Why isn't the threat of legal action a sufficient incentive against this? It might not help to prevent freak accidents but for known health problems like the radium, if the managers are documented to know about it without taking action, then they would spend the rest of their lives at risk of going to prison, or at least the company being fined.
Of all the things I've seen scare people in plants, OSHA wins, hands down. The environmental agencies probably come neatly in second. Fines can be paid, lawsuits settled, but OSHA will come in and lock down your facility and stop production. They're like the nuclear deterrent of plant safety (and while it can be said that stuff still gets by, there is always the omnipresent fear of getting caught, and even that helps raise safety awareness).
They have teeth, such that just baring their teeth can be enough to incite action.
Because them knowing about could also be coupled with them knowing that they can defend against such action. Either advised by their legal team based on existing laws or based on how well "written down" the evidence is.
In this case for example, it was an iconic case. But each of the Radium Girls didn't really get that great of a deal out of it ($10k in 1920's money). And US Radium Corp didn't exactly crumble after the lawsuit. It functioned for many decades after.
It's hard to pin liability on specific individuals without documentary proof, as verbal conversations are ephemeral and criminal liability usually requires a demonstration of intent which is hard to establish in court.
companies can build the cost of fines into the price of their product to some extent, and whenever a company is fined a large amount there's always a contingent of unquestioningly-pro-business people available to denounce it a 'gubmint shakedown,' and make noises about tyranny, liberty, due process and so on - regardless of the degree to which the regulatory action is warranted.
Suing someone is a huge pain in the butt and costs a lot of money. It's also extra difficult when you are trying to sue someone who knows what they are doing is wrong and is actively trying to cover their tracks and obstruct the case. At the same time there is a concerted effort among corporations to limit their liability through legislation, and via PR campaigns against lawyers and lawsuits.
A different, but somewhat similar issue came up with PVC (?); hairspray contained PVC until the health hazards became commonly known while industrial users continued exposing workers to those same hazards. The reasoning, as I understand the story, was that the companies' liability to customers (i.e. hairspray users) was unlimited, while the liability to employees was limited.
