Having jsut gone through months of voice therapy with a specialist, I did say I sometimes did belting blues. Her answer was yes you can sing it without harming your voice but you must know how to do it properly or you will damage your voice irrevocably. I suggest you contact the Voice Care Network [look on their website] who will put you in touch with a Speech and Language Therapist near you who will be able to help. Don't go on harming your voice learn how to do it properly.