Canadian pipeline company TransCanada aims to build the Keystone XL oil pipeline to carry so-called tar sands oil from Alberta province to refineries along the southern U.S. coast.
The pipeline has become politicized, with Republican backers touting its employment and energy security benefits.
The White House denied a permit for TransCanada after lawmakers in Nebraska objected to the initial route planned through the Ogallala Aquifer.
A 24-page report from Cornell University, "The Impact of Tar Sands Pipeline Spills on Employment and the Economy", concludes many claims about the project are inflated. The study states that a total of 20 permanent pipeline operation jobs are expected in the six states along the pipeline route.
"Meanwhile, the agricultural and tourism sectors are already a major employer in these states," the report read. "Potential job losses to these sectors resulting from one or more spills from Keystone XL could be considerable."
The report adds there is "strong evidence" that pipelines like Keystone XL will leak because of the corrosive nature of tar sands oil.
The largest and most expensive spill of tar sands oil occurred in southern Michigan in 2010. The Cornell University report estimated that spill cost around $725 million.
The report was published by Cornell's Global Labor Institute, which says it works with trade unions to develop solutions to major social, economic and environmental challenges.