THE FOLLOWING ARTICLE APPEARED IN THE

JUNE 1998 ISSUE

THE POISON SLEUTHS

DEATH BY SELENIUM

-Dr. Anil Aggrawal

"Good morning doctor. Oh, my God, what are you doing today? You have the dead body of a young boy today. And his mouth is smelling as if he had eaten garlic before his death. What happened to him? Please tell me."

"Good morning Tarun. The name of this young boy is Shyam and he is about 3 years old. His father is an old military hand, and a lover of guns. He was the only child of the family. His mother is a housewife. Yesterday his parents left home to visit one of their relatives, leaving the child with the maid, a young woman named Anita. The maid knew the child well, and Shyam was quite comfortable with her. It appears that for some time, the maid went to the bathroom. At least that is what the maid's version is. When she came back, she saw the child rolling on the ground, retching and vomiting. She immediately telephoned the parents. They rushed to the house and took Shyam to the hospital. When seen in hospital, he was moaning and making purposeless movements with his limbs. Salivation was profuse and he had a strong smell of garlic in his breath- as you have rightly observed now also. Doctors were trying to diagnose what his illness was, but within 45 minutes of his arrival at the hospital, he died."

"Oh, that is most terrible. So the police must have now handed over his dead body to you to find out how he actually died?"

"Yeah, that's true. Anita is actually a decent woman, and wouldn't do any mischief. But the child's parents are obviously in a very terrible grief, and wouldn't like to spare anyone. The police wouldn't want to spare anyone either in this heinous death. So Anita is not totally out of suspicion. And I have to tell the police how he actually died."

"So what have you found out doctor?"

"Tarun, when I found the strong smell of garlic from the boy's breath, immediately a bell rang in my mind. I asked the parents if they used garlic at home, and they replied in the negative. This set me thinking......"

"Really? So the boy had not eaten any garlic. But I can swear he has eaten garlic. He is smelling so bad of garlic."

"Yeah, that's right Tarun. But I must tell you that there are a few poisons which when ingested give rise to almost the same smell. These are selenium, phosphorus, arsenic, tellurium and dimethyl sulfoxide."

"Oh, so the boy must have been given either of these poisons?"

"Well, let us not jump to conclusions Tarun. These are the possibilities, but certainly the boy might have died of some other cause too. For instance he might have died of some natural illness. But I have enquired the parents if he ever suffered from some major illness, and they have answered in the negative. Then I looked at the body for some obvious injury marks. They are also not present. So it does appear to me that he died of some poison, and the poison is most likely to be one of those I already mentioned."

"So how are you going to find out how Shyam actually died?"

"Tarun, when I was making enquiries from the parents, I came to know that Shyam's father was a lover of guns. This immediately alerted my mind in one particular direction. Most gun lovers keep a special compound with them; it is called gun-bluing compound. It is actually selenious acid or hydrogen selenide. When rubbed on the guns, it gives them a beautiful metallic sheen. It seemed very probable to me that Shyam had accidentally ingested the gun bluing compound, especially when we take into account that his breath was smelling of garlic. I asked his father if he owned gun-bluing compound, and he was quite surprised how I actually came to know about it. I told him that it was just a hunch. He told me that he did own a bottle of this compound. I asked him to check the bottle. He used to keep the bottle in an open Almirah. When he checked the bottle, he found it open and it was partly empty. He thought that may be he had accidentally spilled the contents over........."

"Oh, great. So just by making one or two nice observations you could diagnose the cause of death. But of course the court will require more rigorous proof. Before we go on to that, would you please tell me something about selenium doctor? It is beginning to appear to be such an interesting substance to me."

"Oh sure Tarun. Selenium is a nonmetallic element closely related to sulphur. It is found commercially in steel and copper alloys and metal bluing solution as we have seen just now. It is also used for making stained glass, ink and even cosmetics. A suspension of selenium disulphide has been used as a shampoo in the treatment of seborrhoea, which is a kind of skin disease. It is still used, in a 2.5% aqueous solution of selenium sulphide, as a shampoo for the treatment of dandruff!"

"Really. I do use a shampoo for dandruff. So does it contain selenium?"

