Kadmium – The Silent Threat Unveiled

It is like drugs, or in the Indian context, like guthka. By now almost everyone knows the deadly consequences of the regular use of these noxious substances, but those addicted to their use continue to use them, even help to propagate their use. It is exactly thus with cadmium and the Indian jewellery trade.

In the late sixties Indian goldsmiths “discovered” a magic alloy for the production of solders or gold brazing alloys. The addition of a little cadmium to their original 22k alloy lowered the melting point, increased flow, and made soldering easy. “Best of all (!)” as this wonder brazing material flowed, it gave itself up in the form of fumes, and the remaining joint consisted (or was assumed to consist) only of the original 22k alloy. Its use was considered a “trade secret”, but slowly the news spread to almost all manufacturers, first in the metros, then in the smaller towns.

The terrible effects of those fumes were unrecognised, and more and more goldsmiths learnt of the preparation and use of cadmium solders. In fact, a cachet was attached to “KDM” brazed jewellery, and customers were charged a premium for those pieces that were manufactured using these alloys. This cachet, incred¬ibly, still applies, and KDM jewellery is even now sold at a premium! Until the World Gold Council entered the fray with good publicity against the use of cadmium, my protests against cadmium were gener¬ally dismissed, at best as the voice of an overly active, even crackpot, imagination and at worst as blatant lies to promote the sale of Hilderbrand paste solders, which I represent in India. Later Christopher Corti and others strongly promoted the idea of using cadmium-free paste solders.Finally, the B.I.S. announced some years ago that the use of cadmium would be considered unacceptable for jewellery bearing its stamp. These were very positive developments, but sadly among the general mass of jewellery manufacturers, the use of cadmium has been actually increasing with alarming rapidity.

Something about the metal itself:

Cadmium is a soft, bluish silver metal, fusing at 321º C, and boiling at only 765º. It is very volatile, with a vapour pressure of 14.8 Pa (at melting point). In nature it is usually found with zinc. Till recently, it had extensive use in industry as a plating material, as a pigment, in photoelectric cells and in electrical battery cells.

Since 1960 its extreme toxicity has been increasingly recognised, and progressive countries have either totally banned it (with the exception of its use in battery cells) or highly regulated its use. In most places it is expressly forbidden to use it in any application that is likely to be incinerated (burned), or in which the earth or water are likely to be polluted, to even the slightest degree. Mostly, its use without extreme precaution is banned.

So what are the Effects of Cadmium on Humans?

Well, short-term and immedi¬ate effects are gastroenteric and pulmonary. Goldsmiths regularly report that their bowel functions are disturbed, but usually put this down to the general lack of sanitation. Coughs, sniffles and other breathing discomforts that begin when they first start using cadmium (usually when they join a large workshop, soon after coming to a bigger city) are similarly put down to the polluted atmosphere. More subtle are the effects on the nervous system. The mucous membranes, especially the nasal mucosa, receive the cadmium vapour enthusiastically. From there, supposedly through the same mechanism that transmits odours (the olfactory nerves), the central nervous system begins to feel the effects: a general malaise, a little hypertension, some depression, even a moderate to severe loss of libido. Their eyelids are also often inflamed. All these are attributed by the goldsmiths to the problems and pressures of the city or of their lifestyles. After some time, the artisan becomes habituated and these symptoms either stop, or are perceived to be a part of life. Meanwhile the lungs continue to transmit cadmium into the kidneys, this time through a different mechanism, the blood stream. The cadmium is filtered out by the kidneys, but unfortunately not ejected out of the body.

... and in the longer term? Long-term, there does not seem to be a single system that cannot be affected by cadmium. As with other heavy metal toxins, the kidneys are a major point of attack. Incipient kidney dysfunction starts with the accumulation of this metal. Some kidney stones may begin to form. Finally the kidneys fail. Bone calcium is leached or chelated out, partly by a related process, and there is definite evidence of damage to the en¬tire skeletal system. Indeed, the dreaded Japanese Itaiitai disease, a painful, irreversible and fatal bone degeneration, has been traced to the consumption of rice grown in cadmium-contaminated fields. Low levels of cadmium have been shown to affect serotonin levels in the brain. Learning abilities are impaired, and higher levels have caused motor difficulties in the larger muscles, especially in the legs. Even as long ago as in the seventies, when the subject had not been thoroughly researched, the standard text on neurotoxicology reported definite effects on the peripheral nerves. Obstructive lung diseases and pneumonia (sometimes fatal) are known to have been caused by cadmium, and some researchers put it as one of the chemicals with a positive link to lung cancer.

Cadmium has similarly been linked to prostate cancer, and the disruption of several enzyme systems. It does affect the testes, and has been linked with infertility. Cadmium accumulates in the placenta, but thankfully it has not yet been demonstrated that any significant amount is transmitted to the embryo. Some new research suggests that cadmium may be responsible for genetic damage. This is not proven as yet. But if it turns out to be true, then be aware that our mistakes might be causing future generations incalculable damage. And remember the term “future generations” does not merely refer to remote human societies but includes your own children and grandchildren!

