Kazakhstan’s nuclear test zone, deserted and largely forgotten, will continue to be a health risk until the huge site is thoroughly cleaned up, say experts.

Despite being closed down 17 years ago, academic researchers and pressure groups say the incidences of cancer, congenital defects, retarded development and psychiatric disorders around the abandoned site at Semipalatinsk, in the country’s northeast, are much higher than elsewhere in Kazakhstan. Some 1.7 million people are believed to have health problems caused by exposure to radiation, even though above-ground blasts were halted in 1962 and underground testing in 1989.