Friday, May 28, 2010


I was working out of my office yesterday, in a building that is basically a line of industrial workshops. I was doing some necessary but messy work and when I was done I swept out my workspace. The floor was dusty and by sweeping I put that dust into the air and no doubt breathed some of it in. It turns out that in one of the workshops at the end of the building is contaminated with cadmium. I doubt that sweeping the floor at the other end of the building exposed me to much, but I have worked with cadmium paints in the past so I did some looking into its toxicity.

Discovered in the 1800's, cadmium is a metal that has a bluish-silver look to it. It is soft and easily manipulated and can be a byproduct of zinc production. Since our bodies have no use for this metal, it is toxic to us even at low concentrations. To me the scariest part is that cadmium bioaccumulates – there has been reports of cadmium poisoning from crops downstream of mines. Ingesting it over a long period of time can result in kidney disease and various types of cancer – but inhaling cadmium fumes can be fatal relatively quickly.

Even with its scary side, cadmium is interesting stuff. I first encountered cadmium as a pigment component; it makes brightly coloured yellows, oranges and reds that last for centuries without losing their original bright hue. These shades replaced older, not light-fast pigments such as vermilion (mercury sulfide). Cadmium has also been used as a corrosion-resistant coating for steel and as a stabilizing compound in plastics.

Because of its toxicity, cadmium use is in decline. There are now non-toxic replacements for the cadmium pigments, it has been phased out of plastics and many of its other uses. Currently, most of the cadmium produced goes into nickel-cadmium batteries, which leaves a worry of how these batteries are disposed of.

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