what are the dangerous heavy metals we hear about popping up in diets?
cadmium, mercury (same # of valence electrons as zinc)
aluminium (same # of valence electrons as boron)
lead (same # of valence electrons as silicon, carbon)
arsenic (same # of valence electrons as nitrogen, phosphorus)
(ed: + chromium (same # of valence electrons as molybdenum)?)
these observations are not trivial; the fact that these metals can be substituted for their non-metallic equivalents is a big part of the reason of why they're toxic, whereas this giant swath of other heavy metals just passes through us without us even noticing them. you've heard scientists talk about how life is just chemistry, and this is a good example of the limitations of that; the fact that life is just chemistry means it's subject to all kinds of error, which can both spur evolution and kill us, maybe even at the same time. it's humbling to realize how utterly helpless we are in the face of the chaos and randomness around us. i'm an atheist, but i fully realize the power of random error in the world we live in; it doesn't help to anthropomorphize it, or assign it moral characteristics, but it certainly helps to give it a little respect.
so, you could eat an apple with just a little bit of arsenic in it everyday for your whole life and not have it do anything to you, until the day that you get unlucky and die from it. repeatability is supposed to be the basis of science, but the laboratory is a pretty shifty concept, in truth.
it is true that looking at it this way is sort of facile - lead can also replace calcium, for example. this has to do with energy levels and i'm not posting a lecture on quantum chemistry, even if i like my lpi links. that's a familiar name, there's some trust there. but, lining these things up really demonstrates the importance of getting not just zinc & phosphorus, but also silicon and boron - as well as potassium, calcium & sulfur/selenium. it's not an antidote for actual poisoning and, of course, nobody consumes heavy metals on purpose, unless they're suicidal, but getting these non-metals in high quantities should at least act as a first line of defense against any metals that you accidentally consume by crowding them out from absorption.
and, don't pretend you're not consuming them, either.
'cause you are.