Nopes it has been proven the presence of radioactivity but still they are searching for the reasons.....
A heavy layer of radioactive ash in Rajasthan, India, covers a three-square mile area, ten miles west of Jodhpur. Scientists are investigating the site, where a housing development was being built.
For some time it has been established that there is a very high rate of birth defects and cancer in the area under construction. The levels of radiation there have registered so high on investigators' gauges that the Indian government has now cordoned off the region. Scientists have unearthed an ancient city where evidence shows an atomic blast dating back thousands of years, from 8,000 to 12,000 years, destroyed most of the buildings and probably a half-million people. One researcher estimates that the nuclear bomb used was about the size of the ones dropped on Japan in 1945.
The Mahabharata clearly describes a catastrophic blast that rocked the continent. "A single projectile charged with all the power in the Universe...An incandescent column of smoke and flame as bright as 10,000 suns, rose in all its splendor...it was an unknown weapon, an iron thunderbolt, a gigantic messenger of death which reduced to ashes an entire race.
"The corpses were so burned as to be unrecognizable. Their hair and nails fell out, pottery broke without any apparent cause, and the birds turned white.
"After a few hours, all foodstuffs were infected. To escape from this fire, the soldiers threw themselves into the river."