The Law and Ethics of Male Circumcision: Guidance for Doctors
British Medical Association
Journal of Medical Ethics
Vol. 30, No. 3 (Jun., 2004), pg 260
"The medical harms or benefits have not been unequivocally proved except to the extent that there are clear risks of harm if the procedure is done inexpertly.
Indeed, it would be difficult to formulate a policy in the absence of unambiguously clear and consistent medical data on the implications of the intervention."
So in other words, there is no clear scientific evidence for or against circumcision.