CADMIUM, THE DRAGON'S TEETH

Doctors concerned with occupational diseases have long known that cadmium is poisonous. Pharmacologists, also, have known that small closes lead to bizarre effects in animals. At the turn of the century, cadmium was a rather rare metal nearly always associated with zinc, little used industrially, a metallic curiosity with a bluish-white luster quite impervious to corrosion, like tin.

World War I brought enormous demands for tinned food and a shortage of tin, so that a substitute was needed. Cadmium was ideal though expensive, but its possible toxicity in foods required investigation. In the early twenties, a deluge of literature appeared showing that cadmium was not suitable for coating food containers; small amounts dissolved by acid foods and drinks made animals and people acutely ill.

The reader may remember the old Greek myth about Europa, daughter of the King of Phoenicia, who was abducted by a traveling bull and from whom Europe gets it name. Cadmus, her brother, was sent by his father to find her. Cadmus consulted the Delphic oracle and was commanded to give up the search, for Zeus had the lady in Crete for his own amorous purposes. Instead, he was told to follow a certain traveling cow and to build a town where the cow sank down exhausted. He chased the cow through two countries and built the citadel of Thebes where she sank. Cadmus then sent some people to fetch water from the well of Ares, which was guarded by an un-friendly dragon. The dragon slew them, as that was his job. Cadmus killed the dragon, and on the advice of Athena, ploughed a field and sowed the dragon's teeth. A regiment of fully armed fighting men sprang from the ground, charged, and turned on each other until all but five were killed. These five were the first Thebans, the Sparti, or sown-men.

Cadmium has somewhat the same properties as the dragon's teeth. It looks innocuous but it has a vast potential to poison. Unlike the sown-men, it is not recognizable as an enemy, acting subtly and under- cover, mimicking diseases in man for which other causes have been proposed, accumulating in the body slowly until "the threshold of resistance is overcome, then striking. This subtle property was not recognized until recently.

With the loss of Malayan tin in World War 11, cadmium was again considered as a substitute for tin cans. As a result, another spate of papers appeared in the middle forties again showing its animal toxicity. The memory of Science is often short.

In spite of its toxicity, cadmium was used to coat ice trays in electric refrigerators. Some people like to make lime or lemon sherbets by freezing the mixes in ice trays. The acid will dissolve some cadmium, and in the mid-thirties there were several cases of acute cadmium poisoning with a few deaths from this source. Dr. Thomas Arthur Gonzales, then assistant medical examiner of New York City, tracked it down, and cadmium-coated ice trays were banned-in New York. (But not everywhere. In the late fifties, I discovered four such trays in my General Electric refrigerator-and banned them.)

Dr. Gonzales, being a thorough scientist, analyzed the organs of his cadmium victims by the method then available. He found the kidneys loaded with cadmium-but so were the kidneys of people dying of other causes. He gave up the study, and it was not until 1953 that Dr. Isabel H. Tipton found much-but varying-amounts of cadmium in kidneys of all the adult Americans she examined, but little or none in babies' kidneys, thus starting us on our worldwide search for cadmium and its sources.

Cadmium became well established as an anticorrosive plating on metal parts during World Way 11. It was virtually essential for aircraft exposed to salt spray, and hardened aluminum nuts, bolts, cylinders, small parts, and valves showed the characteristic pale yellow color of cadmium plating. In 1944 1 took a hundred gravity-operated valves, part of automatic equipment for pilots' anti-blackout suits, on an aircraft carrier far into the Pacific Ocean for three weeks. They lasted two weeks under operating conditions. When similar valves were anodized with cadmium, not a single one out of some fifty thousand failed from corrosion. Nor has one failed since.

Thus, cadmium is replacing zinc as a plating on metal. Some 16,000 tons are used yearly and consumption rises every year. In Now York City alone, there are 152 small companies engaged in cadmium plating. Metal parts are put into an electrolytic bath containing cadmium salts, plated, and then removed and washed off with fresh water. The drippings go down the drain. The cadmium enters the city’s sewage treatment plants, collects, and in time poisons the bacteria digesting sewage and garbage. The treatment plant then has to shut down for several months, in the interim discharging raw sewage into the rivers and the harbor. Not only is raw sewage an unpleasant pollutant, but the cadmium precipitates in salt water to the bottom mud, where it can enter the food chain. just a little cadmium, a half to one part per million in water, is toxic to most bacteria tested.

