Try the wheel cleaning acid from eBay. I picked up the wrong bottle from the garage the other day and the weeds were brown and floppy within a couple of hours. Not sure what the dog would make of it, though our cat survived too tell the tale.
Hydrogen peroxide wtf! You're worried about environmental / health implications of a heavily regulated and type approved product for your application which works on the biology of the target weeds but are happy to consider completely unregulated chemicals which might work on the basis of them being very nasty chemicals.
The risk of cancer with this is so small I believe it's less than alcohol and we are talking about putting it on the patio not drinking it! If anyone's worried about the cancer risk with glyphosate they really need to make sure they are eating only organic food.
H2O2 is a short lived aggressive oxidiser (dependent upon concentration) that degrades to benign components and is unpredictable when handled due to it catalysing readily.
You're exchanging environmental concerns for H&S concerns really.
It's only a weed killer in the same way that napalm is really!
There's no evidence that organic food reduces cancer rates.
Any nettles?
