Eloise case diet pill chemical was used in Great War armour piercing shells

Dr Simon Cotton, a senior lecturer in chemistry at the University of Birmingham, said scientists had been aware of the danger of Dinitrophenol (DNP) for nearly a century.

Miss Parry died on April 12 after taking diet pills that she had bought on the internet that are believed to contain the toxic chemical.

Dr Cotton has said that during the First World War, DNP was sometimes mixed with other chemicals and used in munitions.

He said: "It is a very dangerous chemical and scientists have been aware of this for nearly a century.

"Just like TNT, it was found to be toxic to the munitions workers handling it.

"Many of them lost weight dramatically and some even died simply by absorbing it through their skin.

"The commercial use of DNP is as a pesticide or herbicide and in 2009, 11 workers in a Chinese chemical factory – plus nine of their relatives – contracted DNP poisoning, their skins turned yellow or even black and two died," he said."

Eloise's mother, Fiona Parry, said just two of the pills containing DNP would constitute a lethal dose, but her daughter had taken eight.

The chemical has been linked to a number of deaths. In 2013, 18-year-old rugby player Chris Mapletoft died, as did 28-year old High Wycombe bodybuilder Sean Cleathero in 2012, when his temperature rose to 42C.

That same year 23-year-old Leeds University medical student Sarah Houston died after consuming DNP she bought over the internet.

Dr Cotton warned people not to buy pills over the internet.

Meanwhile, a friend of Eloise has said she needed more help from the health service.

The friend, who did not wish to be named, told a radio interviewer: "I think she needed to be an in-patient. She could no longer keep herself safe.

"I was with her when she told medical staff that she could no longer keep herself safe and that she needed their help."