Here we go:
Titanium is definitely not toxic at all! Overheat? How should anyone do that? It's melting point is 1668° Celsius ==> 3034,4° Fahrenheit!
The "white coating" is titanium dioxide...which isn't toxic also! It is even a permitted food additive (E 171); You can find it in chewing gum, toothpaste, cough drops...and in many other products!
Here are the characteristics of titanium:
Titanium - Wikipedia
I'm now kind of baffled because you are telling me this and yet going back last year when i was using it i was informed that things were quite the opposite.