To your first question, most people have levels of heavy metals in their system that are higher than they ought to be for several reasons 1) most everyone alive has received tons of vaccines and they didn't even set a date for removal of mercury until 1997 and still most of the vaccines don't have to have it totally removed until 2005. 2) Lots of people know that eating fish can help prevent cancer and heart disease and lower cholesterol, but most of the big fish that we eat contain lots of mercury from contamination (this is not conspiracy theory, but scientific finding). Most people are able to excrete heavy metals pretty well, but not everyone. Those that cannot excrete it or whose systems get so flooded with it that they are overwhelmed, suffer brain damage like alzheimer's, autism, autism spectrum disorders and other learning disabilities. There are a number of studies by independant researchers out there that show the links between brain damage/disorders and heavy metal levels. Naturopaths can test these levels using several methods, but the most common (also used by forensic pathologists) is hair sampling. The content of the hair follicle is measured. It can show not only levels of heavy metals excreted from the body, but also exposure period (like whether it was an isolated incident such as a single set of vaccines or prolonged like eating mercury containing fish 4 times a week for a year). In the years before mercury-preserved vaccination, the stats state an incidence of autism and alheimer's as being like 1 in 20, 000, but we now have a current rate of incidence of approx. 1 in 200. That high rate isn't even including the people who have autism spectrum disorders (which are like having varying degrees of milder autism - people who can function to some greater or lesser degree). I do think that the oceanic contamination also contributes to this number as well as other factors that I may not be aware of, but the stats I've seen are particularly regarding vaccines.To the second question, flu vaccines and other vaccines have contained and do still contain mercury as a preservative. I am currently trying to research whether there are other medicines or medical therapies that use mercury as a preservative (like the saline and heparin that are used in our IVs - they typically contain a preservative, but I do not know from what origin)Please don't get me wrong, I'm not saying we should all boycott vaccination, but I am concerned about getting all the facts and making educated decisions. I plan to be around as long as I can manage it and if my body is still working, I want my mind to work too.