THE FOLLOWING ARTICLE APPEARED IN THE

JULY 1997 ISSUE

THE POISON SLEUTHS

POISONING BY VANADIUM

-Dr. Anil Aggrawal

"Good morning doctor. Oh, my God, what are you doing today? Oh well, today you are examining a middle aged man. What happened to him?"

"Good morning Tarun. The name of this person is Ramashanker. For some days he is having some respiratory problem. He has difficulty in breathing, persistent cough, sneezing and sore throat. As you can see he is having red eyes too, which in medical parlance is known as conjunctivitis. He is also reporting some weakness, ringing in his ears and headache for a few days. His local doctor prescribed medicines for these ailments but apparently he didn't get any relief. He was then referred to a specialist, who conducted thorough tests on him and then came to the conclusion that he was perhaps exposed to some poison, and that's how this patient came to me."

"And what are your conclusions doctor?"

"Initially Ramashanker was thinking that he is suffering from some natural ailment, but when he heard about himself being possibly exposed to poison, he immediately named his employer as a possible suspect who might be trying to poison him. According to him, his employer was trying to fire him on several occasions but each time the Workers Union intervened and he could not be fired. But his employer was bent upon getting rid of him, and Ramashanker thought that he was probably trying to poison him as a last resort."

"But how can he possibly poison him?"

"The lunch of all the workers is distributed by the employer. It is part of the work conditions. Ramashanker thinks that somebody- most probably his employer- is mixing some poison in his food, perhaps through the help of some goons."

"Do you think he is speaking the truth doctor?"

"Frankly Tarun, I was not convinced by Ramashanker's assertion. But I wanted to examine him in some more detail before coming to any conclusion. When I saw his tongue, I found that it was greenish colored. This set my mind working and I asked where he was working. He answered as I had expected. He was working as a boiler cleaner in a power plant."

"I do not understand what you are referring to. Please explain in some detail."

"Tarun, I think no one is trying to poison him, yet he is suffering from poisoning- poisoning from a very exotic poison."

"Doctor please stop speaking in riddles and tell me what poisoning is he suffering from."

"Tarun, this person surely is suffering from Vanadium toxicity..."

"Vanadium! That doesn't sound like a common poison to me. And how is he suffering from this poisoning when no one gave it to him?"

"Tarun, Boiler cleaning is a highly hazardous profession in which workers are exposed to high levels of Vanadium. Before we proceed further, I think I should tell you a little about Vanadium."

"Yes surely doctor. I would appreciate that. Although I am a good student of chemistry, I know very little about Vanadium, and I would like to know more about it before we discuss its toxicity."

"Tarun, Vanadium is an element having an atomic weight 50.94 and atomic number 23. Its density is 6.11 at 18.10 C. Its melting point is about 18900 C and its boiling point is 33800 C. Elemental Vanadium is a corrosion resistant, hard, steel-grey solid. It was discovered in 1831 by the Swedish chemist Nils Sefstrom. The story of its discovery is very interesting. About 30 years before its actual discovery, in 1801, the Mexican chemist and mineralogist Andres Manuel del Rio was almost on the verge of discovering it, but he missed it by the breadth of thin hair, so to say. In that year he was studying the brown lead ores of Mexico. During his experiments he came across several colored compounds which he initially thought were the compounds of a hitherto unknown metal. He was right. These were the compounds of Vanadium, which are in fact so beautifully colored that today one of their major uses is in coloring pottery and porcelain. He even gave the new element a name "panchromium". "Pan" as you know is a Greek prefix meaning "all". Thus the element meant "all colors", which was quite an apt name because Vanadium compounds come almost in all colors. Later he changed the name to "erytronium" which means "red". But even after all this, del Rio could not proved his discovery scientifically, and thus couldn't get the credit for its discovery. Later the German chemist Friedrich Wohler also made a similar mistake."

"Then how did sefstrom find the element?"

"In 1830s, metallurgy was making its first steps in Sweden and plants were going up in different parts of the country. Quite curiously metallurgists found that iron smelted from some ores was brittle while that from some other ores had great plasticity, i.e. it was less brittle. On investigation it was found that the ores came from different deposits. It was quite obvious that there was some unknown substance, probably a new element, in some ores which was giving rise to this high plasticity of steel. Sefstrom was determined to isolate this new element and after strenuous efforts he was able to do just that. He and another Swedish chemist Jons Jakob Berzelius named this new element Vanadium, after a Swedish Goddess of love, Vanadis!"