How does it get into our bodies?

Worldwide, the classic method is smoking tobacco grown near or on polluted land. Tobacco seems to be a collector and concentrator for cadmium, as are mushrooms and cocoa. Also, it can be ingested through vegetables or produce grown close to factories that may once have used (or still may be using) cadmium-based processes. The ground water may be polluted. Or some factory processes might be emitting traces of it into the atmosphere.  It is well known that the most dangerous form of cadmium is in its vapour form, but this is exactly the way in which goldsmiths and even factory managers ingest it. One often hears that the factory is large and well ventilated, or that the artisans use the torch carefully, or that they will “soon” stop using cadmium, or some such but I am not at all reassured by these promises. I do not believe that “taking care not to overheat the joint” will prevent the creation and ingestion of toxic fumes. Remember the vapour point of 14.8 is at only 321º ! Molten cadmium vaporizes slowly from its very melting point, much as water slowly evaporates at room temperatures too. At only 721º C, it boils vigorously, just as water boils at 100º. The temperature of the solder at its melting point is usually much higher. After all, the very reason most Indian jewellers use cadmium is to burn it out!

It is unthinkable to most re¬searchers nowadays that goldsmiths may be vaporising it INCHES from their very noses, or INSIDE their own factories that they daily attend. The levels of exposure that are possible on a workbench are probably several orders of magnitude (thousands of times) higher than “safe” atmospheric levels. Even inside their air-conditioned offices, owners and managers are exposed to perhaps hundreds of times the “safe” level.

This Level of Exposure is Criminal

Cadmium may also find an entry-point through the skin by absorption from exposed solder joints, such as the bases of ear-posts or along the line of a chain. I have just returned from a trip to South India, and was shocked that even in very small towns ingots of cadmium are sold to make not only solder alloys, but also to add to plain casting alloys. A commercial master-alloy (pre-alloy) assayed by my client had a content of cadmium ranging from 5% to 8%+. A respected alloy manufacturer supplies this. Despite warnings, the factory continues its use.

So why don’t we all feel ill?

The short answer is, “We do!” As with ALL heavy metal poisoning, the deadliest effects are long-term, and are SO diverse that without a specific test for cadmium poisoning, the affected person does not know about them. However, even the short-term (or rather immediate) effects are daily complaints for the goldsmith. Loose bow¬els, irritated eyes, respiratory problems and, after a slightly longer exposure, decreased libido, are all regularly reported by the artisan. Even his doctor will seldom, if ever, make the connection with cadmium. It is pure poison and it is not easy to eject it out of the system and so remains within the body for long periods. In humans, its half-life is reckoned to be anywhere in the range of 15-40 years. In other words, once ingested in a form accepted by the body, it takes a minimum of 15 years before only half of the dose is out of the system. That is, if the system is not daily subjected to still more ingestion of cadmium.

But are not gold, silver, copper and zinc also heavy metals?

Yes, but they are not (except zinc) anywhere nearly as volatile as cadmium, and further, they are nowhere nearly as harmful, if at all. Gold and silver, in minute traces, are known to be beneficial for health. Both are used in very powerful medications. Silver is a known destroyer of many micro-organisms. Copper in traces is necessary for good health. It is a known preventive/curative for arthritis (many people wear copper bangles or drink water kept overnight in copper vessels, and demonstrate the benefits). Similarly, zinc too plays a role as a needed trace element (also thought to be good for retarding the progress of cataracts). However, whatever be the efficacy of the curative powers of these metals, the important fact is the body gets rid of these with relative ease, unlike cad¬mium, which remains around (in the body) for years, even decades. Not a single researcher has suggested any beneficial effect of cadmium on any part of the body. All of the above is not scare-mongering. Remember that the levels to which our karigars and managers, indeed everyone at the workplace from designer to delivery-boy, are exposed are way beyond any natural exposure yet imagined by the medical researchers. They are the levels to which laboratory animals might be exposed to prove a point. Our industry is unknowingly paying a terrible price for having fallen for the ease and facility of soldering with cadmium. I am deeply against official controls and needless legisla¬tion; but unless the industry wakes up and rids itself of this accursed metal, perhaps it will be time to take some public action. Unless leaders of our trade take interest in this matter, no change will take place. I dream of the day when customers will stop looking for the stamp, “KDM”, and look for jewel¬lery proudly stamped, “NON¬KDM”. CF, or cadmium free, has al-ready been the world standard for many years for gold and sil¬ver alloys and soldering/brazing systems. I also urge those of the medi¬cal profession who are in touch with goldsmiths to make testing for cadmium poisoning part of a routine check-up for artisans. They are sure to surprise themselves. I offer ALL my personal help in this project, if taken up by responsible medical research.