THE FOLLOWING ARTICLE APPEARED IN THE

JUNE 2000 ISSUE

THE POISON SLEUTHS

DEATH BY FLUORINE

-Dr. Anil Aggrawal

"Good morning doctor. Oh, my God, what are you doing today? You have the dead body of a young man today. What happened to him? Please tell me.”

“Good morning Tarun. The name of this person is Ramlal and he was 26 years old. He was found dead in his room today morning. When the milkman came to deliver the milk in the morning today, Ramlal did not open the door, and he got suspicious. This was especially because Kalu, his neighbor had threatened to kill him several times.”

“Who is Kalu doctor, and why did he want to kill Ramlal?”

“Tarun, Kalu is a 35 year old person, who lives in the neighborhood. Kalu thought that Ramlal used to meet his wife furtively, although all the other neighbors sincerely believed that this was not the case. Many times, they even told Kalu that he was mistaken, but he did not believe anyone. Many a time, Kalu has even threatened to kill Ramlal, if he did not stop meeting his wife. Let me tell you that Kalu works in a chemical factory making all sorts of chemicals. He is a reasonably good chemist and knows a lot about various chemicals.”

“So what happened when the milkman came?”

“Yes, I was telling you about the events occurring in the morning today. When Ramlal did not open the door, milkman enquired from the neighbors if he had gone out for a few days, and he was informed that Ramlal was very much in town. In fact one person told, that he had seen Ramlal with Kalu only the previous night. As Ramlal always got up late, there was no question of his having got up early and going out for a walk or something. Everybody got suspicious. They called the police. When the door was forced open, everyone was stunned to see Ramlal lying dead on his cot. Everyone noticed a faint smell coming from the room, but they could not identify that smell. They said that they had never smelt anything like that.”

“Perhaps Ramlal was not keeping his room tidy and hence the smell”

“It was not that kind of smell. At least that is what has been informed to me by the neighbors.”

“Doctor, how do you think Ramlal died?”

“Tarun, this is a case which even defeated me for several hours. Since he was not admitted to a hospital, I did not have a hospital report to fall back upon. You might have noticed that many times, hospital records, such as initial symptoms etc give away the cause of death. If a poison has been administered to the individual, we can immediately know about that poison from the symptoms encountered. But in this case, there was no hospital report, and I had to rely solely on my postmortem findings. To make matters worse, there were no significant postmortem findings. The only findings which deserve mention are a reddening of his eyes, and of the mucus membranes of his respiratory tract, such as those of nose and windpipe. His lungs were very much congested with blood. His stomach showed lot of alcohol. It appears he had been drinking alcohol before his death.”

“Perhaps he died by consuming too much liquor?”

“I have done his blood alcohol levels. A blood alcohol level of around 600 mg% is necessary to kill a human being. But in his case, the blood level was just about 150 mg%, enough to produce a mild sensation of well-being, but not death. We enquired the neighbor - a person called Shamu - who claims having seem him with Kalu the day before. Shamu told that Kalu came to Ramlal’s house at about 9 pm the previous night. He had a big bag in his hand. Shamu knew it because at that time he was just returning to his house from his evening walk. When Shamu asked what he was doing there, initially Kalu looked nonplussed but very soon, he regained his composure. He told that that he wanted to bury the hatchet with Ramlal, and was going to his house to have a friendship drink. He even opened the bag and showed him a bottle of Rum which he had with him.”

“Then how are you going to find out how he died?”

“Tarun. I had just three abnormal and suspicious looking pieces in the whole story. One that Kalu his neighbor who was his enemy, showed a suspicious behavior the previous night, and two that Kalu works in a chemical factory. Add to this the third factor that the neighbors noticed some strange smell coming out from the house when they opened the door, and my mind immediately turned towards some poisonous gas as the possible killing agent. Still I was in the dark because there are so many gases which can kill a person. I had no way but to perform a chemical test on his lungs, and guess what I found - fluorine! Ramlal has died because of fluorine”

“Come on doctor. We have never heard of a person dying from fluorine. He must have died some other way.”

“Tarun, I am very sure Ramlal died of fluorine. In fact the circumstances which Kalu created were perfect for a killing with fluorine. He first made Ramlal tipsy with alcohol and then released fluorine which he had brought with him in his bag. He had this gas in a pressurized container, which the police has seized from a half opened almirah. Of course they would never have looked for it, had I not told them about it. I went to Ramlal’s house and did some tests on the air in his room. Although much of the fluorine had diffused out of Ramlal’s room, yet I could demonstrate a significant amount of fluorine in his room.”

“Doctor, it appears we are on to some other good of your stories. Please tell me something about fluorine first, so I can follow you better.”

