Doctors in Russia are treating at least 25 servicemen who have been poisoned with the highly toxic metal thallium.
They found the powdery substance in a can at a dump near their base in Khabarovsk in the Russian Far East.
Unaware of the danger, the conscripts added it to the tobacco they smoked, and used it as talcum powder on their feet, military officials said.
Several of the soldiers are said to be in a very serious condition, with their hair falling out.
They were flown to St Petersburg Academy of Military Medicine on Friday.
An army source told Interfax news agency the soldiers had used the thallium powder "for dusting their foot
wraps in order to sweat less".
"They also sniffed the chemical and added it to their tobacco," he added.
Thallium - a toxic substance that is banned in some countries such as the US - is sometimes used in rat poison.
Extensive exposure can cause damage to the liver, kidneys, and other organs, as well as hair loss.
The Russian authorities have launched a criminal
investigation for breach of public health regulations.