CHICAGO, Ill. (Reuters) — U.S. health regulators are facing a lawsuit from environmental organizations seeking to overturn the government’s landmark approval of a genetically modified salmon.

The lawsuit alleges that the Food and Drug Administration failed to consider all of the environmental risks of the fish when it approved it in November.

The groups also said that the FDA cleared the fish, which was made by AquaBounty Technologies, without having the proper authority to regulate GM animals produced for food.

The FDA’s approval of the AquaBounty salmon followed a 20-year review and was the first such approval for an animal whose DNA has been scientifically modified.

AquaBounty is confident the FDA’s approval will stand, said chief executive officer Ron Stotish.

He said the FDA was “extraordinarily thorough and transparent in the review and approval of our application,” he said.

The company has said its salmon can grow to market size in half the time of conventional salmon, which saves time and resources.

However, the lawsuit claimed that the FDA approval process included “an extremely limited environmental assessment” that did not fully evaluate the potential for AquaBounty salmon to escape from the facilities where they are grown.