the only toxin one would have to worry much about reabsorbing would be mercury. freeing it up allows it to methylate and that is the most toxic form. but i am not even sure the oil frees up mercury.
i played with this notion and found no problem with loading up the oil. in fact, i have pulled for 20 minutes, and then again and again until i started getting lighter pulls. i always got relief and never felt toxed by the experience. i was so sensitive ot any toxins i couldnt even be in traffic without getting downright ill from the fumes. i know toxic. i dont think this is a concern. and i generally agree with andreas. i just think he is being overly cautious. he is also lending a lot of credibility to the power of this technique, if you pay close attention to what he is saying. i will say it again - it works.
in conclusion, with a little experience, a person can feel when the oil is saturated. with me, it feels like it looses its viscosity. once the oil is full, it is definitely time to spit and rinse!!!