  Ultra high energy cosmic rays (UHECRs) probably originate in extreme
conditions in which extra dimension effects might be important. In this paper
we calculate the correction in black hole accretion mechanisms due to extra
dimension effects in the static and rotating cases. A parametrization of the
external Kerr horizons in both cases is presented and analysed. We use previous
calculations of upper limits on the UHECR flux to set limits on the UHECR
production efficiency of nine sources. The upper limit on the UHECR luminosity
calculation is based on GeV-TeV gamma-ray measurements. The total luminosity
due to the accretion mechanism is compared to the upper limit on UHECRs. The
dependence of the UHECR production efficiency upper limit on black hole mass is
also presented and discussed
