THE FOLLOWING ARTICLE APPEARED IN THE

AUGUST 1997 ISSUE

THE POISON SLEUTHS

POISONING BY METHYL BROMIDE

-Dr. Anil Aggrawal

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

"Good morning Tarun. The name of this 3 month old girl is Varsha. She is the daughter of RadheyShyam and Sita who were living in the ground floor of Mahajan's house as tenants. RadheyShyam and Sita are a young couple in their late twenties. Mahajan was living with his family on the first floor. He had been asking RadheyShyam and Sita to vacate his house for quite sometime but they refused to vacate the house. Many times Mahajan had threatened them with dire consequences, but nobody took it seriously..."

"So obviously he killed Varsha to teach them a lesson?"

"Don't jump to conclusions Tarun, I haven't finished yet. Yesterday, i.e. on 20 August, RadheyShyam, Sita and their daughter Varsha had gone to attend a marriage party from where they returned late in the night. On entering their house, both RadheyShyam and Sita experienced a foul smell. However, as they had experienced smell from the sewage during previous days, they took little notice of the smell. These sewage problems had resulted in maintenance work on the sewage pipes in their street just after noon on the very same day. They nourished the infant and went to bed in their room at about 10.30 pm., keeping the door open to the infant's next door room. Two hours later at 1.30 am and about 3 hours before expected, Varsha started to cry vigorously. The mother took care of the child, who vomited and had severe diarrhoea. At the same time the parents were alarmed by a "burning" sense in their eyes, throat and mouth, and they also started to vomit. They contacted a local doctor on phone but he didn't turn up. Without knowing what was happening in the house, they realized that something very wrong was going on, especially as Mahajan was threatening them with dire consequences for quite some time. They came out of their house immediately along with their child, called a Taxi and went to Sita's parents' house to spend the rest of the night. Subsequently Varsha became drowsy and unable to drink water or milk. At noon on 21st August, Sita's parents and all the other adults went to the city's hospital arriving there at about 1 pm. But unfortunately she was declared dead on arrival."

"Oh, that's indeed very sad and depressing. So what do you think was going on in the house?"

"Tarun, the whole scenario and symptoms of the three persons involved point very strongly in favor of one poison- methyl bromide."

"What? Methyl Bromide? Doesn't sound like a common poison to me. Please tell me more about it."

"Sure Tarun. Methyl Bromide surely is not commonly known, but it is indeed a very interesting poison. Methyl Bromide (CH3Br) is also known as bromomethane, monobromomethane, Embafume or iscobrome. Pure methyl bromide is a colorless gas that is heavier than air. Thus it is one of those rare poisons which occur as gases. Odorless and tasteless in low concentrations, it has a musty, acrid smell in high concentrations. That's why RadheyShyam and Sita noticed that strange smell on coming back from the marriage party."

"Doctor, who in the world uses methyl bromide, and why?"

"Tarun, Methyl Bromide is in relatively widespread industrial use as a fumigant and insecticide because of its effective penetrating power and absence of fire or explosion hazard. Occupational exposure to it also occurs frequently. Nobody knows about Indian figures, but it is estimated that about 75,000 American workers are occupationally exposed to this gas annually. Its toxicity is severe and despite safeguards, cases of acute and chronic intoxication occur, chiefly in fruit and tobacco industries, because of its use in these industries as a fumigant and an insecticide. It has also been used as a refrigerant, solvent, methylating agent, and in dyes and fire extinguishers."

"Quite interesting. How can poisoning occur due to this gas?"

"Tarun, toxic exposure to this gas can occur by inhalation as in the case of Varsha or by skin absorption. Body tries to excrete this poison out of the system. Excretion takes place mainly through the lungs. The remainder is metabolized in the body, and inorganic bromine is excreted in the urine. In European countries cases of accidental poisoning due to fumigation of houses are quite well-known."

"But at the time of fumigation, the houses are vacated. How can one possibly get poisoned?"

"Yes, you are right Tarun, yet poisoning has occurred in sinister ways. In many European countries, the houses are made up of wood, and the European house-bores (Hylotrunes bajulus) occasionally invade old wooden houses. To kill these house-bores methyl bromide is often used for fumigation, and as you rightly say, the houses are indeed vacated for fumigation. But cases are known in which the gas has entered the sewage pipes of the fumigated house (which of course had been vacated) and from there it travelled to the main sewage pipe. From there it gained access to the adjacent houses or even to houses at quite some distance. Of course, it can occur only if the houses in question don't have the water-locks that are now obligatory in all sewage pipes. Now you must be able to understand why you have water-locks in the sewer pipes of the places where you relieve yourself. If these water-locks were not made obligatory, gases from the adjacent houses, or even from the main sewer could easily enter one's house."

