Cadmium's mechanism of toxicity

[Kathleen Anderson]

Several days ago the New York Times had a story about hundreds of tons of 
zinc sulfate imported from China for use in plant and animal fertilizers, 
which was determined to be "heavily" contaminated with cadmium. Not all of 
the contaminated ZnSO4 has yet been tracked, and this is not the first time 
this has happened, according to the article.

I am not a toxicologist, but this story piqued my curiosity about the 
mechanism of cadmium's toxicity, partly because all of the references 
I checked merely told of its being harmful to all cells, very harmful to 
liver and kidneys, and so forth. But what I'd like to know is how it does 
its dirty work? What aspect of cellular metabolism does it interfere with? 
Should I be searching out a toxicology text for this answer, and if so, 
can someone recommend something suitable for one with a non-focused 
general biology (with limited chemistry) background?

Thanks for any leads.

Kathleen