Cadmium Bahaya

MY FORENSIC ARTICLES IN SCIENCE REPORTER : THE FOLLOWING ARTICLE APPEARED IN THE AUGUST - SEPTEMBER 1998 ISSUE

THE POISON SLEUTHS POISONING BY CADMIUM - Dr. Anil Aggrawal

"Good morning doctor. Oh, my God, what are you doing today?

 You have the dead body of a young girl today. What happened to her? Please tell me."

"Good morning Tarun. The name of this young girl is Kanta, and she died this morning in the hospital. She was a chemistry student and about 19 year old. Yesterday night she took part in a party thrown by Sohan who was her classmate. Three other students also participated in that party, two of whom were girls. So in all there were 2 boys and 3 girls, including Kanta and Sohan. All are chemistry students studying in a local college. At the party, Kanta took some food and some soft drinks. Soon after that she complained of a choking sensation around her throat and excessive salivation. She also had a feeling of nausea and vomited several times, and had diarrhoea too. She was rushed to a local hospital, where the doctors diagnosed that she was suffering from gastroenteritis, a kind of infection of the stomach and intestines which gives rise to these symptoms. It was thought that she had some form of food poisoning. But what was surprising was that the other four students did not have any problem whatsoever. Had they suffered the same symptoms, the death could have been passed off as a natural death due to gastroenteritis, but since all the others are well off, the police has suspected some foul play and has brought her dead body before me. Of course they have requested me to conduct a post-mortem on the dead body and tell them about the cause of death."

"Oh, so how are you going to find out the cause? Do you think that there has been some foul play somewhere?"

"Well, anything is possible in this world. I contacted the doctors in the local hospital where she was taken, and also went through her hospital case sheet. What caught my attention was that Kanta was suffering from severe aches and pains too. And these aches and pains started only after she drank the soft drinks, and ate the foodstuff at Sohan’s house. I do not know of any form of gastroenteritis where you also get generalized aches and pains...."

"So what are you trying to arrive at?"

"Tarun, I have made a detailed study of the symptoms which Kanta displayed, and a very unusual poison is coming to my mind as the possible cause of her death"

"Doctor, what is that poison? Please tell me. I am getting curious."

"Tarun it is a very unusual poison- cadmium chloride."

"Cadmium Chloride? Never heard of its being used as a poison. Is it a poison really?

"Yeah it is indeed a very deadly poison. If fact its very discovery is related to its toxicity..."

"Really? How? Seems like we are in for another of your interesting historical stories."

"Yeah, it does make an interesting story. The story starts in the early part of 19th century. Zinc oxide was then widely used for a number of ailments, and was freely available at chemists shops. To ensure that the medicines were not adulterated, the Government of Germany in those days employed district physicians. Their job was to go to chemists’ shops and find out if the medicines they sold were spurious or not. One such physician named Rolow – who was incharge of the province of Hannover - got the reports of toxicity from zinc oxide being sold at local chemists’ shops. From the reports of symptoms, he suspected arsenic poisoning (for details of arsenic poisoning, see Science Reporter February 1997 issue). So he went around from shop to shop, collected zinc oxide samples from the shops and put them to test. One of the standard methods in those times to test for various oxides was to treat them with hydrogen sulphide. This caused various metallic sulphides to form which could be detected from their color. When Rolow treated zinc oxide with hydrogen sulphide, he got a yellow precipitate strongly resembling the sulphide of arsenic. From this he concluded that the samples of zinc oxide were indeed impure - they contained arsenic oxide as well."

"So did they really contain arsenic?"

"Wait. The local supply of zinc oxide was made by one influential businessman - a man called Hermann. He was also a chemist by profession. He got his own samples tested for arsenic in his own way. He employed all chemical tests known for arsenic at that time and came to the conclusion that his samples did not contain arsenic at all. On the strength of his analysis, he applied to the local authorities, requesting them to restart his supply of zinc oxide to the local chemists’s shops."

"So how was this controversy resolved?"