Two lawsuits have been brought by the U.S. Department of justice. One is against the City of New York, the mayor, his environmental protection administrator, his water commissioner, and two electroplaters as representatives of a class of about 200 firms for polluting federal waterways with cadmium, other heavy metals, and toxic substances. The second is against the State of New Jersey and its many towns and cities discharging into the Hudson River and New York Harbor. These suits demand compliance with city, state, and federal regulations on pollution of the aquatic environment with antimony, arsenic, barium, boron, bromine, cadmium, chromium, copper, fluoride, gold, iron, lead, manganese, magnesium, mercury, molybdenum, nickel, rhodium, selenium, silver, thallium, titanium, tungsten, vanadium, and zinc (see Table VII-1).

If the Department of justice wins, and discharge of cadmium into sewers virtually ceases, it will still be too late for the fish in the Hudson River. The Trace Element Laboratory and the Environmental Protection Agency have evidence that over half the fish in the Hudson River are unsafe to eat regularly because of contamination with cadmium.

One cannot predict how much cadmium is in fish by measuring it in water. The Hudson River has very little cadmium dissolved in it, a few (3-6) parts per billion, but its fish have a good deal. Four Alabama rivers had 6, 12, 65, and 90 parts per billion cadmium, respectively; about the same amount of cadmium, very little, was found in fish from these rivers (Table VII-2). Compare these Alabama fish with Hudson River fish and the difference becomes obvious. The Hudson River cadmium is in the mud and the food chain; in the Alabama rivers cadmium is in the water and in the mud at the source but not downstream. It is cadmium in mud, not in water, that we must worry about.

In 1972, a lawsuit by the Department of justice against the Marathon Battery Company and Sonotone Corporation was won by consent of the defendants. These companies made cadmium-nickel batteries for warplanes, hearing aids, power tools, and electric shavers and were discharging wastes into Foundry Cove on the Hudson River. Mr. David M. Seymour, a worker for the Audubon Society, and Robert H. Boyle, a free-lance writer on sport fishing, were walking by the cove and noticed that the mud had a greenish gray color, like pea soup. They sent us some of the mud and Alexis P. Nason, our laboratory analyst, found that it contained over 16% cadmium and 22% nickel. There were an estimated 25 tons of cadmium and 32 tons of nickel in the cove, which at $2.00 and 80 cents a pound, respectively, were worth about $150,000. They asked me what to do. "Mine it" I answered. But they didn't. They began catching fish and sending them to us until Mr. Nason was piled high with work.

About then, Senator Philip S. Hart entered the picture, and his people persuaded us to analyze the 44 Alabama fish listed in the table. Our freezers were full of fish. Mr. Nason analyzed them and said, "No more. The law of diminishing returns is now operative." We had learned most of what we wanted-and needed-to know: cadmium in river water was not necessarily reflected in its fish.

The Department of justice then entered the fray, and persuaded the EPA to do the analyses. Which they did, on everything. It added little to the case, except to show that most Hudson River fish were contaminated, as was the food chain (which we knew).

In December 1971 our laboratory was turned into a miniature courtroom, with lawyers for the prosecution and defense, federal court reporter, oaths, and all the works but a judge. Transcription of my testimony was three inches thick, and so garbled that I never got around to correcting it. But it was enough. The next June the EPA announced the verdict: we, who helped discover the stuff, did not even get honorable mention. But the defendants removed most of the cadmium and nickel from Foundry Cove, thus preventing a hundred years of further contamination of the Hudson River. Fortunately, there is yet no cadmium lobby or propaganda institute.

The Hudson River is a local and regional problem. So is the Jintzu River in Japan. A large lead and zinc smelter was discharging its tailings where they were washed by river and rainwater. The river was used for irrigation and drinking by people living downstream. Cadmium and lead entered rice and wheat crops, fish, and people. They accumulated. After many years, a disease named itai-itai --ouch-ouch--appeared in women past the menopause. Calcium was lost from bones, and they fractured easily. Kidneys were badly damaged. Deformities were severe. Many died. The victims' organs were loaded with cadmium and lead. Even their bones had much cadmium, and cadmium does not usually enter bone. It will probably take a hundred years for that soil and river bottom to cleanse itself of lead and cadmium.

