Chemical castration is humane? Fuck off.
Again, I point you to Alan Turing.
It is humane because it does not cause any harm.
DA FUQ?One, you're taking away their sex drive, a natural, healthy element in almost all humans. There is little difference, really, between that and chopping off someone's hand.
Two, yes it does cause harm, psychological harm, leading potentially to suicide. (Hey, doesn't your sky-daddy* think that's wrong too?)
The person probably individually most responsible a) for keeping Nazi Germany from successfully invading Great Britain and b) for shaping the modern world was chemically castrated and committed suicide because of it.
*Though actually that's you, brain studies have looked into this and found that when you're asked your opinion on a matter, one part of your brain lights up, and when you're asked what you think someone else's opinion on a matter is, another part lights up... guess which part lights up when you're asked God's opinion on an issue.