7. Yenisei River (Russia)
According to studies, the Yenisei River has been contaminated, severely in places, by three decades of discharges of radioactive particles from a factory making bomb-grade plutonium. In downstream villages, experts have found a disturbing statistical pattern of illnesses: an increase in children with leukemia, in breast cancer among women and a higher death rate. All are possible effects from radiation exposure and valid reason to be one of the scariest deadliest rivers in the world.