I actually looked this up for you and no, masturbation does not lead to cancer or have any other heinous side effects. You would have to do it all day long for like 30 years for it to have any bad effect. There are a lot of things to stress over in this world but this is not one of them. Avoid anything with Talc as that can cause ovarian cancer, but it doesn't sound like you would be using that anyway.
Probabaly not. It doesn't make you go blind either.