“Tarun, fluorine (F), is the most reactive chemical element, and the lightest member of the halogen elements, or Group VIIa of the periodic table. Its atomic number is 9, atomic weight 18.9984, melting point -219.62° C (-363.32° F), boiling point -188° C (-306° F), and density at 1 atm, and 0° C about 1.696 g/litre. Under ordinary conditions fluorine is a gas a little heavier than air, with a pale yellow colour; inhalation except in very low concentrations is dangerous. Upon cooling, fluorine becomes a yellow liquid. Fluorine occurs combined in the widely distributed mineral fluorite ( calcium fluoride, fluorspar), its chief source, in the minerals cryolite and fluorapatite, and in small amounts in seawater, bones, and teeth. Not a rare element, it makes up about 0.065 percent of the Earth's crust. Only one isotope occurs in nature, stable fluorine-19. Let me tell you that Fluorine is difficult to isolate from its compounds, and in fact it is impossible to free it by chemical means. No other element is powerful enough, as an oxidizing agent, to replace it.”

“Doctor since when do we know about fluorine?”

“Tarun, the French chemist Henri Moissan first isolated fluorine in 1886 by electrolysis of anhydrous hydrogen fluoride (HF), in which potassium hydrogen fluoride (KHF2) had been dissolved to make it conduct a current. Elemental fluorine of high purity is prepared commercially by Moissan's procedure. The elemental gas is used as an oxidizer in rocket fuels and to prepare fluorides. Fluorine, composed of two-atom molecules (F2), is so reactive that it combines with all other elements except helium, neon, and argon to form ionic or covalent fluorides. Its chemical activity can be attributed to its extreme ability to attract electrons (in fact, it is the most electronegative element) and to the small size of its atoms. The oxidation state of -1 is the only one observed in fluorine compounds. Because of the small size of the fluoride ion (F-), it forms many stable complexes with positive ions; for example, hexafluorosilicate(IV) (SiF62-) and hexafluoroaluminate(III) (AlF63-).

One of the principal industrial compounds of fluorine is hydrogen fluoride, obtained by treating fluorite with sulfuric acid. It is employed in the preparation of numerous inorganic and organic fluorine compounds of commercial importance, e.g., sodium aluminum fluoride (Na3AlF6), used as an electrolyte in the electrolytic smelting of aluminum metal; and uranium hexafluoride (UF6), utilized in the gaseous diffusion process of separating uranium-235 from uranium-238 for reactor fuel. A solution of hydrogen fluoride gas in water is called hydrofluoric acid, large quantities of which are consumed in industry for cleaning metals and for polishing, frosting, and etching glass.

Boron trifluoride (BF3) and antimony trifluoride (SbF3), like hydrogen fluoride, are important catalysts for organic reactions; cobalt trifluoride (CoF3) and chlorine trifluoride (ClF3) are useful fluorinating agents; and sulfur hexafluoride (SF6) is used as a gaseous electrical insulator. Sodium fluoride (NaF) is used to treat dental caries and is often added in small amounts to fluoride-deficient water supplies (fluoridation) to reduce tooth decay.

Elemental fluorine, often diluted with nitrogen, reacts with hydrocarbons to form corresponding fluorocarbons in which some or all hydrogen has been replaced by fluorine. The resulting compounds are usually characterized by great stability, chemical inertness, high electrical resistance, and other valuable physical and chemical properties. This fluorination may be accomplished also by treating organic compounds with cobaltic fluoride or by electrolyzing their solutions in anhydrous hydrogen fluoride. Useful plastics with non-sticking qualities, such as polytetrafluoroethylene ([CF2CF2)x]; known by the commercial name Teflon), are readily made from unsaturated fluorocarbons. Organic compounds containing chlorine, bromine, or iodine are fluorinated to produce compounds such as dichlorodifluoromethane (Cl2CF2), the coolant used in most household refrigerators and air conditioners."

“Doctor, what is the color of this gas? And how does it smell?”

“Fluorine is a yellow gas that does not occur free in nature because of its great reactivity. Before World War II it was generated only in gram quantities, but the need for stable fluorocarbons in the atomic energy program stimulated the chemical industry to devise electrolyte cells for the preparation of elemental fluorine. The present availability of the compressed gas in nickel or steel cylinders has led to its use for the preparation of a host of new organic fluorine compounds, many of them of commercial value. The gas can be liquefied at low temperatures. Its odor differs from that of chlorine. It is rather difficult to describe, but it can be compared to that of relatively concentrated ozone. It can be piped through standard steel pipe or copper tubing equipped with Monel metal…”

“Sorry to disturb you doctor, but what is Monel metal?”

“Tarun, fluorine is a very reactive gas, and thus it can only be piped through certain very resistant metals. Monel is any of a group of nickel-copper alloys, first developed in 1905, containing about 66 percent nickel and 31.5 percent copper, with small amounts of iron, manganese, carbon, and silicon. Stronger than pure nickel, Monel alloys are resistant to corrosion by many agents, including fluorine and rapidly flowing seawater, both of which can be very very corrosive to metals. They can be fabricated readily by hot- and cold-working, machining, and welding. Monel is a registered trademark of the International Nickel Company. So I was telling you, how the gas can be piped. Well, it can be piped also through nickel valves with Teflon packing. With metals, fluorine reacts only slowly, except at sufficiently elevated temperatures. Under suitable conditions, it reacts spontaneously with most materials at room temperature except the inert gases, metal fluorides in their highest valence states, and carbon tetrachloride. Under some conditions, fluorine at atmospheric pressure can burn even steel equipment. For reasons unknown, fluorine does not always react with water, but at times the reaction may occur explosively. With the moisture of the air, it forms hydrogen fluoride and, possibly, oxygen fluoride, OF2."

