We've been using white noice to help with sleep since our baby was born and after 15 months I'm concerned that it could cause hearing damage or something else.
Low volume white noise will not cause hearing loss. As we age the white noise, soft music, fans, and the like become normalized and in some cases create a dependency where it is needed to be able to stay asleep. Sleepless nights during a power outage can be one way to tell if you have been normalized on white noise.
There is one study in particular, which I can't for the life of me find the source right now but if I do I will link it, that suggest that low frequency / background noise in some people can disrupt normal concentration and cause a stress response. Since stress has already been linked to certain health concerns, it is not unreasonable to link white noise to health issues - again, only in certain people. I am one of those people. Certain types of music and white noise trigger that stress response in me for an unknown reason.
As for your baby? She's likely fine. Babies often wake up during the lighter phases of their sleep cycle (this is normal, some wake more often than others), but most will outgrow that with age. If the white noise helps drown out the other noises in the house so she doesn't wake up and you want to wean her off it, between 2 and 3 is probably the easiest ages to do that. If you wait too long, they will become normalized to the white noise and have trouble sleeping without it.
My only concern with white noise would be volume and proximity, which is the same concern I would have with a child listening to music through headphones at a loud volume.