Mercury only shows up high in hair analysis when you're in stage 3 poisoning. The vast majority of people are in stage 1 or 2 and a hair analysis on any of them will normally show low mercury because the body is absorbing it in order to keep blood levels low.

When you enter stage 3, mercury levels in the blood rise because the organs are no longer able to absorb mercury and you will be having serious symptoms at this point. Of course, this can be 10 to 50 years AFTER the amalgams were installed.

When searching for mercury toxicity, expecially when you're in stage 1 or stage 2, hair analysis must be interpreted properly to determine if mercury is in the body tissues. Here is an excellent book that describes exactly how to do this:

Hair Test Interpretation: Finding Hidden Toxicities