Discovery and Name
Cadmium was discovered in 1817. A number of German pharmacies were having trouble with their supply of calamine, an anti-itching medication. The chemical name for calamine is zinc oxide. The German chemist Friedrich Stromeyer examined the problematic calamine and determined that the medicine was not pure zinc oxide, but instead contained a new element. He gave the new element the name cadmium based on the Latin word cadmia, meaning calamine.
No significant amounts of pure cadmium ores have been discovered. Instead, cadmium is extracted as an impurity found in zinc ores and other minerals.
Health Effects
One of the worst known cases of cadmium poisoning is known as itai-itai or ouch-ouch disease. A large number of older women near the Kamioka mines in Japan developed sharp pain, kidney problems, and very brittle bones. The bones of victims of this disease are so fragile that a doctor snapped one woman's wrist while trying to take her pulse . The first cases were reported in 1912, but it was not until 1972 that cadmium pollution was recognized as the culprit and cleanup efforts began.
Other cases of cadmium poisoning have been reported when workers inhaled cadmium dust. Even small amounts of pure cadmium can be toxic. Industrial standards now provide many safety guidelines to minimize cadmium exposure for workers.
Uses
One of the first uses for cadmium was in paint. The bright, long-lasting colors cadmium red and cadmium yellow were popular with painters like Vincent Van Gogh, and are still available today. Cadmium was also widely used as a coating on steel to prevent rusting. Many items like drinking mugs were manufactured with cadmium linings. When the negative health effects of cadmium were recognized, it was replaced in many applications with other materials that are safer and require fewer safety precautions in the manufacturing process. Today, the largest use of cadmium is in rechargeable Ni-Cd batteries. The importance of recycling these batteries to prevent environmental contamination is now recognized. Cadmium compounds are also used for other applications, such as photocopiers and solar energy cells.
Lesson Summary
Cadmium is a versatile element. It is used in batteries, paints, protective coatings and many other applications. Cadmium was first discovered as an impurity in calamine medication. Cadmium many forms of cadmium are recognized as being highly toxic.
The Disappearing Spoon by Sam Kean describes itai-itai and other cases of chemical poisoning.