All that happened from a zinc smelter. Cadmium is constantly present in zinc, even the purest. The U.S. Bureau of Standards' standard zinc slab has 0.53% cadmium. The zinc used for galvanizing iron--tin roofs, pails, water storage tanks, iron pipes, gutters, water-softening tanks, maple-sap buckets, cauldrons, barbed wire, chicken fences, wire fences, animal cages, nails, and a host of other articles of iron or steel--is far from pure, generally being the cheapest grade, which contains even more cadmium. Impure zinc can contain up to 2%.

Whenever a slightly acid liquid comes in contact for a time with galvanized metal it dissolves some zinc and cadmium. Rainwater is slightly acid from the dissolved carbon dioxide in the air. Falling on a tin roof, collected by a gutter, stored in a galvanized iron cistern, rainwater will contain zinc and cadmium, for it is slightly corrosive. Soft water is also corrosive, and when it stands overnight in galvanized iron pipes, it dissolves zinc and cadmium. When you draw water for your morning coffee before flushing the pipes by running the water, the cadmium is in the coffee. Most of the galvanized iron plumbing in the old houses of our town has been replaced with copper, for our soft acid water has corroded the pipes. First the zinc and cadmium plating goes, then the iron, which makes the water rusty, and then a leak springs and there is a hurried call to the plumber. Soft water also corrodes copper from pipes-bluish green stains on the toilet bowl and the bath tub are characteristic. Hard water is usually not corrosive. Hot water is much more corrosive than cold.

A number of cases of so-called zinc poisoning have been caused by drinking lemonade which has stood for several hours in galvanized pails, cauldrons, or washtubs. Actually they were due to cadmium poisoning, for zinc is not poisonous except in huge doses. Zinc is necessary for all living things, and plants and animals grow poorly or die when there is not enough zinc in their environments. In zinc-deficient soil, a half dozen galvanized nails driven into the trunk of a fruit tree make the difference between health and disease; a string of barbed wire can make healthy crops grow near the fence. Zinc-deficient chickens can get enough zinc by pecking at the wire on their cages or pens. So can rats by licking galvanized wire. But they also get the cadmium.

The human body contains about 2.2 grams of zinc, and there are mechanisms which keep this amount constant throughout life, unless the diet is low in zinc. The body contains a variable amount of cadmium, normally 30 milligrams in Western society, as little as 10 milligrams or less in certain African nations, as much as 50 or 60 milligrams in some people, especially the Japanese, who have more than the Europeans. Zinc does not accumulate. Cadmium, once in the body, stays, probably for life, in the kidneys, the liver, and the blood vessels. As little as 2 micrograms daily absorbed and retained results in a body burden of 30 milligrams in 40 years. Cadmium displaces zinc but does not act beneficially like zinc; quite the opposite. The human kidney contains 8 to 10 times as much cadmium as do the kidneys of any other mammal, except those pets exposed as we are.

Where does the cadmium come from? The air of some cities contains cadmium from fumes spewed out by zinc smelters and refiners and copper smelters. More than 2,000,000 lb (about 1,000,000 kg) are released into the air space of U. S. cities annually from this source alone. An additional 2,300,000 lb went up the chimney in 1968 from the recovery of scrap metal, and another 300,000 lb from incinerators. World consumption is 31 million lb, of which the U. S. uses 12 to 13 million lb. When we swallow cadmium, only a small amount is absorbed into the body from the gut, perhaps 10%, most of which is excreted in the urine. When we breathe cadmium, we retain about half of it, absorbing it from the lungs. A pack of cigarettes contains 16-24 micrograms of cadmium, and a smoker can contaminate a whole roomful of people. 

Rubber tires, plastics, pigments, plated ware, alloys, insecticides, and solders are some of the things containing cadmium. Some foods have a lot of cadmium, relatively: oysters, foods contaminated in the processing, some instant coffees and teas, some canned foods, kidneys of pigs given cadmium as a worm killer, gelatin and fish dried on chicken wire, some cola drinks. We used to get it from dental fillings, but we don't any more. Pigments can be a source, for cadmium yellow and cadmium red are fast colors; some French lipsticks have it. A necklace of candy "Luv" beads made in Hong Kong was colored with cadmium; it made one little girl sick for over a year and poisoned her brother for a short time.

Cadmium is so ubiquitous in our civilization that it is very difficult to avoid it. Our laboratory developed a diet for rats and mice which is very low in cadmium, so low in fact, that it does not accumulate in their bodies over a lifetime. But we have to keep our animals in a metal-free laboratory on a remote Vermont hilltop, give them absolutely pure water, and take extensive precautions to avoid contamination. All commercial diets contain too much cadmium for our use.

