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Ricin

Castor beans

The protein ricin (pronounced rye-sin) is a poison manufactured from the castor bean (Ricinus communis). Its name comes from the seed's resemblance to the tick. Ricin can be extracted from castor beans and is known to have an average lethal dose in humans of 0.2 milligrams (1/5,000th of a gram), though some sources give higher figures [1]. It is considered to be twice as deadly as cobra venom.

Toxicity and manufacture

Ricin is poisonous if inhaled, injected, or ingested, acting as a toxin by the inhibition of protein synthesis. There is no known antidote; only symptomatic and supportive treatment is available. Long term organ damage is likely in survivors. In small doses, such as the typical dose contained in a measure of castor oil, ricin causes digestive tract cramps. Ingested in larger doses, ricin causes severe diarrhea and victims can die of shock. (See abrin).

Although the castor bean plant has long been noted for its toxicity, ricin was first isolated and named in 1888 by Hermann Stillmark. Modern feed-making techniques break down the ricin in castor beans by heating at 140 degrees Celsius for 20 minutes, although some studies suggest that residual toxic effects may linger. Although one seed contains enough ricin to kill an adult human, they may pass harmlessly through the digestive system if swallowed whole. [2]. Typically 2.5–20 raw seeds can kill an adult human; 4 a rabbit, 5 a sheep, 6 an ox, 6 a horse, 7 a pig, 11 a dog, but 80 for cocks and ducks.[3]

Ricin consists of two distinct protein chains (almost 30kDa each) that are linked to each other by disulfide bond:

  • Ricin A is toxic to the cell by interfering with Ribosomes, responsible for protein synthesis
  • Ricin B is important in assisting ricin A's entry into a cell by binding with a cell surface component.

Many plants such as barley have the A chain but not the B chain. Since people do not get sick from eating large amounts of such products, ricin A is of extremely low toxicity if and only if the B chain is not present.

Ricin is easily purified from castor-oil manufacturing waste. The seed-pulp left over from pressing for castor oil contains on average about 5% by weight of ricin. Since 0.2 mg of purified Ricin constitutes a fatal dose, this is a considerable amount of ricin.

As little as one castor bean, about 0.5 grams, may be fatal in a child.

In the United states, a person caught manufacturing or possessing ricin may be sentenced up to 30 years in prison.

Potential medicinal use

Ricin may have therapeutic use in the treatment of cancer. Ricin could be linked to a monoclonal antibody to target malignant cells recognized by the antibody. Genetic modification of ricin is believed to be possible to lessen its toxicity to humans, but not to the cancer cells. A promising approach is also to use the non-toxic B subunit as a vehicle for delivering antigens into cells thus greatly increasing their immunogenicity. Use of ricin as an adjuvant has potential implications for developing mucosal vaccines

Use as a chemical/biological warfare agent

The United States investigated ricin for its military potential during the First World War. At that time it was being considered for use either as a toxic dust or coated bullets and shrapnel. The dust cloud concept could not be adequately developed, and researchers believed the coated bullet/shrapnel concept was unethical. The War ended before it was weaponized.

During the Second World War the United States and Canada undertook studying ricin in cluster bombs. Though there were plans for mass production and several field trials with different bomblet concepts, the end conclusion was that it was no more economical than using phosgene. This conclusion was based on comparison of the final weapons rather than ricin's toxicity (LD50 <30 mg.min.m–3). Ricin was given the military symbol W.

The best-known documented use of ricin as an agent of biological warfare was by the Soviet Union's KGB during the Cold War. In 1978, the Bulgarian dissident Georgi Markov was assassinated by Bulgarian secret police who surreptitiously 'shot' him on a London street with a modified umbrella using compressed gas to fire a tiny pellet contaminated with ricin into his leg. He died in hospital a few days later; the pellet was discovered by chance during an autopsy and the poison linked back to the KGB. Earlier, Soviet dissident Aleksandr Solzhenitsyn also suffered (but survived) ricin-like symptoms after a 1971 encounter with KGB agents (D.M. Thomas, Alexander Solzhenitsyn: A Century in His Life, 368-378).

