REPLY: This is an arena fraught with methodology problems. Hair is unreliable, as demonstrated by split tests getting widely different results; meaning that a sample of hair is submitted under two or three different names results in three different reports. The provocation tests, where a chelating agent like DMSA is administered and urine is collected for 6 hours invariably produces artificially high numbers. By that I mean that the chelating agent only accelerates the removal of molecules that the body was in the process of removing. Since chelating agents act primarily in the first 3 or 4 hours, the 6 hour collection is another factor creating artificially high numbers. The 24 hour unprovoked urine test remains as the only reliable guide because there are standard reference ranges that are used throughout the world.
I will also point out that, unless there is a clear exposure event or events (such as a child eating lead-based paint, or an adult working with occupational exposure to mercury) the ballyhoo about heavy metal poisoning often borders on fear-mongering. Good epidemiological studies show that the general population has urine-mercury levels below 10 micrograms/liter, with most people between zero and 5, and excretion is an ongoing process. I eat 8 to 10 servings of fish a week, meaning that I should have elevated mercury levels, when in fact – a 24 hour urine test put me at 6.5 mcg/L. I can only surmise that my detox capabilities are adequate. I’m sure that a provocation test would have produced three to five times as much mercury, and I would have been advised to undergo an expensive round (or two) of chelation therapy… but for what?
Hope this helps!