But the jobs are also hazardous, with fatality rates that are seven times the national average across all industries. Nearly a third of the 648 deaths of oil field workers from 2003 through 2008 were in highway crashes, according to the most recent data analyzed by the federal Centers for Disease Control and Prevention. By contrast, highway crashes caused roughly a fifth of workplace fatalities across all industries in 2010.

“The growth of this industry is a big concern because it’s adding so many more trucks on the roads and its drivers don’t have to follow the same rules as others,” said Henry Jasny, a lawyer for Advocates for Highway and Auto Safety

Bending the Rules

In 2005, as the drilling boom accelerated, federal labor officials noticed a worrisome trend: fatalities among oil and gas workers rose 15 percent from 2003 to 2004. After investigating, the C.D.C. found that with the growth of the industry, not only were more workers dying but, more surprising, the fatality rate was increasing, meaning the relative risk was rising. Shifts grew longer, more inexperienced workers were hired and older rigs were being pressed into service, the agency concluded.

“Unless changes are made to increase worker safety, the high fatality rates described in this report are likely to continue,” the agency warned, citing the growth of the industry and its trucking exemptions.

Some worker safety experts point to other factors contributing to the industry’s fatality rate. Drug use is common among workers at some sites. Few workers are unionized, meaning they are less able to complain about safety problems without fear of being fired.

Some experts have called for increased oversight. An analysis by The New York Times of more than 50,000 inspection reports indicates that as the number of drilling rigs rose by more than 22 percent in 2011 from the prior year, the number of inspections at such work sites fell by 12 percent.

David Michaels, an assistant secretary of labor with the Occupational Safety and Health Administration, said that his staff was aggressive about enforcement but that companies were not required to alert his agency when their truckers crashed on public roads. Nor do they have to inform his agency when drilling starts, making timely inspections difficult, he added.