Despite ricin's extreme toxicity and utility as an agent of chemical/biological warfare, it is extremely difficult to limit the production of the toxin. Under both the 1972 Biological Weapons Convention and the 1997 Chemical Weapons Convention, ricin is listed as a schedule 1 controlled substance. Despite this, more than 1 million metric tonnes of castor beans are processed each year, and approximately 5% of the total is rendered into a waste containing high concentrations of ricin toxin [4].

In August of 2002, US officials asserted that the Islamic militant group Ansar al-Islam tested ricin, along with other chemical and biological agents, in northern Iraq.

To put ricin used as weapon into perspective, it is worth noting that as a biological weapon or chemical weapon, ricin may be considered as not very powerful, if only in comparison with other poisons such as botulinum or anthrax. Hence, a military willing to use biological weapons and having advanced resources would rather use either of the latter instead. Ricin is easy to produce, but is not as practical nor likely to cause as high casualities as other agents. Ricin denatures (ie, the protein changes structure and becomes less dangerous) much more readily than anthrax spores, which may remain lethal for decades. (Jan van Aken, an expert on biological weapons explained in an interview with the German magazine Der Spiegel that he judges it rather reassuring that Al Qaeda experimented with ricin as it suggests their inability to produce botulin or anthrax.)

Pure ricin could be dispersed through the air, however it would tend to be oxidized and rendered harmless by ozone, nitrogen oxides, and other pollutants in a matter of hours. Since it acts as an enzyme, catalyzing destruction of ribosomes, even a single oxidation is likely to render the ricin molecule harmless. Presumably it could be sealed inside some sort of dust particle that would dissolve in water, but this would be difficult.

The major reason it is dangerous is that there is no specific antidote, and that it is very easy to obtain (the castor bean plant is a common ornamental, and can be grown at home without any special care). Ricin is actually several orders of magnitude less toxic than botulinum or tetanus toxins, but those are more difficult to obtain.

Ricin patent

"Preparation of Toxic Ricin",
patent application.

The process for creating ricin is well-known, in part because a patent was granted for it in 1952. The inventors named in US Patent 3,060,165 (granted October 23, 1962) "Preparation of Toxic Ricin", assigned to the U.S. Secretary of the Army, are Harry L. Craig, O.H. Alderks, Alsoph H. Corwin, Sally H. Dieke, and Charlotte Karel.

The patent was removed from the United States Patent and Trademark Office (USPTO) database sometime in 2004, but is still available online through international patent databases.

Ricin extraction process

The extraction of ricin from castor beans is very similar to the prepartion of soy protein isolates. Modern extraction plants might use membrane filtration to make highly purified ricin isolates

Ricin is initially extracted from defatted castor beans by aquous extraction at pH 3.8 to yield a leachate containing solubilized ricin. The leachate is filtered to remove insoluble matter and the crude ricin then precipitated by the addition of a 12% solution of sodium sulfate with a pH of 7.0-8.0. After precipitation, the crude ricin cake is washed with a 16.7% solution of sodium sulfate to remove extranious nitrogenous substances. The precipitated ricin may be reextracted once to further purify it.

The final ricin precipitate is dried and then purified by floatation in carbon tetrachloride. An aerosol powder may be prepared by spray drying or air grinding the purified ricin using cold air.

Ricin-related arrests in Britain in 2003

It was widely reported in the media that traces of ricin were detected by British police in a flat in Wood Green, North London after a raid on a suspected ring of terrorists on 5 January 2003. Media reports stated that a group was suspected of intending to use the poison in an attack on the London Underground. However at the trial of Kamel Bourgass in 2005 it became apparent that within a few days of the raid the leader of the Biological Weapon Identification Group at the Porton Down Defence Science and Technology Laboratory had concluded that ricin was not present at Wood Green [5] [6]. Some acetone, 22 castor beans, and poor recipes for ricin and other poisons copied from the Internet were found. It appears that an individual conducting amateur research on poisons was found in this raid.

