Half life on soil is almost 13 hours and slightly less in water. That's a little more than a few hours. It's the exposure during application and shortly thereafter.
So what that means is that after 24 hours there is very little left. And if u spray a few days from harvest it's gone.
Even if u spray the day of harvest then by the time the buds are cured its gone.
So yeah, it's fine to use.
And stuff worse than that is on pretty much every vegetable and fruit that you eat.
People get this thing in their head that cannabis is supposed to be totally free of everything. It's an agricultural product so often times that isn't possible. Shit happens. Bugs find their way in through your clothes hair, cracks in the wall, whatever. You can either apply a safe pesticide or trash an entire crop. I choose the former.
I wouldn't spray something like avid on them, but pyrethrin is fine