OSHA was created in 1971. It has been greatly hindered by being understaffed and underfunded since its inception.
Also from Wikipedia "The following are exempted from OSHA regulations:
Mine and quarry workers (regulated by the Mine Safety and Health Administration)
Independent contractors and other self-employed individuals[8]
Public sector employees (covered only in jurisdictions with state plans; the United States Postal Service is covered under the Postal Employees Safety Enhancement Act)[9]
Domestic workers (workers whose workplace is a household)[10]
Flight crews (covered by the Federal Aviation Administration)[11]
Farms employing only family members and farms employing fewer than 10 employees with no migrant labor housing[12]
Additionally, workplaces participating in OSHA's Voluntary Protection Programs are exempted from programmatic inspections, though they can still be subject to accident-, complaint-, or referral-initiated inspections.[13]"
OSHA is another one of those agencies that gets screamed about by the right wing, but really leaves an awful lot of people unprotected. With the political failure of politicians to actually care about worker safety, we end up with the situation we are in today. According to the AFL-CIO "In 2012, 4,628 workers were killed on the job in the United States, and an estimated 50,000 died from occupational diseases, resulting in a loss of 150 workers each day from hazardous working conditions. Over the past four years, the job fatality rate has largely been unchanged with a rate of 3.4 deaths per 100,000 workers in 2012."
While there had been attempts to regulate mine safety going back to the 1890's, MSHA was created by the Federal Mine Safety and Health Act of 1977 (Mine Act) and given some real enforcement authority. But the mine owners have prevented or illegally ignored mine health and safety regulations. We can only hope that Don Blankenship ends up with prison time. Speaking as a former regulator, nothing gets the attention of these business owners, like sending one of them to jail for something everyone knows they all do. It straightens them all up in big hurry. If the Obama administration can send that guy to prison, which he rightly deserves, we will see mine safety improve really fast and miners can stop dying untimely deaths and dealing with crippling diseases like black lung.