A little later several arrests were made in France and a bottle of something that tested positive for ricin was found. Further analysis identified the material as ground wheat germ. The analytic confusion was caused by the similarity of many plant proteins to one of the ricin components, which suggests that higher quality (better specificity and sensitivity) analytic tests for ricin are needed.

Six more suspects were arrested in Bournemouth in England in connection with the investigation into the alleged ricin incident in London. They were not convicted of any poisons related crime.

Three more suspects were arrested in Manchester in England in connection with the investigation of the alleged ricin found in London, following a raid carried out pursuant to an investigation into immigration issues. A Special Branch policeman, DC Stephen Oake, was fatally stabbed during the arrests, and three other officers were also injured, one seriously.

On January 20, 2003 Finsbury Park mosque was raided by police, apparently as part of the investigation into the alleged discovery of ricin in Wood Green. A number of men who were apparently living at the mosque were arrested.

On February 5, 2003, U.S. Secretary of State Colin Powell presented those arrested as the "UK Poison Cell" of a global terrorist network in making the case for military intervention in Iraq to the UN Security Council [7].

In April 2005 31-year-old Kamel Bourgass was jailed for 17 years after being convicted of conspiracy to commit a public nuisance "by the use of poisons and explosives to cause disruption, fear or injury". He was also jailed for life following a conviction for murdering the Special Branch policeman who went to arrest him. All others accused in connection with the Wood Green flat were acquitted on all counts.

Ricin in Washington, D.C.

Ricin was detected in the mail at the White House in Washington, D.C. in November of 2003. The letter containing it was intercepted at a mail handling facility off the grounds of the White House, and it never reached its intended destination. The letter contained a fine powdery substance that later tested positive for ricin. Investigators said it was low potency and was not considered a health risk. This information was not made public until February 3, 2004, when preliminary tests showed the presence of ricin in an office mailroom of U.S. Senate Majority Leader Bill Frist's office. There were no signs that anyone who was near the contaminated area developed any medical problems. Several Senate office buildings were closed as a precaution.

Ricin in popular culture

Ricin was the poison used in the Agatha Christie Tommy and Tuppence whodunnit The House of Lurking Death in a 1929 collection of short stories called Partners in Crime.

Ricin was used as the poison of choice of the murderer in the 1962 comedy film Kill or Cure.

Ricin was mentioned in the "call me the prankster" comic at toothpaste for dinner

The Penn and Teller book How To Play With Your Food (ISBN 0679743111) includes a "gimmicks envelope" of small objects related to the tricks inside the book. One of these is a sticker reading "With all-natural ricin!". The book explains that ricin is a poison.


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The book explains that ricin is a poison. After the choice, practically all these unique features have been removed from the updated designs in favor of a more simplified monolithic structure, putting into doubt whether or not the public would have chosen this new design had it been the one originally presented. One of these is a sticker reading "With all-natural ricin!". Some critics have noted that the initial choice for this design of the Freedom Tower was based on the elaborate latticework, the vertical gardens, and an otherwise unique shape after all the other design contenders were eliminated for being too unoriginal. The Penn and Teller book How To Play With Your Food (ISBN 0679743111) includes a "gimmicks envelope" of small objects related to the tricks inside the book. As of the latest design, there appears to be no attempt to integrate either concept into the tower. Ricin was mentioned in the "call me the prankster" comic at toothpaste for dinner. In the original Memory Foundations proposal, the Freedom Tower was to include a vertical garden memorial known as "Gardens of the World." This idea appeared to have been rejected on the basis of a lack of rentable value, and the gardens were replaced in the intermediate design by the wind turbines and latticework that proved to be less popular.

