"after doing LOADS of research, different labs are better than others and use different procedures to conduct a test. hair analysis tests can be a very accurate way to determine the amount of heavy metals in tissues. "

I don't see how. Hair analysis might show how much mercury is excreted through the hair, but not how much is excreted in other ways. It will never show how much is mercury present in the body. The percentage present that is excreted through the hair can vary tremendously. The results of hair analyses might even vary quite a bit depending on how often hair is washed and what shampoo, conditioner, and other chemicals are used on the hair.