If it's harmless to humans it's because it's been designed to be...
So they say, and it might well be. But over the years I've seen plenty such claims that turned out to be untrue. It could be legit, but I've yet to find any spray for self defence from either human or animal attack towpaths bore scrutiny in a court.
I've also seen claims on everything from such sprays through to horse riders hi vis tabard with claims like "approved by such and such police force" etc and not one or those is true either.
What about all the everyday aerosols in the shops?
what about them?
Even, any, hairspray becomes an offensive weapon if you carry it with intent to to use it as a weapon. Of course proving that is a separate matter altogether, but that is nevertheless how the law goes on that one. Google
mens rea and then be confused and astonished that anyone anywhere ever gets arrested for anything.
As for legitimate aerosols that might be noxious - you wouldn't want to be sprayed with fly killer, after all - you need to bear in mind that I didn't write the law, that the law often contradicts itself, and is so full of holes you could drive a bus through it. That's where
case law comes in, but that is a can of worms for you to gen up on yourself.
Put it this way - you be my guest by all means, but I wouldn't carry
any aerosol with any intent to defend myself from any type of attack, not even deodourant. If it goes wrong it isn't you, me or an advert that decides what is legal - its the the Court, and from what I've seen over the years the chances of success are essentially zero. And lack of success in defending on a firearms charge is very bad ju ju.
To summarise - it might be legit, they may even think its legit, but the consequences if a court decides otherwise are so severe I wouldn't chance it. If you think otherwise then all power to you.