Ricin was used as the poison of choice of the murderer in the 1962 comedy film Kill or Cure. It was most widely criticized for its immense latticework which many observed to look rather skeletal. Ricin was the poison used in the Agatha Christie Tommy and Tuppence whodunnit The House of Lurking Death in a 1929 collection of short stories called Partners in Crime. That intermediate design was probably the least popular of the three designs and appeared to be a predictable shortcoming that should have been foreseeable from such a compromise between diametrically opposed visions for the trade center site. Several Senate office buildings were closed as a precaution. The latticework concept was actually a compromise between the Memory Foundations architect Liebeskind and Childs, who is largely responsible for the final redesign. There were no signs that anyone who was near the contaminated area developed any medical problems. Before the empty frame of latticework entered the picture, an earlier design of the site, called Memory Foundations, was fairly well received in public opinion.

Senate Majority Leader Bill Frist's office. Some believe that the businessman Donald Trump has planned a reconstruction of the twin towers on another place in New York City. This information was not made public until February 3, 2004, when preliminary tests showed the presence of ricin in an office mailroom of U.S. Many of them believe the absence of the iconic Twin Towers creates an ongoing emotional wound that can only be healed by rebuilding the towers as they looked before, as tall or taller. Investigators said it was low potency and was not considered a health risk. These critics saw replacing two towers with a single, shorter tower would be inappropriately humbling and contrary to the proud nature of New York and the United States, even as a symbolic retreat in the face of terrorism. The letter contained a fine powdery substance that later tested positive for ricin. Other Freedom Tower opponents saw the previously-proposed latticework and antenna on top of the tower to be a mask of the reality that the tower's inhabited stories were to have been fewer than the Twin Towers, and in this way would therefore have been shorter than its predecessors.

The letter containing it was intercepted at a mail handling facility off the grounds of the White House, and it never reached its intended destination. There have also been accusations of corruption on the part of New York Governor George Pataki, using his influence to get the winning architect's bid picked as a personal favor for a close friend [4]. in November of 2003. Additionally, some architects contend that a taller building should have been considered, suggesting that for reasons of cost and engineering, taller buildings may actually be safer. Ricin was detected in the mail at the White House in Washington, D.C. The redesigned tower is set to have 82 floors, more than the initial limit, but still far fewer than various comparable towers (even the much shorter Empire State Building has 102). All others accused in connection with the Wood Green flat were acquitted on all counts. The floor limit was imposed by Silverstein, who expressed concern that higher floors would be a liability in a major accident or terrorist attack.

He was also jailed for life following a conviction for murdering the Special Branch policeman who went to arrest him. The design of the Freedom Tower has generated some controversy due to the limited number of floors (a maximum of 70) that were designated for office space and other amenities. In April 2005 31-year-old Kamel Bourgass was jailed for 17 years after being convicted of conspiracy to commit a public nuisance "by the use of poisons and explosives to cause disruption, fear or injury". Some of the tenants of the World Trade Center are expected to return to the site in the Freedom Tower, including a new Windows on the World, which was formerly on the 106th floor of One World Trade Center. Secretary of State Colin Powell presented those arrested as the "UK Poison Cell" of a global terrorist network in making the case for military intervention in Iraq to the UN Security Council [7]. The master planner of the World Trade Center site is architect Daniel Libeskind of Studio Daniel Libeskind, although David Childs of Skidmore, Owings and Merrill, an architect hired by Silverstein, has largely supplanted Libeskind as architect of the Freedom Tower itself. On February 5, 2003, U.S. The Port Authority plans to occupy at least one-third of the office space, but no private-sector tenants have yet been found.

