ALA is not dangerous in and of itself. It is an antioxidant, naturally occuring in different foods. And somebody who does not have mercury or other metal toxicity (that it has an affinity to), would be ok to take it as a general supplement/antioxidant and would not have to consider dosing times etc.

When it is taken straight to be used as a chelator, it is a powerful one for mercury (organ mercury).

Because of this, it must be used appropriately, as it is able to cross the blood brain barrier so mercury can come out of the brain. If one uses ALA too early on when the blood/body levels are still too high, there is the risk that the ALA will take some of that mercury with it as it crosses into the brain.

The other risk of course is not taking it every 3 hours around the clock. The regular dosing is essential to reduce redistribution of mercury and ensure the blood levels of the chelator (ALA in this case) remains stable and consistent, so the movement and removal of mercury is the same.