THE FOLLOWING ARTICLE APPEARED IN THE

APRIL 1999 ISSUE

THE POISON SLEUTHS

DEATH BY ARSINE GAS

-Dr. Anil Aggrawal

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

"Good morning Tarun. The name of this middle aged man is Radhey. He used to work in a factory, where they used to make soldering flux. He was working in his factory five days ago, when at about 2 pm, suddenly he started having nausea, headache, vomiting and diarrhea. He had taken lunch only a few minutes before so naturally everybody started thinking that he had had food poisoning. His illness soon became worse. He started complaining of intense headache and pain in the loins. He passed urine after sometime, and everybody was alarmed to see that it was very dark. He was taken to the hospital, where the doctors were unable to diagnose his illness. However the history of having taken his meals only a few minutes before, and the non-specific symptoms prompted some doctor to write "undiagnosed poisoning" on the hospital case sheet."

"So it was a case of poisoning? Was somebody else was poisoned too?"

"No, nobody else was poisoned - of course presuming that Radhey died of poisoning. Only Radhey showed these peculiar symptoms. The tentative diagnosis of "undiagnosed poisoning" flared up everybody's tempers, especially those of Radhey's relatives. They thought that somebody had surreptitiously mixed poison in his food. And all suspicion fell on another man Suleiman."

"Why on Suleiman doctor?"

"Because and Radhey apparently did not have good relations. They did not even talk to each other. Nobody knows how their fight started, but it is for sure, that they were sworn enemies. After Radhey was taken to the hospital, the doctors tried their level best to save him, but they could not, and he died today morning after an illness of about four and half days. The doctors refused to give a death certificate, as they did not know the illness Radhey was suffering from. Meanwhile the relatives of Radhey actually lodged an FIR in the police station, in which they alleged that Suleiman had poisoned Radhey, and he should immediately be taken in custody. Apparently the relatives of Radhey had some political clout too, so the police had to act fast. Now they have sent this body to me. My job obviously is to find out how Radhey actually died."

"Very interesting indeed. That explains the big mob outside your mortuary. When I came to meet you, I was surprised to see several people sorrounding this mortuary several of whom were toting cellulars."

"Yeah, they are very influential people, and apparently they would leave the mortuary only after they have come to know of the cause of Radhey's death. The pressure on police was so much that they had to arrest Suleiman."

"What does Suleiman say doctor?"

"I have talked to Suleiman myself. The police has also talked to him. He says he has absolutley no hand in this killing. He has hired a lawyer for his defense and he is pressurizing the police by saying that they can not arrest his client without any solid evidence. So the police are finding themselves in a Catch-22 situation. As you can understand, I have been showered upon with a very heavy responsibility."

"Yes indeed. I can understand that. Now where do you start from?"

"Tarun, I have already started actually. Whenever a death occurs in a factory, I make it a point to visit the factory first and see what kind of activities were going there. I found that Radhey was involved in making soldering flux by putting zinc scrap in hydrochloric acid."

"Please explain this to me in some great detail doctor."

"Tarun, in several industries there is a "rough and ready" practice of producing zinc chloride to provide a soldering flux by putting zinc scrap in hydrochloric acid. This is actually not recommended as sometimes a very poisonous gas arsine may form in this process. The zinc scrap may contain arsenic as an impurity, and when arsenic acts with hydrochloric acid, it forms arsine (AsH3) a very dangerous gas."

"So you think Radhey died of arsine gas?"

"I can't say for sure at present, but after you know more about this interesting gas, you can make a guess yourself."

"Looks like we are on the trail of yet another interesting poison. Doctor please tell me more about arsine gas."

"Tarun, arsine is a very toxic gas, a molecule of which contains just four atoms - three of hydrogen and one of arsenic. It is a colorless inflammable gas. It is supposed to have an odour of garlic, but it is not always apparent, especially when a person is suffering from common cold. It is an unstable compound which when exposed to light or moisture, decomposes to deposit arsenic. It is heavier than air, its vapour density being 2.68 times that of air. You might be surprised to know that the German chemist Gehlen died of accidental arsine poisoning in 1815."

"Oh, I didn't know that."