A number of men who were apparently living at the mosque were arrested. The Port Authority estimates the Freedom Tower to cost US$1.5 to 2 billion alone, or about $675/ft² ($7300/m²). On January 20, 2003 Finsbury Park mosque was raided by police, apparently as part of the investigation into the alleged discovery of ricin in Wood Green. However, the Port Authority of New York and New Jersey owns the 16 acre (65 000 m²) site the tower occupies. A Special Branch policeman, DC Stephen Oake, was fatally stabbed during the arrests, and three other officers were also injured, one seriously. Larry Silverstein of Silverstein Properties, the leaseholder and developer of the complex, is the probable owner of the Freedom Tower when completed. Three more suspects were arrested in Manchester in England in connection with the investigation of the alleged ricin found in London, following a raid carried out pursuant to an investigation into immigration issues. The height of the Freedom Tower will probably not be increased before completion, due to the symbolism of having an exact height of 1,776 feet (541 m).

They were not convicted of any poisons related crime. Emaar, the builders of the Burj Dubai tower, are keeping the final height of their building secret, but speculation is that it will surpass all existing structures at a height of over 2,300 feet (700 m) when it is finished in 2008, two years before the Freedom Tower. Six more suspects were arrested in Bournemouth in England in connection with the investigation into the alleged ricin incident in London. If the spire and antenna height (the criteria of the Council on Tall Buildings and Urban Habitat) are included, the Freedom Tower might, when completed, qualify as the tallest office building in the world, if no other rival towers are completed first. The analytic confusion was caused by the similarity of many plant proteins to one of the ricin components, which suggests that higher quality (better specificity and sensitivity) analytic tests for ricin are needed. Union Square Phase 7 and the Shanghai World Financial Center will have roofs and floors higher than Freedom Tower's highest roofs and floors. Further analysis identified the material as ground wheat germ. The Sears Tower, Taipei 101, and other buildings currently have occupied floors higher than the Freedom Tower.

A little later several arrests were made in France and a bottle of something that tested positive for ricin was found. Though not occupied by office space, the Freedom Tower's observation deck is set to be higher, at about 1,362 feet (415 m). It appears that an individual conducting amateur research on poisons was found in this raid. The World Trade Center's North Tower featured an occupied floor at 1355 feet (413 m). Some acetone, 22 castor beans, and poor recipes for ricin and other poisons copied from the Internet were found. It is unique, yet it subtly recalls, in the sky, the tragedy that has happened here." [3]. However at the trial of Kamel Bourgass in 2005 it became apparent that within a few days of the raid the leader of the Biological Weapon Identification Group at the Porton Down Defence Science and Technology Laboratory had concluded that ricin was not present at Wood Green [5] [6]. The building is simpler, architecturally.

Media reports stated that a group was suspected of intending to use the poison in an attack on the London Underground. "It is a rare moment when new is better," said Design Partner David Childs, "I feel better about this than the original. It was widely reported in the media that traces of ricin were detected by British police in a flat in Wood Green, North London after a raid on a suspected ring of terrorists on 5 January 2003. The new redesign much more closely resembles the character of the previous towers than did the original plans. An aerosol powder may be prepared by spray drying or air grinding the purified ricin using cold air. Above the first 150 to 200 feet (50 to 60 m), the redesign may be as much a result of popular opinion and dissatisfaction in New York City with the previous design, or perhaps the growing popularity of the Twin Towers 2 movement, as with the concerns of safety. The final ricin precipitate is dried and then purified by floatation in carbon tetrachloride. Upon the redesign, announced and revealed on June 29, 2005, the upper building design did actually change, and significantly.

The precipitated ricin may be reextracted once to further purify it. As of May 2005, no structural steel had been ordered. After precipitation, the crude ricin cake is washed with a 16.7% solution of sodium sulfate to remove extranious nitrogenous substances. [2] The redesign is said to entail a smaller ground footprint, and it is not known if this means office space in the building will be reduced, or upper floors will be made larger or more numerous to compensate. The leachate is filtered to remove insoluble matter and the crude ricin then precipitated by the addition of a 12% solution of sodium sulfate with a pH of 7.0-8.0. "The building itself, except for the first 150 to 200 vertical feet (46–60 m), will be the same," said Port Authority Vice President Charles Gargano. Ricin is initially extracted from defatted castor beans by aquous extraction at pH 3.8 to yield a leachate containing solubilized ricin. In May 2005, it was announced that a redesign was being done to provide for security from ground level bombs.

