Cobalt: The Most Deadly Element?

Cobalt may seem innocent, peacefully hidden near the center of the periodic table, but in reality this element, commonly known for the beautiful blue pigment it produces, is deadly.

The name cobalt is sinister in itself. It comes from the German word for the element, Kobold, which means “goblin” or “evil spirit.” German miners gave cobalt this name since mining cobalt was very dangerous. Mining any element is hazardous to some degree but cobalt is particularly nasty since a toxic gas (arsenic trioxide) often occurs with cobalt in nature

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Cobalt is still mined today, mainly for use in smartphones. No doubt modern miners there would agree that Kobold is a suitable name. Cobalt miners, often children, work in perilous conditions, risking permanent lung damage earning about a dollar a day. Cobalt is in high demand due to its value as a component of super alloys, metal alloys that resist rusting and retain their properties at high temperatures. Super alloys have a variety of uses including forming parts of electronics and jet engines.

Cobalt isn’t only dangerous to miners. Cobalt-60, a radioactive isotope of cobalt, could potentially wipe out the entire human race. Leo Szilard, a scientist who worked on the Manhattan Project, figured out that an explosion of a cobalt-60 dirty bomb would kill all life in the vicinity of the explosion once it exploded, and would continue killing all life that ventured in the area for about 90 years. A cobalt-60 dirty bomb kills with heat like a normal nuclear bomb, but it has a hidden weapon that keeps it deadly for decades: gamma radiation.

A plastic isotope container containing cobalt-60
image used under creative commons

Most radioactive elements emit gamma rays for a few days, but cobalt is special. It keeps emitting deadly gamma rays for decades. These gamma rays mix up the chromosomes in our white blood cells either killing them or giving them cancer, making us vulnerable to disease. Szilard estimated that if one tenth of an ounce of cobalt-60 was sprinkled over every square mile of earth, all of humankind would perish. Thankfully no one has attempted to make cobalt-60 nuclear weapons yet, as far as we know.

Cobalt-60, despite its dangers, can also be used to help humans. Its radioactive properties are used to treat cancer, preserve food through food irradiation, and produce powerful X-rays to see through metals.

These are modern uses of cobalt, but humans have been using non-radioactive isotopes of cobalt since ancient times. Back then, cobalt was mainly used for dye. The ancient Chinese used cobalt blue in their pottery glazes. The ancient Egyptians probably used cobalt too since a small glass object colored with cobalt was found in Pharaoh Tutankhamen’s tomb. In addition to producing pretty blue dye, cobalt is one of the three naturally occurring magnetic elements

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The alchemists used cobalt in their experiments, but they attributed its properties and beautiful blue color to copper or bismuth. It wasn’t until 1730 that Georg Brandt discovered cobalt to be a unique element making cobalt the first element discovered that the alchemists hadn’t already isolated and named.

Cobalt Blue
a public domain image

The earliest use of cobalt, long before Georg Brandt or even the ancient Chinese, is the element’s use in the human body. Cobalt is vital to human health as a trace metal. We need it to form enzymes and produce vitamin B-12. It’s kind of crazy that one isotope of cobalt could kill us all, but we need another to survive.

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