While I was doing a search I found this very interesting article. It's a little long and was not formatted in a continuous form so you'll have to click on the link to read it. It explains how it's easier for heavy metals to accumulate when we are deficient in certain minerals and it mentions which deficiencies allow which metals to build up. It also explains that when we are "sufficient" heavy metals will not deposit in our bodies, great to know, don't y'all think?
To entice you to go read the article here's a "spoiler":
Selenium deficiency = mercury
Zinc “ = lead or cadmium
iron “ = lead
calcium “ = lead
Also, I mentioned in another thread that silica seems to be able to chelate aluminum out of the body: http://curezone.com/forums/fm.asp?i=914548#i, and since it helps to fix calcium and grow hair back, among other cool benefits, it's worth considering. Hope this is helpful to all of you who, like me, want to help detoxify heavy metals without having to feel like c - - p while doing it (and it does make sense to fill in the "void" right away as "natures abhors a void" ).