Modern extraction plants might use membrane filtration to make highly purified ricin isolates. People involved in the rebuilding effort say that the revisions that need to be made to the site's most prominent feature, the Freedom Tower, could delay the start of construction from several months to a year." [1]. The extraction of ricin from castor beans is very similar to the prepartion of soy protein isolates. Security concerns outlined in April 2005 by the New York Police Department "have set off a serious reassessment of plans for the World Trade Center site. The patent was removed from the United States Patent and Trademark Office (USPTO) database sometime in 2004, but is still available online through international patent databases. New York City is a suitable place to set such a light pointing towards the sky without complaints of light pollution by astronomers, as the night sky in locations near New York City is already far too bright for serious astronomical observations. Dieke, and Charlotte Karel. Also atop the spire will be an intense beam of light that will be lit at night and will likely be visible over a thousand feet (300 m) into the air above the tower.

Corwin, Sally H. On top of the spire, the antenna may, pending design finalization, be the new broadcasting system to various New York television channels and radio stations, replacing the antenna on top of the North Tower of the former World Trade Center complex. Alderks, Alsoph H. Although the roof area of any tower is comparatively limited, the building will implement a greywater recycling scheme involving rainwater collection. Craig, O.H. This will benefit internal daylight propagation; however, at this stage it is unclear how the corresponding issue of solar heat gain will be addressed. Secretary of the Army, are Harry L. "Ultra-clear" glass, as opposed to reflective or tinted glass, is proposed for the fenestration generally.

The inventors named in US Patent 3,060,165 (granted October 23, 1962) "Preparation of Toxic Ricin", assigned to the U.S. The windows on the side of the building facing in this direction will be equipped with specially tempered blast-resistant plastic, which will look nearly exactly the same as the glass used in the other sides of the building. The process for creating ricin is well-known, in part because a patent was granted for it in 1952. At its closest point, West Street will be 65 feet (20 m) away. Ricin is actually several orders of magnitude less toxic than botulinum or tetanus toxins, but those are more difficult to obtain. The building will no longer be 25 feet (7.6 m) away from West Street—with the redesign and smaller base (the same width and length now as each of the previous towers), the Freedom Tower will average 90 feet (27 m) away from the street. The major reason it is dangerous is that there is no specific antidote, and that it is very easy to obtain (the castor bean plant is a common ornamental, and can be grown at home without any special care). Other new safety features will include 3 foot (90 cm) thick walls for all stairwells, elevator shafts, risers, and sprinkler systems; extremely wide "emergency stairs"; a dedicated set of stairwells exclusively for the use of firefighters; and biological and chemical filters throughout its ventilation system.

Presumably it could be sealed inside some sort of dust particle that would dissolve in water, but this would be difficult. Interlocking reflective sheets of these materials along the facade will illuminate in turn as the sun moves across the sky above it. Since it acts as an enzyme, catalyzing destruction of ribosomes, even a single oxidation is likely to render the ricin molecule harmless. The exterior of this base will be encased in reflective sheet metal cladding, likely stainless steel and titanium. Pure ricin could be dispersed through the air, however it would tend to be oxidized and rendered harmless by ozone, nitrogen oxides, and other pollutants in a matter of hours. The next 120 feet (37 m) immediately upward will also lack windows, containing only mechanical floors to fill out the massive cubic base of the building. (Jan van Aken, an expert on biological weapons explained in an interview with the German magazine Der Spiegel that he judges it rather reassuring that Al Qaeda experimented with ricin as it suggests their inability to produce botulin or anthrax.). However, owing to security concerns, the first 30 feet (9 m) up will now lack windows and will rely instead on artificial lighting and openings from 30 to 80 feet (9 to 24 m) high to illuminate the area.