"Quite interesting. Have people died in such a way?"

"Yes, I am personally aware of persons dying in such exotic manner. These cases are frequently reported in learned journals too."

"Doctor, how does methyl bromide kill a person? Since bromine itself is a poison, I would tend to believe that the bromide ion in the methyl bromide molecule does the damage."

"Tarun, it would indeed appear so, but it is not true. I will give you certain figures which will make things very clear in your mind. Normal bromide levels in adults are about 0.3-0.4 mg/dL and come primarily from bromide residues in fumigated foodstuffs. If one ingests an inorganic bromide, such as sodium or potassium bromide then he does die of bromine toxicity. Technically we know it as bromism. In the case of a fatality due to inorganic bromide ingestion, the blood levels of bromine are quite high- almost 300 mg/dl, which as you can see are almost 1000 times the normal level. Levels lower than this produce serious toxicity but not death. For instance levels of 100 mg/dl produce toxic symptoms and level of 200 mg/dL produce serious toxicity. But in the case of methyl bromide intoxication, which is an organic bromide, death may occur when the bromine levels of the blood are as low as 8-9 mg/dL. This clearly means that bromide ion is not responsible for the death in the case of methyl bromide intoxication."

"Then what is the cause of death in these cases?"

"Tarun many important enzymes in our body contain important entities called Sulfhydryl groups. These groups can chemically be represented as "-SH". Methyl bromide releases methyl ions in the body, which combine with these sulfhydryl groups and make the enzymes ineffective. This is technically known as methylation of the sulfhydryl groups. Enzymes in the central nervous system seem particularly prone to this destruction. That is why a patient suffering from methyl bromide poisoning displays neurological symptoms quite prominently. Major manifestations are vomiting, headache, vertigo, gait disturbances, double vision, delirium and seizures. All the three persons in question have displayed several of these symptoms. Since methyl bromide affects the brain in a major way, in cases of death, the main changes are observed in the brain. The brain is water-logged and swollen, which we term as edema of the brain. The coverings of the brain, or the meninges are red and there may be hemorrhages under them. Loss of neurons have also been seen at times."

"Did you see these changes in the body of Varsha?"

"Yes, Indeed I did. But the most interesting finding was the bromine levels in her blood which are almost 17 mg/dL. As you know this is much above the normal limit and does indicate that she was exposed to methyl bromide."

"Then surely Mahajan has done the trick. But how did he introduce the gas in RadheyShyam's house?"

"Mahajan was asking RadheyShyam and his family to vacate his house for quite some time, but they were not doing so, so he decided to finish them off in a very clever and sinister manner. I must admit that I have never heard of such an exotic method to kill an entire family. In fact, he would have easily got away with the murders, had the police not decided to contact me..."

"Doctor, I am getting curious. How did he do it?"

"He contacted an insecticide company and bought a cylinder of Methyl Bromide gas on the pretext that he wanted to fumigate his crops. From the cylinder he connected a pipe and inserted the other end of the pipe into the chimney which leads to the kitchen on the ground floor. Since the top of the chimney is on the barsati above the first floor, where Mahajan was living, it was accessible to him. After making this elaborate arrangement, he opened the valve of the cylinder releasing the gas in the chimney. The gas being heavier than air, quickly "dropped down" into the kitchen and from there it seeped into the entire ground floor. When RadheyShyam and his family entered their house after attending their party, Mahajan had literally converted their place into a gas chamber! RadheyShyam showed presence of mind and left the house quickly with his family, otherwise even he and his wife would have died. I have asked the police personnel to look specifically for a gas cylinder in Mahajan's house. Oh here comes the police inspector... What! you did find the methyl bromide cylinder in his house. Look Tarun, I was right. My investigation has indeed worked. The police can now successfully prosecute Mahajan."

"Fantastic! And many thanks for letting me know about such an interesting poison. You indeed are a great poison sleuth. What are you going to tell me next time?"

"Tarun, next time I shall tell you about ratti seeds, which as you shall see is another important poison. This is a vegetable poison, as you shall see. "