What is the price we pay for environmental cadmium? High blood pressure is one. And a major one. The earliest sign of subtle cadmium toxicity is elevation of the blood pressure (Table VII-3). The usual upper limit of normal for rats' blood pressure is about 140 millimeters of mercury. With only a trace of cadmium in the diet and with only a trace in the kidneys and liver, it was a bit over 80. When rats were fed a commercial diet containing cadmium and some deposited in their kidneys, their blood pressure was about 110. Not high, but higher. When cadmium was given in drinking water and there was much in the kidneys, liver, and blood vessels, the rats bad high blood pressure, with large hearts, thickening of the small arteries of their kidneys, and, in some cases, heart attacks and hemorrhages. They also showed hardening of the arteries.

High blood pressure from cadmium has now been produced in rats, rabbits, and dogs. It is not severe, usually, but is the spitting image in all respects of the kind 23 million Americans have, which promotes heart attacks and strokes. When we look at human kidneys, we find that people who died with high blood pressure had either more cadmium or less zinc in their kidneys than did people who died of other causes. Cadmium had displaced zinc and slightly poisoned some zinc system that controlled blood pressure.

We played a trick on Nature. The laboratory developed a drug which contained zinc but which would chelate--bind, or grab--cadmium where it met cadmium and drop zinc in its place. High blood pressure in rats was cured very quickly; some of the cadmium was removed and some zinc put back. In people, this drug has lowered blood pressure for long periods of time, removing a little cadmium from the right places, probably the blood vessels.

In essence, we reproduced a common human disease in animals by using a common toxic metal, cadmium, cured it by removing the metal, found a similar situation in man, and relieved it in the same way. Although there is little more to do except clean up a few minor pieces of the picture puzzle, it will take ten to fifteen years before the medical profession will accept this novel idea, in spite of the fact that our work has been confirmed by others.

Emphysema of the lung is a nasty disease. The little air sacs of the lungs rupture, making larger ones. Breathing becomes labored. High blood pressure in the circulation of the lung appears, straining the heart and leading to heart failure. Emphysema patients also have more cadmium in their kidneys and livers than do well people. Cigarette smoke contains cadmium, and it is tempting to guess that cadmium absorbed directly by the lungs initiates high blood pressure there. Emphysema is common in cadmium workers. Our drug might be of value in treating emphysema.

When fed to breeding rats and mice, cadmium causes severe congenital abnormalities, to such extent that the strain dies out. When injected into pregnant rats, it produces toxemia of pregnancy, and into pregnant hamsters, congenital abnormalities in the offspring. Injection is not a fair way to test anything we eat, drink, or breathe, but it serves to show bizarre toxic effects.

Did anyone ever think of injecting waste water from washing machines and dirty dishes into pregnant women? Of course not. Yet that was what the Environmental Protection Agency and the Public Health Service implied when they banned NTA last year.

NTA--nitrilotriacetic acid--like the polyphosphate detergents, is a chelating agent, binding metals. That is its virtue. NTA was allowed as a good substitute for phosphates, which are highly nutritious to plants and cause overgrowth of algae in stagnant lakes, choking off fish life. Some 100 to 125 million tons of NTA were made annually as a substitute. NTA is rapidly biodegradable by oxygen-dependent bacteria, a distinct advantage over phosphates.

Some experiments were done at the National Institute of Environmental Health Sciences--rather rapid ones, I suspect from the data--in which NTA was injected into pregnant rats. No effect. Cadmium and methyl mercury were also injected. No effect. Combined with NTA, cadmium and mercury were both lethal to fetuses and mothers.

The idea is that cadmium and methyl mercury are common water pollutants. NTA gets into the water from drains and combines with methyl mercury and cadmium. Pregnant women drink the water somewhere else and get dead babies. Synergism. The NTA allows the metals to get into the body and pass through the placenta into the fetus.

To anyone with a knowledge of trace metals, there are several glaring flaws in this argument:

1. Although methyl mercury probably occurs in waters where it has been dumped, it has never been demonstrated to exist as such in any water, and it is probably rare in the United States. Regular mercury is found in concentrations of less than 5 parts per billion such small amounts are harmless, NTA or not (Table VII-1).