"To resolve the controversy, the authorities of Hannover employed the services of a very reputed chemist of those times- Professor Friedrich Stromeyer (1776-1835), head of the department of chemistry at the Göttingen University. The added advantage was that he also held the post of Inspector General of all Hanover chemists’ shops. Hermann’s factory was situated in a place called Schönebek. Samples of zinc oxide were sent from Schönebek to Göttingen where Professor Stromeyer got to work. Quite intelligently first he investigated how zinc oxide was being produced. He found that chemists in Schönebek calcined zinc carbonate to obtain zinc oxide. So he started from zinc carbonate instead, and heated it strongly. To his surprise he got a yellow colored compound. He was expecting zinc oxide, which as we all know is a white colored compound. He asked both Hermann and Rolow to explain that."

"Oh, so even the Great Stromeyer was confused, is it?"

"Not in the least. On the contrary he gave enough opportunities to both sides to explain their stand before he got to work. Interestingly both sides gave wrong explanations. Hermann explained away the color by saying that the samples contained iron, although it is not known how that explained the yellow color. For him it was better to explain by resorting to something like iron which is a natural constituent of the body, and can do no harm to anyone. Well, to be sure, even iron can be poisonous, but for that it should be administered in very large quantities. Rolow, who was intent on getting Hermann’s factory closed, explained away the color by contending that the samples contained arsenic. After listening to both sides, Stromeyer got to work and discovered a hitherto unknown metal in the samples. It looked very much like zinc, but could easily be separated from it by means of hydrogen sulphide. So much did it look like zinc that Professor Stromeyer preferred to call it Cadmium - after cadmea, a word which in Greek means zinc ore."

"Oh, very interesting indeed!"

"In fact how the zinc ore came to be called cadmea is in itself an interesting story. Legend has it that a Phoenician Cadmus was the first to have found a zinc rock and to notice that it gave a golden tinge to copper during smelting. It is from his name that zinc ore finally came to be called Cadmea. You may be surprised to know that naming chemical elements was a big fashion in 19th century Europe, because new and new elements were discovered almost every year, and it became fashionable to name elements after various Gods, legends, scientists, countries, even rivers. Element Rhenium for instance is named after the German river Rhine! In 1818, when Professor Stromeyer published his paper on Cadmium, many people came forward with the suggestion that they had already discovered that element first and even suggested names for this new element. German chemist Kersten, for instance, suggested that the new element be called melinium (yellow) after the color of its sulphide. Two other scientists Gilbert and John proposed two more names. One of them suggested that it be called junonium (after the newly discovered asteriod Juno in 1804) and the other suggested that it be called klaprothium, after the German chemist Martin Heinrich Klaproth (1743-1817), but ultimately the name given by Stromeyer stuck."

"Oh, this is most interesting. Tell me some other important facts about Cadmium."

"Tarun, Cadmium is used in a wide range of industrial processes, which include electroplating to impart corrosive resistance to ironware. Cadmium compounds are used as pigments, as components of batteries and photographic materials and cadmium is also used as a plastic stabilizer. Cadmium sulphate in a 1% solution, is a constituent of a shampoo used in the treatment of seborrhoeic dermatitis and dandruff."

"So we were talking about the Cadmium poisoning. How can it occur?"

"Cadmium poisoning can occur accidentally in a variety of circumstances. In the 1940s, it was usual for people to have their kitchenware electroplated with cadmium, as this makes them corrosion resistant. In the very beginning, Cadmium coating was deposited by immersing the metallic ware in molten cadmium...."

"Sorry to interrupt you doctor, but melting cadmium must be quite a task. That too for just coating metals. Wasn’t it a very costly process?"

