"Crude oil shipped by railroad from North Dakota is drawing fresh scrutiny from regulators concerned that the cargo is adding environmental and safety hazards, something that analysts say could raise costs."

"The U.S. Federal Railroad Administration is investigating whether chemicals used in hydraulic fracturing are corroding rail tank cars and increasing risks. Separately, three pipeline companies including Enbridge Inc. warned regulators that North Dakota oil with too much hydrogen sulfide, which is toxic and flammable, was reaching terminals and putting workers at risk.

Until last month, safety advocates’ chief worry was spills in derailments. After tanker cars blew up July 6 on a train in Quebec, investigators in Canada are considering whether the composition of the crude, which normally doesn’t explode, may have played a role in the accident that killed 47 people. The oil was from North Dakota’s Bakken shale."

Jim Efstathiou Jr. and Angela Greiling Keane report for Bloomberg News August 13, 2013 [2]