If you are interested in this subject, I highly recommend picking up a copy of Deborah Blum’s excellent 2011 book The Poisoner’s Handbook (https://www.amazon.com/Poisoners-Handbook-Murder-Forensic-Me...), which tells the stories of a bunch of different chemical catastrophes from the same period. Radium is covered, as well as such other “what were they thinking?” stories as the introduction of lead into gasoline and the poisoning of industrial alcohol by the government during Prohibition in a misguided effort to keep it from being turned into bootleg liquor. It’s full of fascinating case studies, and Blum has an engaging writing style that makes it a good read.

If you prefer to watch your history, PBS’ American Experience documentary series did an episode based on Blum’s book (see http://www.pbs.org/wgbh/americanexperience/films/poisoners ); it can be streamed via a bunch of different video services.

Midgely absolutely knew of the risks of lead, or at least he should have -- he had to take a leave of absence from his work to recover from a case of lead poisoning, and so many workers in the plant that made tetraethyl lead (TEL) developed inexplicable odd behaviors from their own cases that locals referred to the plant as "the loony gas building."

Worse still, Midgely worked actively to cover the risks of lead up. He even held a press conference in 1924 where, to assure reporters that TEL was safe, he washed his hands in a bowl of the stuff (https://www.bbc.com/news/business-40593353)!

Deborah Blum covered the whole story in her excellent 2011 book, The Poisoner's Handbook (https://www.amazon.com/Poisoners-Handbook-Murder-Forensic-Me...). Blum excerpted the story of TEL for a piece in Wired, which can be read here: https://www.wired.com/2013/01/looney-gas-and-lead-poisoning-...