"No, not at all. Cadmium melts very easily. It’s melting point is only 3210 C. In fact, its such a low melting point makes it a very suitable candidate for making low melting alloys. Among them Wood’s alloy containing 12.5 percent of cadmium was developed as far back as 1860 by a British Engineer Wood. These low melting alloys are used as solders and as the material for delicate and intricate castings, as well as in automatic fire-warning systems. Okay so I was telling you about the cadmium coating on kitchen ware. Later on, the coating was done with the help of electroplating. Unfortunately organic acids, many of which are used in day-to-day cooking such as vinegar (acetic acid), imli (tartaric acid) and lemon (citric acid) can dissolve cadmium from the thin electroplated layer, and this caused several cases of poisoning. In one accident which involved three adults and five children, the source of poison was "lemonade" ices prepared with citric acid in metal trays of a reconditioned refrigerator. All were sick and four also had diarrhoea, but recovery was complete within 24 hours. The citric acid solution contained 279 ppm (parts per million) of cadmium and it was estimated that each ice contained about 3 mg of cadmium. The ill effects resemble those of zinc poisoning. It is thought that the salts formed by organic acids are converted into cadmium chloride by HCl in the stomach. When the cause of these poisonings was discovered, the practice of cadmium electroplating was abandoned. But by no means are the incidences of accidental poisoning by cadmium ceased altogether. As late as in 1981, a case of accidental cadmium was reported. In this case, the victims inhaled fumes from a plated shelf of a refrigerator, used as an improvised barbeque grill!"

"Oh, that is certainly most extraordinary!"

"Yeah, that is right Tarun. Accidental cases of cadmium poisoning can also occur from cadmium fumes and dust. Cases have been reported where the poisoning occurred in some women who were using a cadmium powder to clean silver. These cases occur especially if the cleaning was being done in small, ill-ventilated rooms. It is interesting to keep in mind that inhaled cadmium is about six times more dangerous than ingested cadmium. Thus poisoning from inhaled cadmium fumes is much more dangerous.

We have seen that in earlier times, metals were frequently electroplated with cadmium. Interestingly this practice has given rise to some cases of "delayed" poisoning now. Scrap metal from those times – if cut, dismantled, or recycled today, especially if with the help of oxyacetylene torches – can give rise to dangerous levels of cadmium fumes. Cases of fatal poisoning in such circumstances have been reported. It is important to realize that since cadmium was once used to electroplate metals, and there may be several such metallic objects in an average house, a housefire can give rise to cadmium fumes, and firemen must wear protective masks. There was a time when carbon tetrachloride was used as a fire extinguisher. But when carbon tetrachloride came in contact with hot metal surfaces, it gave rise to the poisonous phosgene (see Science Reporter Jan 1998 "Death by Phosgene"). Cadmium fumes, if produced during these fires were often confused with phosgene gas, and this caused serious blunders in treatment of such poisoned victims. But now since the use of carbon tetrachloride in fire extinguishers has been banned, chances of such graves mistakes are very remote."

"This is very interesting. Have cases of poisoning occurred in such circumstances?"

"Oh yes. In one interesting incident which occurred in 1956 in a chemistry laboratory in Leeds (Great Britain), some cadmium propionate was being dried in an oven for experimental purposes. This is a safe procedure as long as the temperature does not rise above 1000 C; above this temperature fumes of cadmium oxide and propionic acid are produced. Because of an inadvertent mistake, although the temperature of the oven reached 1600 C, it was read only as 600 C. Because of this, an explosion occurred, followed by a fire, and thick red fumes were seen to be coming out of that room. Four of the firemen, who entered the room to put out the fire inhaled those fumes, and one died after 6 days. On postmortem examination, significant amounts of cadmium were found in his internal body organs."

"Oh, I see. Is cadmium found in some of our day to day products too?"

"Tarun, Cadmium is found in significant amounts in unfiltered cigarettes, and this can be a cause of poisoning. Twenty unfiltered cigarettes a day can yield 6 mg of cadmium, of which the smoker may retain upto 65%."

"Doctor you said that Kanta was suffering from muscle aches and pains and from this you deduced that she might be suffering from Cadmium poisoning. Can you elaborate on that?"

