Risk compensation is a theory that developed from observing that human beings changed their behaviour according to their assessment of risk level. It basically states that human beings will do more of something if they feel they have a low risk of harm, or do less of something if there is a high risk of harm. When applied to circumcision it suggests that if circumcised men feel they are at less of a risk of acquiring an STI/HIV infection, then they are less likely to practice safe sex and more likely to practice risky sexual behaviour, leading to the unwanted outcome of placing circumcised men and their partners at greater risk of infection. We are already now seeing HIV infections rising in Africa following circumcision campaigns = http://mondofown.blogspot.com.au/2014/05/media-reports-showing-rise-in-hiv.html
When you look at epidemiological health outcome data, you find that the USA with the highest adult circumcision rate in the western world also has the highest rates of HIV & STI infections in the western world. In Africa 10 of 18 nations, the circumcised populations have higher HIV. In one longitudinal study in NZ which followed males from birth they found no statistical difference in STI infections and circumcision status. In a recent study from Puero Rico they found circumcised men had higher STI infections: https://www.ncbi.nih.gov/m/pubmed/22897699/ What all this data suggests is one of 2 things, firstly that circumcision status does not prevent HIV/STI infections, or secondly that if circumcision does provide some protection against HIV STI infections, then high risk behaviour or risk compensation behaviour cancels it out.
The latest research shows risk compensation taking hold in South Africa
In realty, Circumcision is not a medical solution to HIV/STI prevention, circumcision is just a deeply embedded cultural practice which forever seeks to justify itself because its victims need for validation. In this current age, circumcision cultures try to defend the practice by pointing to medical benefits, which epidemiological outcome studies have repeatedly shown dont exist at population levels. Europe & Japan with the lowest circumcision rates have the lowest HIV/STI's rates in the world, and its people live the longest with lowest levels of disease. Proof circumcision not required for good health.
If one is truly interested in reducing the risk of HIV/STI infections then Education, Behaviour Change, Condoms, HPV Vaccination & Retro-Viral medication are much more effective without all of the problems associated with circumcision.
The human tendency to risk compensate means circumcision is at the very least useless or at its worst, a risk to public health by endangering both men and women to infections, disease and ultimately death in some situations. (Death has been documented from circumcision itself, and many circumcised men have died from HIV/AIDS around the world, just look at America)