A U.S. federal appeals court in Friday ordered the U.S. Environmental Protection Agency to reassess whether glyphosate, the controversial ingredient in Bayer AG's Roundup weed killer, poses unreasonable risks to humans and the environment.

In a 3-0 decision, the 9th U.S. Circuit Court of Appeals agreed with several environmental, farmworker and food-safety advocacy groups that the EPA did not adequately consider whether glyphosate causes cancer and threatens endangered species, Reuters reports.

Groups including the Natural Resources Defense Council, the Center for Food Safety and the Rural Coalition, which represents farmworkers, faulted the agency for rubber-stamping glyphosate despite its alleged harms to agriculture, farmers exposed during spraying, and wildlife such as the Monarch butterfly.

Circuit Judge Michelle Friedland wrote for the Pasadena, California-based appeals court that the EPA did not properly justify its findings that glyphosate did not threaten human health and was unlikely to be carcinogenic to humans. She also faulted aspects of the agency's approval process.

Bayer's Monsanto unit, which makes Roundup, opposed groups challenging the EPA reauthorization. Friday's decision does not prevent people from using Roundup or similar products.

U.S. jury sides with Bayer

Separately, on Saturday a U.S. jury found Bayer's Roundup weedkiller did not cause an Oregon man's cancer, the German agriculture and pharmaceuticals company said on Saturday, handing the firm its fourth consecutive trial victory over such claims.

The verdict, reached on Friday by the Circuit Court of Jackson County, Oregon, is "consistent with the assessments of expert regulators worldwide as well as the overwhelming evidence from four decades of scientific studies concluding that Roundup can be used safely and is not carcinogenic", Bayer said.