"I don't know. It may. You must check its contents which must be written on its wrapper. In any case selenium is not absorbed through unbroken skin, so if you use an anti-dandruff shampoo you are quite well off, if your scalp is not abraded. But if it is, the selenium may get absorbed. If absorbed, it may cause motor neurone disease, which is a kind of neurological disorder. Furthermore if someone accidentally ingests such a shampoo, he may be in trouble."

"Alright. The first thing I will do today, is to check the contents of my shampoo. How else does selenium occur?"

"Naturally it occurs in the surface soil in certain areas, and is readily absorbed by plants, including grain and vegetables growing in these areas. Herbivorous animals feeding on these plants may accidentally get poisoned by selenium. Endemic poisoning of herbivorous animals and in hens was first described under the name "alkali disease". It could have been the cause of "blind staggers" in cattle in South Dakota where the selenium content of the soil is high."

"What is "blind staggers" doctor? Please tell me."

"Tarun, it is a disease of cattle in which they show impaird gait and vision- hence the term "blind staggers". In addition, the animals show wasting, stomach upsets, liver damage, bizarre growth, loss of hair and hooves and sometimes sterility. South Dakota is a state in the US, where the soil is excessively rich in selenium. So naturally this selenium is taken by plants and grass too. Animals who fed on this vegetation showed signs of selenium poisoning. And this disease was given the name "blind staggers. Extensive studies have shown that similar symptoms may occur in man, and as grain and vegetables may be conveyed considerable distances these symptoms may occur well outside the recognized endemic areas."

"What are the endemic areas"

"By this term, I mean those areas where the soil is known to contain high amounts of selenium. There are some very interesting facts connected with selenium. For instance in 1901, it was suggested by some scientists, that some of the toxic manifestations attributed to arsenic in beer were in fact due to the presence of selenium in addition to arsenic."

"Well, this point is not very clear to me."

"Tarun, beer generally contains some arsenic. And heavy beer drinkers may show some signs of arsenic poisoning too. These scientists suggested that beer may contain selenium in addition to arsenic, and the toxic symptoms may be due to that too. In fact when the Government made a Royal Commission on Arsenical Poisoning, one of these scientists actually gave evidence that such a thing was possible"

"Doctor, are all selenium compounds poisonous?"

"Yeah, almost all. Many selenium compounds are very irritating or even corrosive to the skin, mucus membranes and respiratory tract. Many selenium compounds were formerly used as plant insecticides, but they have been abandoned now because of their toxicity to man. Selenium oxychloride destroys skin on contact. Selenious acid or hydrogen selenide about which we have just talked, is very caustic when ingested. Fatalities from accidental ingestion of gun bluing agents are however possible. One of the reasons for this is that hydrogen selenide is colorless and odorless, so children may accidentally take it."

"But just now you said that hydrogen selenide has garlicky odor. In fact, the child is smelling so bad of garlic, and that actually put you on trail of arsenic"

"Tarun, I never said hydrogen selenide is garlicky in odor. I only said that in selenium poisoning one has garlicky odor. Let me tell you how these two statements are compatible. Garlicky odor is actually due to the excretion of dimethyl selenide in the breath. In the body, various selenium compounds can actually get converted to this compound to give rise to garlicky odor. So although selenious acid is odorless in itself, it can give rise to garlicky breath. I may tell you that the garlicky breath of selenium poisoning is so characteristic, that even its discovery itself is attributed to it."

"Really? How? Tell me. I like listening to interesting true science stories."

"It is said that the housekeeper of the house where Berzelius (the Swedish chemist who discovered Selenium) lived, complained that he had eaten too much garlic. But it was due to his having examined a selenium deposit in a sulphuric acid chamber. He had inhaled fumes which were probably those of dimethyl selenide. This set Berzelium thinking and he went on to discover selenium"

"Oh, that is indeed very interesting doctor. Now tell me in how many different ways selenium toxicity can be produced?"

