no but splashed on them it will burn them.

Yes It is, with small plants it is as potent as a weedkiller. Also splashed on mature root vegetables it will taint and spoil the taste.

thanks, what do you suggest to deter cats from using an area i want to plant in as a toilet?

cats love bare ground... cover it with something for now be it mesh or small branches anything that means they have not got easy access to...

I agree with Moon Grower, Jacquelinee.
I've also staked an area like that with canes (whichever ones i could find behind the shed!!!) and that helped the most.
I found shortish ones (all about 2' tall) and stuck them upright in the border, at distances a cat couldn't get through and created a 'boundary' ..... it worked perfectly :-)))))
The plants grew up undisturbed :-)))

Well Jac. I had a problem with something eating my broad beans so I soaked garden string in Amatillox (Jeyes) will do. Then I stretched it between canes at each end of the bed so the each row had smelly string either side. It worked.

I agree cover the ground as cats like freshly dug and clear ground.

Skins of citrus fruit can sometimes work too.....as a double whammy they will attract slugs too!