Ricin denatures (ie, the protein changes structure and becomes less dangerous) much more readily than anthrax spores, which may remain lethal for decades. Like the World Trade Center, there will be a large public lobby, with 80 foot (24 m) ceilings, and a restaurant. Ricin is easy to produce, but is not as practical nor likely to cause as high casualities as other agents. This will be higher than the destroyed Twin Towers observation deck, and also slightly higher than the observation Skydeck of the Sears Tower in Chicago. Hence, a military willing to use biological weapons and having advanced resources would rather use either of the latter instead. Instead of 1100 feet (335 m), the new deck will allow views from 1362 feet (415 m), the ceiling height of the previous Tower Two. To put ricin used as weapon into perspective, it is worth noting that as a biological weapon or chemical weapon, ricin may be considered as not very powerful, if only in comparison with other poisons such as botulinum or anthrax. Because there will no longer be a frame of latticework above the habitable space, the observation deck will now be higher than the previous design.

In August of 2002, US officials asserted that the Islamic militant group Ansar al-Islam tested ricin, along with other chemical and biological agents, in northern Iraq. The turbines were expected to generate 20% of the building's power. Despite this, more than 1 million metric tonnes of castor beans are processed each year, and approximately 5% of the total is rendered into a waste containing high concentrations of ricin toxin [4]. The latticework would have constituted nearly 30% of the building's height. Under both the 1972 Biological Weapons Convention and the 1997 Chemical Weapons Convention, ricin is listed as a schedule 1 controlled substance. Wind turbines are generally not suited for urban environments because of turbulence created by other nearby buildings; however, the singular height of the proposed tower would have presented a unique opportunity in this context. Despite ricin's extreme toxicity and utility as an agent of chemical/biological warfare, it is extremely difficult to limit the production of the toxin. The Freedom Tower will not have the "skeletal frame" of latticework and wind turbines: these have been abandoned.

Thomas, Alexander Solzhenitsyn: A Century in His Life, 368-378). There will now be a central spire drawing from precedents such as the Empire State Building and the Chrysler Building rather than an off-center spire intended to echo the Statue of Liberty. Earlier, Soviet dissident Aleksandr Solzhenitsyn also suffered (but survived) ricin-like symptoms after a 1971 encounter with KGB agents (D.M. The Freedom Tower will now consist of simple symmetries and a more traditional design intended to bear comparison with selected elements of the existing New York skyline. He died in hospital a few days later; the pellet was discovered by chance during an autopsy and the poison linked back to the KGB. Many remaining vestiges of the concepts drawn from the 2002 competition have been discarded. In 1978, the Bulgarian dissident Georgi Markov was assassinated by Bulgarian secret police who surreptitiously 'shot' him on a London street with a modified umbrella using compressed gas to fire a tiny pellet contaminated with ricin into his leg. .

The best-known documented use of ricin as an agent of biological warfare was by the Soviet Union's KGB during the Cold War. The building is projected to be ready for occupancy in 2010. Ricin was given the military symbol W. It is projected that steel for the building will be visible above ground in 2007, with a topping out in 2009. This conclusion was based on comparison of the final weapons rather than ricin's toxicity (LD50 <30 mg.min.m–3). Construction on below-grade utility relocations, footings, and foundations for the Freedom Tower is scheduled to begin in the first quarter of 2006, four and a half years after the World Trade Center's destruction and three and a half years after The Pentagon was completely reconstructed. Though there were plans for mass production and several field trials with different bomblet concepts, the end conclusion was that it was no more economical than using phosgene. The walls at the base are offset 45 degrees from the walls of the highest floor with interlocking triangle facades.

