WASHINGTON — Federal officials are examining potential barriers, such as a fear of retaliation from employers, that may explain why only about one-third of coal miners participate in a program to screen for black lung disease even as the number of workers suffering from the deadly condition is rising.

The lack of participation concerns lawmakers and the federal agency that administers the program, the National Institute for Occupational Safety and Health. The institute, part of the Centers for Disease Control and Prevention, plans to issue a congressionally mandated report on the issue.

The consensus among health advocates is that miners are afraid that participating in the screenings will hurt their careers because employers don’t want to have to deal with a sick employee.

“It’s a known fact that there have been people who were either dismissed or discriminated against because they went for black lung screening or benefits,” said Brenda Marion, project director for the New River Health Black Lung Clinic in Scarbro, W.Va.

She said that the perception among some miners is that if they are screened and a problem is found, the employer might fire them because of a reluctance to pay for their health care, or because the company doesn’t want to move the employee into a job with less exposure to dust.

The Coal Workers’ Health Surveillance Program has offered coal miners free chest X-rays and other screening services since 1970. In addition to helping miners find out if they’re affected, the program also collects data about the disease’s prevalence, and last year found that it had reached its highest level in 25 years. The institute that runs the program called the situation an epidemic.