Using hairspray can cause hair breakage.
This one’s absolutely an old wives' tale. It takes a lot of force to break hair. (Weight for weight, hair is stronger than steel!). The polymers in hairspray formulas create bonds that hold the hair, but the force to break those bonds is far too weak to cause hair follicles to snap off. That said, overdoing it with hairspray – or any stylers – can cause product buildup, which can lead to dryness, dullness, and split ends. So regularly massage a gentle, clarifying/detoxifying shampoo onto your scalp to remove buildup.