North Dakota, the epicenter of the oil boom of recent years, saw the highest worker death rate in 2012, labor union federation AFL-CIO said.
The 2012 rate of 17.7 fatalities per 100,000 employees was a large increase from the 7 deaths per 100,000 in 2007, before the energy boom started, The Associated Press reported, citing data AFL-CIO plans to release next week.
Other states with high rates of energy production also saw high work death rates, such as Wyoming, Alaska, West Virginia and South Dakota, the AP reported.
Eric Brooks, director of the Occupational Safety and Health Administration's Bismarck, N.D., office, told AP that about half of the workplace deaths his office investigates are in the oil industry. But the industry is moving toward safer work practices, Brooks said.