Yes you would need science or medicine to prove that anything done to another human is harmful unless it's something so blatantly obvious as ramming a railroad spike through their head. otherwise it is entirely your opinion that harm has occured. However, circumcision is not a cosmetic surgery. It is a hygenic surgery and as such is coverred by health insurance. I've little doubt that you have an opinion about the hygenic benifits of circumcision but a lot of doctors disagree with you. Don't want to shock you but I'm going to discount their opinions based on yours.
And again I do say opinions because the debate of hygene and circumcision is not decided by any stretch of the imagination, for every study that shows a risk of infection injury without circumcision there is a study that refutes it. Regardless of which side is correct the instance of a foreskin causing a medical issue is miniscule, but not so low as other potential risks that we proactively medicate.
The labia is a sensate organ that faciltates arousal in women as well as keeping sand out of our coochies. The clitoral hood is analogous to the forskin in circumcision but unlike male circumcision female circumcision causes pain during arousal. That being said. If it were the tradition of my people to sheer the clitoral hood or cut the labia and vaginas bearing these surgeries were the dominant perception of female anatomy I wouldn't allow my daughter to be raised with genetalia that differred from the norm. I would either consign her to genital modificaiton or I would move to a country that didn't endorse them.