http://neuromuscular.wustl.edu/nothe...yridoxineintox

http://neurotalk.psychcentral.com/thread30724.html

http://en.wikipedia.org/wiki/Vitamin_B6#Toxicity (Take a look specifically at the references here)

The problem with B6 toxicity is that almost all the references are based on anecdotal reports--there really hasn't been a systematic review of those, or controlled experiments. There is some evidence, though, that this happens mostly in those with a genetic malfunction that makes conversion to the active form of pyridoxine difficult, which allows a buildup of precursor B6 in the body. Those who take the already converted/activated p-5-p form seem to avoid this problem.