Interesting! But why this element should be named after a goddess of love?"

"Berzelius was an established chemist and he was a very imaginative person. He described the story of Vanadium's discovery as an interesting allusion. He construed the earlier scientists such as del Rio and Wohler as prospective lovers who knocked at the door of a nubile young girl, but couldn't get her simply because they were not persistent enough and went away after knocking just once. Sefstrom was persistent enough to knock at the door of this girl continuously till the girl opened the door and thus was able to get that girl. Obviously the allusion of the girl was to this new metal, and of the knocking to the efforts made to extract that metal. Since Berzelius likened the new metal to a young nubile girl, he preferred to name it after the Swedish Goddess of love, Vanadis. It is said that after Sefstrom's success Wohler wrote to a friend,`I was a real ass to have overlooked the new element in the brown lead ore, and Berzelius was quite right when he laughed at me and described, not without irony, how I knocked at the door of Vanadis, so feebly, bashfully and haplessly!'"

"Interesting indeed. How is Vanadium extracted from ores today?"

"Tarun, Vanadium accounts for about 0.2% of earth's crust, which may not sound much but would sound significant when you consider that even this concentration is about 15 times more than that of lead and 2,000 times more than silver. But the world production of this metal is far less than these two metals. The world production of Vanadium was just 3 tons in 1907. It however increased to 18,000 tons in 1971 and 21,000 tons in 1975. The main producers are South Africa, US, erstwhile USSR and Finland. The reason why the production of this metal is far less than the other two metals is that it is fairly evenly spread in the crust unlike the other two metals which often occur in accumulations. Vanadium rarely occurs in accumulations, and ores containing just one percent of Vanadium are regarded as exceptionally rich. Even ores containing a mere 0.1% are taken for industrial processing. There are about 60 Vanadium minerals but mining is restricted to carnatite, which is a source of both uranium and Vanadium and vanadinite. Curiously, the meteorites that hit the earth contain two to three times more Vanadium than the earth's crust. Solar matter is also much richer in this element than our planet is. On earth, coal and oil have high quantities of Vanadium. Some coals may have up to 1% Vanadium, but the average is about 30 mg/kg, which is still quite high. Among the oils the highest concentrations of Vanadium are found in the Middle Eastern and Venezuelan oils which may contain up to 100-1400 mg/kg of Vanadium. Because of this, a significant source of Vanadium is the extraction from the furnace (boiler) ash of power plants which are fueled with residual oils. Because of this very same reason, persons engaged in boiler cleaning business are exposed to exceptionally high levels of Vanadium and they are quite prone to Vanadium toxicity. And this is probably the problem of Ramashanker"

"Oh, I see. Before we go on to its toxicity, can you please tell me how such a toxic metal can possibly be used in any way?"

"Tarun, despite Vanadium being toxic, it finds use in many industries. Its greatest use is in the production of special steels. You may be surprised to know that about 80% of the world production of Vanadium is used for this purpose. A small addition -just fraction of a percent- of Vanadium to steel makes it fine grained, very resilient, very strong and better fit to resist impact and bending. In fact, it has been described as a "vitamin" for steel. Interestingly both words begin with V. There is an interesting story regarding this use..."

"Oh, I am a sucker for good scientific stories. Please tell me this story doctor."

"The motor king Henry Ford is supposed to have said,`But for Vanadium, there would have been no automobile'. In 1905, he was present at a big motor racing event. Quite coincidentally a collision occurred. Ford went to up to the scene of the accident and picked up a fragment of one of the crashed cars. It was a French car and the fragment had belonged to its valve spindle. Ford was struck by its lightness and considerable hardness. Out of curiosity he sent it to a laboratory for analysis. The report came that this unusually steel contained Vanadium. Ford introduced this technology on a much larger scale in his own cars. And thus although this technology was known to the French before, it really came to be used on a mass scale only after Ford came to know about it. Today such important vehicle parts as the engine, valve springs, suspension springs, axles, shafts and gears are manufactured from steel laced with vanadium."

Interesting. What are its other uses?"

"As I said earlier, its salts are beautifully colored. The colors of these salts range from green, yellow, red and black to golden and hence they are used in porcelain and pottery industry to color them. Vanadium pentoxide and certain compounds of vanadium known as metavanadates are important catalysts in inorganic and organic chemical industries. They are used in sulfuric acid and plastic production. But only about 3% of all Vanadium is used as catalysts."

"Does it have any medical use too?"

