB works by binding onto proteins which have the sugar galactose linked onto them.
Once the ricin binds onto the cell membrane the toxin is pulled in or 'internalised' by the cell and subsequently makes its way to the target ribosomes, where it shuts down protein synthesis and compromises the affected cell.
Symptoms of ricin poisoning
Symptoms take from 2-24 hours to develop following exposure and include abdominal pain, vomiting and (bloody) diarrhoea. It also affects the kidneys and liver, and leads to the death of muscle fibres in the heart, damaging the circulation.
A few days after exposure severe dehydration sets in, indicated by reduced urine production, and the affected individual develops symptoms of thirst, a burning throat, and a headache. There is often a reduction in temperature prior to death and victims show a characteristic shivering.
Administered by injection ricin is twice as toxic as cobra venom, and is probably the most poisonous plant substance known.
How to Treat Ricin Poisoning:
There is no antidote for ricin poisoning so medical intervention is limited to supportive measures including fluids, circulatory support and analgesics, and measures intended to reduce the potential does including charcoal and emetics (agents that induce vomiting). Death normally occurs after a few days, usually due to circulatory collapse or 'hypovolaemic shock'.
Chris
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I heard they were making a movie based on the Markov story. Anyone else hear that?
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fwww.mypixshare.net%2Ffiles%2Fimg%2Fuser_uploads%2Fdisplayimage.php%3Fid%3Dd5x0c6ihjj0g5655171.gif&hash=b7cc40b45bcf12c48b86747c1823e3a1)
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This sheds a new light on the old tradition of administering a spoonful of castor oil weekly to keep you regular.
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It's an assassins tool, not a weapon of mass destruction, surely ?
A weapon of mass destruction is anything a politician wants it to be. In the best cases, it needn't even exist, or be in any way credible. You may recall a certain invasion of Iraq: a pathological liar presented as casus belli the certainty that the regime was able to mobilise WMDs in 45 minutes, then gave not 40 minutes but 3 months notice of his intention to invade. Naturally he was supported unanimously by every other politician: logical thought and actual evidence would be unpatriotic.
A terrorist is anyone who disagrees with a politician and is prepared to say so. Thus a Labour Party member was arrested under the Prevention of Terrorism Act (now entitled, with no hint of irony, the Terrorism Act) for pointing out durng the party conference that either the foreign secretary was lying when he said the invasion was for the purpose of regime change, or the prime minister was lying when he said it wasn't.
"Asylum seeker" is no longer fashionably derogatory. "Islamist" or "insurgent" is the preferred journalese for anyone whose language you do not speak. Asylum seekers eat cheap food; islamists cook up poision.