Per Rudeofus - Ciba bleach was con sulfuric. The amateur powder kits were sulfamic. That stuff would ruin your lungs fast, and it is almost
unimaginable that some people used it in opens trays. It will corrode metal drainpipe like crazy. I know a fellow who had to have a lung removed due to Ciba bleach fume scarring. A single serious incident can ruin your lungs for life. Ordinary hardware store muriatic acid is less concentrated hydrochloric, and people add it to swimming pools, yet it has ruined a lot of lungs of the naive, not to mention skin burns. Failing to read the hazard notice, or failing to dilute it way way down has taken people from perfectly healthy to downright lifetime invalid. I worked
with Ciba for years - in a drum processor outdoors! The bleach was easy to neutralize in small drum batches. I also process even RA4 outdoors in analogous fashion, but that's because I'm allergic to it. Even with thing of lower level toxicity, long-term sensitization can be a
distinct threat. Better safe than sorry. Even routine black and white silver printing warrants gloves and decent ventilation.