"Heavy Metals" . . . are they an "issue"?

So what exactly are "heavy metals" . . . and how can they affect us???
Well . . . this all goes hand in hand with everything we've been talking about.
You see . . . the term "heavy metal" . . . refers to any "metallic chemical" that has "high" density . . . and is "toxic" . . . in "low" concentration.
The same with "mold" . . . "high" density . . . that can be "toxic" . . . in "low" concentration.
Okay . . . so with that being said . . .
What are the 5 top "heavy metals" we need to be aware of???
Well . . . they would be . . .
Mercury
Lead
Chromium
Arsenic
And "CADMIUM" being the most dangerous
And what are the symptoms of these elements in the body???
Well . . . we would look for . . .
Fatigue
Headaches