here, found this:
"Self Defense Sprays - One 4 ounce (118ml) container of mace or pepper spray is permitted in checked baggage provided it is equipped with a safety mechanism to prevent accidental discharge. Self Defense Sprays containing more than 2% by mass of Tear Gas (CS or CN) are prohibited in Checked Baggage."
I guess they're saying they don't care how strong your OC is? Good to know.