"Oh, sure. This symptom is so prominent in Cadmium poisoning that it has even given a name to a disease caused by Cadmium. Let me elaborate. An outbreak of food poisoning due to Cadmium occurred in Japan in 1945. The syndrome has been called itai-itai disease, which when translated in English means ouch-ouch disease. The syndrome has been so called because it caused severe pain in the back and legs (which forced the victims to cry "ouch-ouch" so to say!). In more serious cases, there was decalcification and fracture of bone. Dislocations were also found to occur. For some strange reason, the complete syndrome was restricted to post-menopausal women, who had had several pregnancies. On investigation it was found that a local mine – the Kamioke zinc-cadmium-lead mine – released its effluents (containing cadmium) in the local Jintzu river. The water from this river was used both for drinking as well as for irrigating the local paddy fields. Thus cadmium found its way in the rice grown there as well. Cadmium ingested through intake of water as well as rice caused chronic cadmium poisoning, which was responsible for this syndrome. For the osteomalacia, undernutrition (common in post-war Japan) was also thought to be a factor."

"So now it is becoming clear that somebody mixed Cadmium salts in Kanta’s drinks. Tell me has Cadmium been used for murder before?"

"Not many times, but I do remember a case which was even reported in The Yorkshire Post of July 23, 1981. In this case two youths aged 14 and 15 administered cadmium chloride mixed in an orange drink to eleven children. They suffered from sickness and blurred vision, but fortunately no one died. The younger boy had strong political views and intended to poison his opponents. They had stolen the chemical from the Humberside Education Authority."

"Doctor, you have already told me the symptoms one experiences when one ingests the poison. What happens when one inhales Cadmium fumes?"

"Tarun, the initial symptoms and signs are sensation of constriction around the throat, a nasty taste in the mouth, irritation of the upper respiratory tract manifested by troublesome cough and redenning of the eyes. After a latent period of about one to two hours grave respiratory symptoms develop rapidly. Signs of pulmonary oedema (a technical name of a condition in which lungs are water logged) are also seen. The prominent respiratory symptoms are difficulty in respiration, pain in the chest, malaise, shivering and profuse sweating."

"Has Cadmium been administered in some other way also?"

"Tarun, I know of an interesting case of poisoning by intravenous injection which occurred in Japan. The patient had to be given an injection of calcium bromide, but by a rare accident, an injection of cadmium chloride was given. I may tell you that when Cadmium is given as a poison, the person usually dies in 24 hours, although death may be delayed for 7 to 14 days. If death occurs within 24 hours, the cause of death is shock due to loss of fluids. If the death is delayed, the cause is likely to be acute kidney failure or cardiopulmonary depression (depression of heart and lungs)."

"Doctor, you have certainly made most interesting conclusions. Now how are you going to conclusively prove that Kanta was given Cadmium?"

"Tarun, I have taken out Kanta’s internal organs, and have tested them for Cadmium. They have all given positive tests for Cadmium. Since it is not a normal body constitutent, it is clear that Cadmium has been given to her by someone. Following this I told police the whole story, and they investigated the death further. But this time they had murder in their minds, so they investigated more deeply. They found out that Sohan had been spurned in love by Kanta, and he wanted to take revenge. He stole some Cadmium Chloride from the chemistry lab, and then invited Kanta to his house. Although Kanta had spurned his love offer, she did not say no to his party as she wanted to continue a clean friendship with him. Moreover he told her that some other friends were coming over too. So there was nothing to be afraid of. When she and other friends arrived at Sohan’s house, he offered them cold drinks, and in the cold drink of Kanta, he mixed Cadmium Chloride. He probably chose this poison as this is such an unusual poison, and he thought that he could get away with that. But he didn’t know that forensic science can catch even the most intelligent of criminals. So even all his knowledge of chemistry could not come to his rescue."

"Oh, how very clever of you doctor. If you had not made such an intelligent and logical deduction, Sohan could be roaming in free world today. Criminals like him are very dangerous and should be put behind bars. 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- Aluminium Phosphide. "