Having also the normal safety precaution, what are the less toxic or dangerous ones?
Staining developers contain either pyrogallol or catechol, both are more toxic than metol or hydroquinone. Use of rubber gloves is recommended. Skin absorption of catechol has been linked to chronic kidney disease.
A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.