Of that age I’d be almost certain they won’t contain asbestos. But outdoors, brake cleaner and a mask won’t do any harm.
As an apprentice in a Truck factory (1990) I remember some of the military stuff still had asbestos warning stickers (not sure if it was clutch or brakes) but all the regular vehicles were asbestos free. So a much newer car is very unlikely to contain anything nasty.
My dad remembers some of the older plants where there was always a fog of dust from grinding asbestos brake shoes (eek).
Rear shoes do tend to last quite a while – they could even still be OE if not owned by a leadfoot! (our last vehicle did 133,000 and was still plenty left on original rear shoes and drums).