"Vanadium does not appear to have any medical use. However dental caries incidence in children aged 7-11 years was reduced three times as compared to controls by local application of ammonium vanadate in glycerol. This is however an early Russian study and other workers have not been quite convinced by these results."

"You said Vanadium is toxic. Can we ingest it through food too? And what about other sources of Vanadium?"

"Wide variations occur in Vanadium levels in food. In the potato the reported concentrations range from about 1 mg/kg to 1.5 mg/kg. This could be due to differences in Vanadium concentrations in soil or to the bias of analytical methods or both. In cow's milk Vanadium was found at levels from about 0.2 mg/kg to 10 mg/kg. Meat concentrations are about 1 mg/kg. Vanadium is present in the air too. Its concentrations recorded in rural areas in the United Kingdom and Canada varied from 0.25 to 75 ng/m3. The concentrations in urban areas are higher- 60 to 300 ng/m3. There is marked seasonal variation, the mean for winter months being 6 times higher than for summer months. It has been estimated that about 1 mg of Vanadium could enter the respiratory tract per day if air concentrations are assumed to be about 50 ng/m3. The major sources of atmospheric emission are metallurgical works, followed by oil and coal burning. Fossil fuel combustion is the largest source of air pollution by Vanadium. You may recall that coal and oil are among the richest sources of Vanadium. The concentrations of Vanadium in water depend largely on geographical location and may range from about 0.2 to more than 100 mg/L. Levels of Vanadium in drinking water in India are not known but in the United States the average level has been found to be 4.3 mg/L. However typical values in drinking water appear to be about 1 mg/L. Concentrations in the soil range from about 5 to 140 mg/kg, and may reach high values when the soils are polluted by fly-ash. Then the values may shoot up to 400 mg/kg."

"You said Ramashanker was suffering from Vanadium toxicity and you said that this occurred because he was working as a boiler cleaner. Are their other jobs too in which Vanadium can be absorbed?"

"Tarun, industries where exposure to Vanadium may occur are Vanadium pentoxide production, Vanadium metal production, and production of Vanadium catalyzers. But as I said earlier, the most dangerous profession still is probably boiler cleaning. Very high levels in air may occur in boiler cleaning which may range from 17 to 60 mg/m3."

"Doctor, what happens to Vanadium inside the body. Since it is not a normal constituent of the body, it should not have any use for it?"

"Ingested Vanadium compounds are, in general, poorly absorbed. The absorption of soluble Vanadium compounds is just about 2%, i.e. if someone ingests 100 mg of a soluble Vanadium compound, only about 2 mg of it would be absorbed. Thus Vanadium salts, are very poor candidates for homicidal poison; they are simply not absorbed from the gastrointestinal tract. On the other hand Vanadium is a very important and interesting environmental poison because it is rapidly absorbed from the lungs! Skin is a minor route of absorption in man. Absorbed Vanadium accumulates in mainly in bone, and to some extent in the liver, muscle and kidney. The whole Vanadium content of a normal human weighing about 70 kg has been estimated to be between 17 and 43 mg. Interestingly although Vanadium is toxic, it is an essential element for chicks and rats, and its deficiency may result in their growth reduction and impairment of reproduction!"

"You said that Ramashanker is suffering from Vanadium toxicity. How can you prove it in a court of law, if Ramashanker prefers to sue his employer for poisoning him intentionally?"

"Tarun, his symptoms, especially his respiratory symptoms and his greenish tongue, coupled with the fact that he is working as a boiler cleaner are quite strong proofs in support of my contention. Yet there is an interesting test by which I can prove my theory. In Vanadium toxicity, the cystine content of fingernails is supposed to decrease. Cystine as you know is an amino acid. Thus determination of the cystine content of finger-nails is a useful diagnostic tool during a continuing exposure of Vanadium. I have already done that and I have indeed found the cystine levels in his fingernails to be reduced. Thus I shall have no difficulty in explaining to the court that Ramashanker is indeed suffering from Vanadium toxicity, and nobody is trying to poison him intentionally. Of course under the various industrial laws, he is entitled for compensation, should his toxicity make him an invalid. But I feel he should be shifted to some other work, so that his exposure to Vanadium is minimized and in time he would be alright. I would also be giving him a drug called BAL. It stands for British Anti Lewisite and is useful in the toxicity of several metals. I am sure that in time, he would be completely alright."

"Thank you doctor for letting me know about such an interesting poison. What are you going to tell me next time?"

"Tarun, next time I shall tell you about Methyl Bromide, which as you shall see is a very important poison. "