“Doctor, how does fluorine kill a person? Have scientists done some studies on how fluorine kills a man?”

“Tarun, the only studies of the effects of exposure of animals to metered dilutions of fluorine in nitrogen were those made at the University of Rochester by a team led by Stokinger in 1949. They did a number of experiments on various animals, and let me tell you what they found. The gas was uniformly fatal to rabbits, guinea pigs, rats, and mice in exposures ranging from 5 minutes at a concentration of 10,000 parts per million (p.p.m.) to 3 hours at 200 p.p.m. Guinea pigs survived an exposure of 7 hours to 100 p.p.m., but the over-all mortality among the various species was 60 per cent. Respiratory damage, with swelling of the lungs - technically called pulmonary edema-, was the cause of death. More prolonged exposure, up to 35 days, was made to lesser concentrations. Irritation of the eyes and nasal and mouth mucosal lining was noted at concentrations of 5 to 10 p.p.m., and dogs exhibited irrational seizures, many of which were fatal. Moderate to severe lung irritation occurred at all levels down to 3 mg./cu. meter, and rats showed also a high degree of destruction of their testes at 25-mg. level. The tolerated exposure was taken as 1 p.p.m. (1.7 mg./cu. meter),and hydrogen fluoride and fluorine were regarded as independently toxic.

The Rochester group also exposed the skin of the back of anesthetised rabbits for periods of 0.2 to 0.6 sec. at a distance of 1 in. to fluorine under 40 lb. pressure. The briefest exposure led to the appearance of a small area devoid of blood about 1/4 inch in diameter, surrounded by an reddened area. This became a superficial eschar that sloughed off by the fourth day, disclosing normal epidermis. The longer exposures were accompanied by a flash of flame, burning the hair and causing a special type of destruction - technically known as coagulation necrosis - of the burned area and charring of the epidermis. The thermal flash burns resembled those induced by an oxyacetylene flame.”

“Sounds like a really dangerous gas. Doctor, you told me that Kalu worked in a factory from where he might have smuggled a canister of fluorine. Surely if Kalu works in a factory, he himself might be exposed to it. Has the government set up any regulations regarding it?”

“No, to the best of my knowledge, there are no governmental regulations on the allowable concentrations of fluorine. But the American Conference of Governmental Industrial Hygienists (1961) has recommended 0.1 p.p.m. as the threshold limit for fluorine. Apparently if the concentration increases beyond it, there is danger to one’s health.”

“Doctor, now I know reasonably enough about fluorine. Please tell me how Kalu killed Ramlal with Fluorine”

“Tarun, it was a very devilish plan. Kalu stole a canister of fluorine from where he was working. He was working in a chemical factory, and it was not difficult for him to do that. He knew about the killing potential of fluorine as he had studied chemistry upto college level and was reasonably conversant with all the chemicals, and their effects on the human body. He knew that if he released the gas in Ramlal’s house he would recognize the smell and would throw open the doors and windows of his house. So he decided to first lull his senses. For this purpose he came to Ramlal’s house along with a bottle of liquor. Did you notice that Shamu told us he had a big bag with him, and from it he took out a bottle of liquor to show him. I am sure that the canister of fluorine was also in the very same bag, but he did not take it out to show to Shamu. At Ramlal’s house, he said that he wanted friendship. Ramlal was also tired of day-to-day bickerings and he readily agreed for a drink. After two or three pegs, when Ramlal was quite tipsy, Kalu got up on the pretext of going to the bathroom. He furtively opened a nearby almirah, put the canister inside it, and slightly unscrewed its cap, so the gas could leak slowly into the room. After this he went to the bathroom. When he came back, he found Ramlal lying lazily in his bed, with his eyes closed. Kalu took leave of him, and came back to his house. Ramlal closed the door behind him, and came back to his bed to sleep. By this time, enough gas had not come out of the canister to arouse Ramlal’s suspicions. Anyway, Ramlal was drunk, and he was not in a position to recognize the special odor of fluorine. Soon he fell asleep. The concentration of fluorine increased in the house, and killed him in his sleep. Ramu did one mistake in his whole episode. He left the canister in the almirah. He never thought that our investigation can be so thorough. Anyway, this was the only way, he could ensure a gradual build-up of the gas in Ramlal’s house. Come, let us tell the police that Kalu has killed Ramlal, and that he should be caught”

“That is very clever of you doctor. Without your clever deduction it would have been impossible to say how Ramlal died and Kalu may have gone scot-free. What are you going to tell me next time?”

“Tarun, next time, I would tell you about a very interesting poison - Potassium Bromate."