PORT BYRON, New York — Six weeks before Chris Johnson was born in 1974, the U.S. government issued a warning about a substance that would nearly kill him 30 years later.

The substance was silica, a component of rock and sand that is the scourge of miners, sandblasters and other workers who breathe it in. When pulverized into dust, it can cause silicosis — a scarring of the lungs that leads to slow suffocation — as well as lung cancer.

This was no newly discovered hazard. The ancient Greeks and Romans were mindful of it. Labor Secretary Frances Perkins launched a national campaign against it in the 1930s after the knifelike particles dispatched hundreds of tunnel workers in West Virginia.

The 1974 warning by the National Institute for Occupational Safety and Health said the workplace exposure limit for silica put people in danger. NIOSH urged the U.S. Department of Labor’s Occupational Safety and Health Administration to cut the limit in half.

OSHA finally did so in 1989, only to see its work undone by a court decision. It didn’t try again until 2011. In the interim, Johnson became a bricklayer and developed acute silicosis after a five-month job that enshrouded him in dust. He’s 40 and, on paper, can expect to survive less than five years.

As Johnson’s experience shows, inaction has consequences. Silica — which OSHA says threatens 2.2 million workers, mostly in construction — is a striking example of the government’s failure to properly regulate toxic substances in American workplaces. The silica rule still isn’t finished. If it is enacted despite industry protests, it will be only the 37th health standard issued by the agency in its 44-year history.

It’s an ignominious record given the human and economic costs of work-related disease in the United States. According to a widely cited University of California, Davis, study, an estimated 53,000 people died in 2007 from on-the-job exposures — outnumbering those killed in suicides, motor vehicle accidents, falls or homicides. More than 400,000 others got sick. The price tag: an estimated $58 billion. OSHA puts the annual toll at more than 50,000 deaths and 190,000 illnesses.