2. There is a little extra cadmium in some rivers, but most waters have less than 10 ppb, too little to harm a fetus.

3. No one has demonstrated that NTA by mouth increases the absorption of cadmium or methyl mercury by the intestines. Indications are that it doesn't, for most other metal chelates are poorly absorbed-the molecule is too big.

4. Large doses of cadmium and methyl mercury injected into pregnant rats did nothing, although much smaller doses by mouth are bad both for the young and the mothers, as several people have discovered. There was something fishy about the NTA experiments.

Two Swedish technicians came all the way to the Virgin Islands to consult about NTA. They were worried about the data. On critical examination they did not stand up. Neither did the experiments. The Swedes went home satisfied to continue the use of NTA.

The following year the Public Health Service backtracked quietly and lifted the ban on NTA, which is now clean as a hound's tooth, although slightly tarnished in reputation. So it goes.

One of the subtle effects of this product of the dragon's teeth is that no other measurable function of the body is altered, other than the level of blood pressure and what goes with it. The patient does not know that a function of his kidneys detectable only by sophisticated techniques is changed, nor does he feel the difference in his blood pressure, except under anger or anxiety, when he may flush or his heart may pound. Yet his heart works harder with each beat, day and often night, gradually enlarging; the very small arteries of his kidneys constrict in an attempt to protect the delicate capillaries which filter his blood to make urine, and both show signs of strain; he already has a serious blood vessel disease, arteriosclerosis, and the heightened blood pressure increases its progression and makes it worse, both in his large arteries, which do not matter too much, and in the smaller ones of his heart and brain. The process, a vicious cycle, goes on inexorably, until one day in his middle age, there is a sudden accident. An artery in his heart is narrowed to the point where it supplies insufficient blood for the needs of that part of the heart, and he feels the severe pain of angina pectoris. Or the artery plugs, and he has a heart attack, or coronary occlusion. Or, later in life, the same thing happens to an artery in his brain, and he has a stroke or thrombosis. Or an artery in his brain ruptures, and he has a cerebral hemorrhage. Something like that kills over half the population of our country.

High blood pressure can now be treated with modern drugs and is often reversible, unless it has gone too far. When well-treated, its serious consequences, heart failure and hemorrhage, largely disappear. Unfortunately, it is not as well treated as it should be, even though the death rate from hypertensive heart disease is one quarter of what it was 20 years ago. If we could remove the cadmium from blood vessels, replacing it with needed zinc, regular treatment with drugs could become unnecessary, except at long intervals.

The amount of cadmium we take into our bodies seems to depend on the amount of zinc we also absorb; the more zinc, the less cadmium. We can speculate with reasonable assurance that plenty of zinc may displace a little cadmium in the tissues. We know that animals deprived of cadmium have less zinc in their bodies than do animals fed cadmium, which have twice as much, although they seem healthy. Cadmium demands zinc. Today, with the wide use of refined flour, sugar, and fats, we are not getting enough zinc for our needs, especially if cadmium is around in our food, water, and air. Many Americans, especially teenagers and the aged, have measurable zinc deficiencies.

A major breakthrough in the treatment of poor circulation of the legs resulting from narrowing of the arteries is the use of large amounts of zinc by mouth. Pain ceases, normal color returns, exercise tolerance improves, ulcers and gangrene heal, and the affliction is cured. We don't believe that zinc reverses the arteriosclerosis of the vessels-though it may. Rather we speculate that zinc displaces cadmium and reverses the spasm induced by it in minor arteries. Zinc also works in angina pectoris.

When an artery is narrowed at one point, the small arteries it supplies downstream become highly sensitive to material in the blood which may normally constrict them a little. The end result is marked loss of blood flow. Zinc prevents that sensitivity.

Zinc by mouth is also of value in loss of sense of smell, which can be caused by cadmium, but cause and effect have been established only in cadmium workers. Zinc increases healing of wounds, for it is necessary for the growth of cells. I have also seen it improve tolerance for alcohol, and it has been used with some success in cirrhosis of the liver.

The skeptical reader may ask "Haven't we always bad high blood pressure, before cadmium was introduced into the environment?" We have, associated with kidney diseases, at least since 1693, but it has been nowhere near as prevalent as it is now. In certain parts of the world, for example, Burundi, Africa, it occurs only when the kidneys are diseased. The moderate and extremely frequent type seen in this country is only found in civilized societies or in places where there is obvious exposure to cadmium in water--certain islands of the West Indies, where rainwater is collected on galvanized roofs and stored in galvanized cisterns, for example.