During the Second World War the United States and Canada undertook studying ricin in cluster bombs. Depending on which angle the building is viewed from, the Freedom Tower is designed to appear as either a rectangular shape like both of the previous towers, or as a massive obelisk design. The War ended before it was weaponized. However a project for a tower in Chicago, Fordham Spire, is expected to be taller and constructed as early as 2009. The dust cloud concept could not be adequately developed, and researchers believed the coated bullet/shrapnel concept was unethical. The height of the Freedom Tower is intended to surpass the Sears Tower to become the tallest building in the United States, and to be among the tallest buildings in the world when completed. At that time it was being considered for use either as a toxic dust or coated bullets and shrapnel. The height to the top of the spire is set to be 1776 feet (541 m), symbolizing the year 1776, when the United States issued its Declaration of Independence.

The United States investigated ricin for its military potential during the First World War. The tower will be located in the northwest corner of the 16 acre (65,000 m²) World Trade Center site, bounded by Vesey Street, West Street, Washington Street and Fulton Street in Lower Manhattan, New York City. Use of ricin as an adjuvant has potential implications for developing mucosal vaccines. A revised design for the tower was formally unveiled on June 29, 2005, to satisfy security issues raised by the New York City Police Department in April 2005. A promising approach is also to use the non-toxic B subunit as a vehicle for delivering antigens into cells thus greatly increasing their immunogenicity. The Freedom Tower is the name given to the planned centerpiece building of the new World Trade Center complex in New York City, whose predecessors were destroyed in the attacks of September 11, 2001. Genetic modification of ricin is believed to be possible to lessen its toxicity to humans, but not to the cancer cells.

Ricin could be linked to a monoclonal antibody to target malignant cells recognized by the antibody. Ricin may have therapeutic use in the treatment of cancer. In the United states, a person caught manufacturing or possessing ricin may be sentenced up to 30 years in prison. As little as one castor bean, about 0.5 grams, may be fatal in a child.

Since 0.2 mg of purified Ricin constitutes a fatal dose, this is a considerable amount of ricin. The seed-pulp left over from pressing for castor oil contains on average about 5% by weight of ricin. Ricin is easily purified from castor-oil manufacturing waste. Since people do not get sick from eating large amounts of such products, ricin A is of extremely low toxicity if and only if the B chain is not present..

Many plants such as barley have the A chain but not the B chain. Ricin consists of two distinct protein chains (almost 30kDa each) that are linked to each other by disulfide bond:. Typically 2.5–20 raw seeds can kill an adult human; 4 a rabbit, 5 a sheep, 6 an ox, 6 a horse, 7 a pig, 11 a dog, but 80 for cocks and ducks.[3]. [2].

Although one seed contains enough ricin to kill an adult human, they may pass harmlessly through the digestive system if swallowed whole. Modern feed-making techniques break down the ricin in castor beans by heating at 140 degrees Celsius for 20 minutes, although some studies suggest that residual toxic effects may linger. Although the castor bean plant has long been noted for its toxicity, ricin was first isolated and named in 1888 by Hermann Stillmark. (See abrin).

Ingested in larger doses, ricin causes severe diarrhea and victims can die of shock. In small doses, such as the typical dose contained in a measure of castor oil, ricin causes digestive tract cramps. Long term organ damage is likely in survivors. There is no known antidote; only symptomatic and supportive treatment is available.

Ricin is poisonous if inhaled, injected, or ingested, acting as a toxin by the inhibition of protein synthesis. . It is considered to be twice as deadly as cobra venom. Ricin can be extracted from castor beans and is known to have an average lethal dose in humans of 0.2 milligrams (1/5,000th of a gram), though some sources give higher figures [1].

Its name comes from the seed's resemblance to the tick. The protein ricin (pronounced rye-sin) is a poison manufactured from the castor bean (Ricinus communis). Ricin B is important in assisting ricin A's entry into a cell by binding with a cell surface component. Ricin A is toxic to the cell by interfering with Ribosomes, responsible for protein synthesis.

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