Not so white the dʹalun stone?

Following the scandal surrounding dʹaluminium salts in deodorants, there was much talk of dʹalun stone as the alternative of choice. As time went by, however, certain doubts began to surface: suspected of containing harmful substances, it might not be so white after all. So what should we think? Should we do without it? Should certain precautions be observed, or can we use it with our eyes closed?