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Leaded petrol was safe. Its inventor was sure of it.

Facing sceptical reporters at a press conference in October 1924, Thomas Midgley dramatically produced a container of tetraethyl lead - the additive in question - and washed his hands in it.

"I'm not taking any chance whatever," Midgley declared. "Nor would I... doing that every day."

Midgley was - perhaps - being a little disingenuous. He had recently spent several months in Florida, recuperating from lead poisoning.

Some of those who'd made Midgley's invention hadn't been so lucky, which is why reporters were interested.

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On the Thursday of the week before Midgley's press conference, at a Standard Oil plant in New Jersey, a worker named Ernest Oelgert started hallucinating. By Friday, he was running around the laboratory, screaming in terror.

On Saturday, with Oelgert dangerously unhinged, his sister called the police. He was taken to hospital and forcibly restrained. By Sunday, he was dead. Within the week, so were four of his colleagues - and 35 more were in hospital.

Only 49 people worked there.

'The loony gas building'

None of this surprised workers elsewhere in Standard Oil's facility. They knew there was a problem with tetraethyl lead.

As Gerald Markowitz and David Rosner note in their book Deceit and Denial: The Deadly Politics of Industrial Pollution, the lab where it was developed was known as "the loony gas building".

Nor should it have shocked Standard Oil, General Motors or the DuPont Corporation, the three companies involved with adding tetraethyl lead to gasoline.