How much 3% H2O2 solution is dangerous?

What are some different quantities and their related effects on humans?

Not sure if this is what you’re after, but here’s the material saftey data sheet for 3% hydrogen peroxide.

Basically, the only health hazards are from long-term skin contact and digestion.

Just found another source, here. The lethal dose for 50% of the population (LD50, for those playing at home) as tested on rats is between 370-1500mg per kg of bodymass, while it’s 3-4g/kg on skin.

An extremely rough estimate (the LD50 trial for lab rats don’t scale well, so don’t expect these figures to be accurate) for a 75kg human would be ~28-113grams orally and 225-300 grams via skin contact.

in practice 3% is quite mild and pretty safe. It will bleach your outer skin layer white if left too long and I wouldn’t recommend drinking it, but I had a friend who used to gargle with it (bad breathe). Probably quite irritating to the eyes.