The Techa was the most radioactive river in the world yet thousands used it daily Alexey Zhenin

The village of Satlykovo, just east of the Ural mountains in Russia, is no more. The main street is knee-high in nettles, its houses bulldozed. All around, the land is blooming. Nearby forests harbour elk and wild boar. The lake is home to radioactive carp.

One morning 59 years ago, soldiers came and ordered the villagers to leave. “Their cattle were destroyed and buried, and they could not even take with them the clothes they stood up in,” says Islam Bagautdinov, who has driven me here through military checkpoints.

There were no explanations. The troops didn’t say that there had been an explosion at a factory a few kilometres away; or that the blast had propelled radioactive dust into the air, forming a deadly plume that rained out across Satlykovo and the surrounding countryside. The very existence of the Mayak complex, where weapons-grade plutonium was made, was a military secret.

Over the next 600 days, thousands of bemused people from Satlykovo and 22 nearby villages were evacuated, 20,000 hectares of farmland was put out of use and a permanent exclusion zone was created. Barring a few in the CIA, nobody in the outside world would know of it for two decades.

Satlykovo village is now grassland Alexey Zhenin

Through this long period of secrecy, Soviet researchers surreptitiously collected data on the villagers and their children. Now under analysis by Western and Russian researchers, this data is offering new insights into the ways chronic exposure to radiation affects health.

“Waste was just …