"Tarun, toxicity can be produced in a number of ways. One of the ways of course is the direct ingestion of selenium either suicidally, homicidally or accidentally. However, no case of homicidal selenium toxicity has however been reported till now in literature, but it is certainly possible, especially as some of its compounds such as arsenious acid are colorless and odorless. But of course arsenious acid is very corrosive and when one is given this poison mixed in some liquid, he would at once come to know about it, from the corrosive action in his mouth. It is like having drunk dilute hydrochloric acid which also is colorless but very corrosive. Selenium poisoning is also recognized as an industrial hazard in the metal refining, glass making, electrical and chemical industries. And as we have seen, sportsmen and military people who keep shotguns in their homes may also keep gun-bluing compound, which is selenious acid, which can also cause accidental poisoning. Since it is a colorless and odorless fluid, it must be kept out of reach of children. Recently there has been some evidence that selenium is a naturally occurring antioxidant in the body and may be anticarcinogenic. Because of these suggestive findings selenium in various forms is being consumed in megadoses as a dietary supplement. The Centres for Disease Control (CDC), in USA reported 12 persons with nausea, vomiting, nail changes, fatigue and irritability from excessive selenium intake. About half of the patients experienced hair loss, and about one-third lost nails. Other symptoms included watery diarrhoea, abdominal cramps, dryness of hair, paresthesias (abnormal sensations) and garlic breath odor."

"Doctor, can you tell me how selenium actually causes the death of a person?"

"Tarun, there are certain enzymes within our body which contain sulfhydryl groups, i.e. -SH groups. These enzymes are very necessary for cellular respiration. Selenium bonds sulfhydryl enzymes and causes poisoning. I may tell you that arsenic also does the same, and is thus an equally deadly poison. Other compounds of selenium besides selenious acid are dangerous too. For instance, as sodium selenate, selenium is highly toxic. Acute selenium poisoning produces primarily central nervous system effects, including convulsions. The initial symptoms are nausea, vomiting and a metallic taste in the mouth, dizziness and extreme lassitude. Garlicky odor of the breath and sweat is very characteristic. In industrial situations, a worker may slowly absorb selenium in his system. He will then be said to have been suffering from Chronic selenium poisoning or chronic selenosis. It is manifested by garlic breath odor, stomach and intestine distress, upper airway irritation, metallic taste in mouth and inability to smell. The odor of garlic is perhaps the most characteristic feature. I may tell you that more than half the absorbed selenium is excreted in urine, the remainder in the faeces and in the breath as I have already told you. In endemic areas, urinary excretion of selenium may be as high as 200 micrograms/100 ml without obvious symptoms, while in industry symptoms have been noted with as little as 5-13 micrograms/100 ml."

"Doctor, how much selenium can actually kill a person?"

"Nobody knows for sure Tarun. But from the various poisoning cases that have come to light, doctors are of the opinion that the fatal dose is about 4 mg/kg body weight. That is, if a person weighs 60 kg, about 240 mg of a selenium compound would be enough to kill him. This, as you can see is quite a low dose, and this makes selenium a very dangerous poison. Its fatal period is about half to one hour. This means that after ingestion, a person would usually die within this period."

"Oh, now I know so much about selenium. Now I am ready to listen to you, how you are actually going to prove in the court that the child did die of selenium poisoning, and who killed him?"

"Tarun, we have already noted the garlicky odor which is a strong indicator towards selenium poisoning. Furthermore there is congestion (redness) and edema (swelling) of the gastric mucosa, the membrane which lines the stomach. The most important thing is that I have analysed Shyam's organs chemically, and have found high amounts of selenium in them. I have also chemically analysed the gun bluing fluid found at his house and it was found to contain 1.81% of selenious acid. I do not think Anita gave this poison to Shyam. She is an illiterate woman and does not know about the toxicity of gun-bluing compound. Moreover she had no motive to do so. Gun-bluing compound, as I told you earlier, can very easily be ingested accidentally as it is colorless and odorless, and doesn't alarm the person at all. It does appear to me, that when the maid was away, Shyam wandered towards his father's almirah, which was open. He looked at the bottle and was quite curious. Children like to put everything in their mouth, and in his naturally curiosity, he drank some of the liquid, which was responsible for all his symptoms. Well these are my observations only, and it is for the court to decide what actually happened. I can only tell the court with certainly that the child did die of selenium poisoning, and most probably Anita is not guilty."

"Oh, how very clever of you doctor. This was a most interesting discussion. Tell me what are you going to tell me the next time?"

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