I'm assuming that your white hair is due to age rather than being naturally fair when I say this. White hair is usually a lot more frail, therefore it is more easily removed. Kind of like how when you start to get white hairs on your head they will be broken off and get kinked and stick out (you know, exactly like you don't want them to?) Same deal. They're too frail to hold pigment anymore and are easily damaged, hence the breaking. I'd imagine it wouldn't be too hard for an electrologist to get rid of those since they are hairs that are generally on their way out anyhow.