Was it really accidental though? The dangers of lead exposure were known at that time. Midgely himself got lead poisoning in 1923 as a result of his tetraethyll

Was it really accidental though? The dangers of lead exposure were known at that time. Midgely himself got lead poisoning in 1923 as a result of his tetraethyllead experiments so there's no way they couldn't have known it was harmful even in the very early days of leaded gasoline.