"Tarun, arsine is one of the most poisonous gases known. It can kill outright. Even brief exposure to moderate concentrations can cause serious illness. I will give you some figures which will tell you something about the killing power of this gas. The four most poisonous gases are carbon monoxide, phosgene, chlorine and arsine. Inhalation of carbon monoxide in concentrations of 1000 parts per million (ppm) for a few minutes can cause death. The equivalent figures for Chlorine and Phosgene are 400 ppm and 50 ppm respectively, meaning thereby that they are more poisonous. Obviously the lesser concentration required for killing, more poisonous the gas. You would be surprised to know that in the case of arsine, only a concentration of 10 ppm inhaled for about half an hour could be dangerous. And at such low concentrations, the pecualiar garlic odor of the gas may not be apparent at all. The safe maximum concentration of carbon monoxide - generally considered by all to be very toxic - is 100 ppm, while that of arsine is just 0.05 ppm. This can give you some idea of the lethality of this gas"

"Oh, sure. From the figures it appears to be about 2000 times more poisonous, which is remarkable. Especially considering the fact that everybody considers carbon monoxide to be a very deadly gas."

"Exactly. Like carbon monoxide, arsine is a cumulative poison too. This means that it is excreted much more slowly from the body than it is absorbed. This results in gradual accumulation of the poison in the body which can be very dangerous. A good simily is of a tank, in which poisonous water is entering much faster than it is being let out. This would ultimately result in overloading of the tank with the poisonous water."

"Yes, I understand. But what is the significance of a cumulative poison doctor?"

"Tarun, it means that repeated or prolonged exposure to even a very low concentration can be dangerous. Thus a cumulative poison - that whose excretion rate is slower than that of its absorption- is a much more dangerous poison, than a non-cumulative poison. The hazard of arsine gas exists in a number of industries including the refining of metal, the manufacture of corrosive acids, galvanizing and electroplating. It is also a risk in laboratories. There was a time when the use of wall papers colored with pigment which contained Scheele's Green, yielded arsine in the home, when acted upon by a mould. This could create severe poisoning in the inmates, especially considering that arsine is a cumulative poison."

"Just a minute doctor. What is Scheele's Green?"

"Tarun, Scheele's Green is a popular name for cupric arsenite. Its formula is Cu3(AsO3)2.2H2O. It is named thus in the memory of the famous Swedish Chemist Kark Wilhelm Scheele (1742-1786). It is a brilliant green pigment which was once used for paints, but since it is a potentially poisonous compound, it is no more used now. When mould acts on this compound, arsenic may get combined with hydrogen molecules and may form arsine, which may be very poisonous. Arsine may be produced in quite a few other remarkable ways."

"What are those doctor? Please tell me."

"Tarun, I know of a unique case of industrial poisoning by arsine in which three men were poisoned - one of them fatally. They were engaged in unloading fish scrap from the hold of a wooden schooner. The close, warm atmosphere promoted bacterial activity and, in turn, the production of arsine."

"Oh that is indeed quite unusual."

"Yes. Another likely source of arsine is the interior of tanks used in the preparation of sulphuric acid from iron pyrites (sulphide). Some of the deposits in these tanks was hard and had to be scraped from the walls. It contained upto 45% of arsenious oxide. The production of arsine from this material was unsuspected for quite some time. In yet another case, a person had cleaned a water jacket by pouring freshly diluted hydrochloric acid into its pipes. Fumes were liberated and he was in close contact with them in an unventilated room for about half an hour. The acid contained an "inhibitor", which proved to be a mixture of sodium arsenate and aniline hydrochloride. Arsine was produced from the inhibitor n the presence of nascent hydrogen and the man was severely poisoned."

"Oh, I see. Arsine can be produced in most unusual circumstances. It does appear to me that Radhey too got involved in arsine poisoing."

"Yes, it became apparent to me, when I came to know that he was involved in making the soldering flux by that precarious method, which I have described you just now. My suspicion was confirmed to a great extent when I heard that he had passed dark urine. This was because of the presence of hemoglobin in the urine."

"Why should hemoglobin appear in the urine in a case of arsine poisoning?"

"Arsine is a deadly poison tarun. It hemolyses (breaks) all the Red Blood Cells of the body. This liberates hemoglobin which ultimately finds its way in the urine which become dark. I have made some slides of the blood of this patient, and you can see under the microscope that all the R.B.C.s are broken. This is a very strong indication that he had died of arsine poisoning. Moreover his kidney tubules are blocked by these broken R.B.C.s which is another finding in favour of arsine poisoing. Coupled with his peculiar history, I am sure Radhey died of arsine poisoning, which is an accidental poisoning. Suleiman had nothing to do with it. Come, let us tell the police about it."

"Very clever indeed. This was a most interesting discussion doctor. Without your masterly deduction, police could have unnecessarily went on harassing Suleiman. Radhey's relatives and other people might have thought, it was a case of killing by Suleiman. Tell me what are you going to tell me the next time?"

"Tarun, next time, I would tell you about death by aflatoxins. "