This free article as well as this article do a good job highlighting the carcinogenic effects of Cadmium and the mechanisms by which they occur. However, my question is why is Cadmium so carcinogenic compared to other heavy metals? What chemical property of Cadmium makes it more prone to these carcinogenic actions than, say, Mercury or Lead or some other heavy metal?
To give a more concrete example, the recommended safe levels of Lead in water is 50 ppb, whereas for Cadmium, it is 5 ppb. Why is there such a stark difference in their health effects?