North Dakota issued new rules Tuesday that require energy companies to treat crude-oil pumped from the Bakken Shale to make it less volatile and safer to transport by railroads. In an unprecedented step that comes amid growing concern about the hazards of oil trains moving across the U.S. and Canada, the North Dakota Industrial Commission said it will mandate that well operators strip explosive gases from crude-oil that shows a high vapor-pressure reading. The state regulation will go into effect on April 1, 2015. It requires that companies operating in North Dakota process their crude-oil through equipment at or near well sites that heats up the liquid to burn off volatile gases.