ALA increases copper excretion in the urine and to some extent intestinal secretions, but inhibits copper excretion in the bile. Copper excretion is as follows in terms of percentages:

Bile - 80%
Intestinal Secretions - %16
Urine - 4%

So ALA can speed up excretion of copper by the channels that get rid of 20% of it, but can also slow or stop excretion of copper by the channel that gets rid 80% of it. The net effect is that for a normal individual, ALA will tend to raise copper levels in the body. If you were never to take a break from ALA chelation, it could raise copper to dangerous levels.