That's like saying you can handle a 6-pack of beer without getting drunk but another person will be wobbly after two beers.
"I've had 12 -15 of those Amalgam fillings in my mouth for 50 years. I have not one symptom of mercury toxicity.... I should be a bed-ridden on death's door victim, right??? THEY are selling us a bill of goods, and we're falling for it. [member #461]"
We all have different tolerances for various substances.
Furthermore some of us have been exposed to lead or other things that cause a much greater adverse effect when present along with mercury. Boyd Haley, former chair of the Chem Dept at the U of KY has done work on that subject. I'm sure his paper is available on the net. I previously quoted from it. http://health.groups.yahoo.com/group/frequent-dose-chelation/message/50190
There are plenty of reports from people who were nearly disabled with a long list of symptoms and got their life back from doing heavy metal detox. I'm not suggesting that most people have this problem, but for a few it is hugely helpful.
R Cartland is an engineer with Master's in Physics, not the type of guy to be fooled easily. He was nearly bed ridden by chronic fatigue, etc while just in his 30's. He recovered after Amalgam removal and detox. He reported his case--with the documentation you'd expect from an engineer--to the FDA back in 2010. He talks about it here. https://www.youtube.com/watch?v=wE_bjZ4kdJI
Dr Mark Hyman writes in one of his books that he went to ten other doctors before someone realized heavy metals were involved his very long list of disabling symptoms. That was when he was still a fairly young doctor. https://www.youtube.com/watch?v=mjnGWSyxWJ0