Crude oil from North Dakota’s Bakken field may be more flammable and explosive than previously thought, officials now say after a series of fiery railroad accidents. The crude may contain more flammable gasses, be highly corrosive, or more sulfurous than crude from other oil fields, according to the Pipeline and Hazardous Materials Safety Administration (PHMSA). The agency is warning Bakken oil producers to “sufficiently degasify” the crude oil before loading it into rail cars. On Monday, several tank cars carrying Bakken crude exploded after a collision on a remote stretch of track in North Dakota, and last July a runaway train carrying the crude derailed and exploded in Lac-MÃ©gantic, Quebec, killing 47 people. U.S. railroads have asked manufacturers for safety upgrades to tank cars that carry Bakken crude, which could cost the industry roughly $3 billion, Reuters estimates. Trains carried nearly 700,000 barrels of Bakken crude each day in October, a 67 percent increase over the previous year.