That hypertension is mainly an environmental disease, although it may have a hereditary background, becomes clear when one examines the whole picture. We do not have space for more than the highlights. The Negro race is supposed to be very susceptible to hypertension; in this country, it is, with three or four times as many deaths as among whites. Hypertension is common in West Africa, but not among Central African Negroes. The rate for Negroes is equal to the white incidence in the Virgin Islands but twice as high as the rate for whites in St. Kitts. In other words, the incidence in Negroes varies from negligible to very high depending on the area. The incidence of hypertensive deaths in white people varies from city to city in the U.S. by as much as four times. From country to country it varies by as much as ten times. It is very high in Japan and very low in Thailand. In 94 cities of the United States, the death rate from heart attacks varies directly according to the corrosiveness of finished municipal water (see Table VII-4); in Japan, the death rate from cerebral hemorrhage varies according to the corrosiveness of river water. Death rates from heart diseases vary according to water quality in Britain, Canada, Sweden, the Netherlands, and South America. It is the pipes, and probably cadmium in the pipes, which are responsible.

There is everywhere a marked difference in death rates from heart disease in backward countries between the lowest class and the lower middle class. The first thing a poor family does when it establishes some measure of economic solidarity is to move into a house with running water. There they begin to have heart attacks. Doctors argue that such people eat more fat, or sugar, or what-not, thus accounting for heart disease. Pipes seem more logical villains.

What can we do about the situation with this subtle, accumulative poison, a clear and present hazard to health? First, we can prevent its emission into the air. Whenever zinc is burned or melted there will be cadmium. Incineration is a major source: burning of automobile tires, red and yellow plastic bags, plastic products, paints, discarded automobiles, discarded airplanes, and the parts thereof. Cadmium pollution can be abated by prevention of air pollution with zinc (Table VII-5).

Second, we can prevent its solution into water--along with lead--by providing municipal waters that are not corrosive. It is not difficult. Almost all municipalities treat their water, but not for corrosiveness.

Third, we can begin to control cadmium entering food and drinks by careful monitoring-by prevention of dumping into rivers and estuaries, by restrictions on its use in food containers--in other words, as we try to control any poison. In Table VU-5 are some examples of foods containing cadmium. Others with more than 1 ppm are smoked kippers, canned anchovies, lamb chops, chicken, olive oil, instant coffees and teas, tea leaves, and caffeine-free coffee; some with more than 0.5 ppm are all seafood, meats, wheat gluten (cadmium goes with the gluten in grains), oils and fats, margarine, Purina Chow, molasses, honey, black pepper, cocoa, butter, and nonfat dried milk, most of them processed.

Although most of the cadmium we encounter comes from food, only small amounts are absorbed by the intestinal tract, and even those are lessened when the diet contains plenty of zinc. It is highly likely that the largest part of the cadmium in our bodies comes from air- from tobacco smoke, polluted air, and dusts-for most of the cadmium inhaled is absorbed directly from the lungs into the body. As little as 1 mcg per day retained would build up a body burden of 14.6 mg in 40 years, over a third of the average amount, 38 mg, in all tissues. A pack of cigarettes contains 20 mcg, of which 10 mcg are absorbed from smoke. So it is easy to get enough cadmium to cause illness.

The pattern of storage of cadmium in the body differs according to the route of entry (Table VII-6). Workers exposed to heavy dusts, as in cadmium-nickel battery plants, had large amounts in their livers, with ratios of concentrations in liver to kidneys usually greater than 1.0. Total amounts stored, of course, were much larger, for the average liver weighs six times as much as the kidneys. Persons with high blood pressure had twice as much cadmium in their kidneys as did normal people, but no more in their livers. Japanese with ouch-ouch disease got their cadmium by mouth, and they actually had less than did those exposed to dusts in factories. The total amount of cadmium stored in the livers and kidneys of exposed workers was nearly 350 mg, the total in those organs of hypertensive persons was only 20 mg, and the total in normal persons was about 12 mg. Therefore, a little cadmium goes a long way.

Cadmium is a perfect example of an accumulative abnormal and subtly toxic trace metal in the environment causing widespread and serious human diseases, most of which are fatal. As such, cadmium is the worst of the bad actors among the metals.