Richard Knoppow on Pyro toxicity: Source (http://www.viewcamera.com/pyro.html)
“Pyrogallic acid is toxic but one must be careful in interpreting MSDS: mostly they are written for industrial users of substances who use and store them in very large quantity.
In our laboratory at work, we have a large MSDS library which I consult frequently. I agree with Knoppow that one must be careful in interpreting any MSDS. Different MSDS on the same chemical often give contradictory information.
And all too often, the MSDS appears to be selling a corporate position.