Federal District Judge William Shubb said the warnings would be misleading because glyphosate is not known to cause cancer, according to court documents filed on February 26 in California.
The state’s Office of Environmental Health Hazard Assessment (OEHHA), which planned to require the warnings, could not immediately be reached for comment. The office previously stood by its decision to include glyphosate on the state’s list of products known to cause cancer.
“Given the heavy weight of evidence in the record that glyphosate is not in fact known to cause cancer, the required warning is factually inaccurate and controversial,” Shubb wrote.
The judge’s decision is important for Monsanto because glyphosate is widely used by farmers, who apply it to genetically engineered crops, and consumers, who spray it on their lawns. The company’s agricultural productivity segment, which includes glyphosate, had net sales of $3.7 billion in fiscal year 2017.
Monsanto, which is being acquired by Bayer AG, along with U.S. farm groups sued California in November to stop the warnings.
California added glyphosate, the main ingredient in Monsanto’s herbicide Roundup, to its list of cancer-causing chemicals in July 2017 and had planned to require that products containing the chemical carry warnings by July 2018.
The government of the most populous U.S. state acted after the World Health Organization’s International Agency for Research on Cancer (IARC) concluded in 2015 that glyphosate was “probably carcinogenic.”
Other studies have found the opposite, including one released by the U.S. EPA in December.
A large, long-term study on glyphosate use by U.S. agricultural workers, published in November as part of a project known as the Agricultural Health Study, or AHS, also found no firm link between exposure to glyphosate and cancer.
Reuters reported in June that an influential scientist was aware of new AHS research data while he was chairing a panel of experts reviewing evidence on glyphosate for IARC in 2015. He did not tell the panel about it.
“Glyphosate is a vital tool that growers have trusted to provide safe, affordable food,” said Chandler Goule, chief executive officer for the National Association of Wheat Growers.
The case is National Association of Wheat Growers et al v. Lauren Zeise, director of OEHHA, et al, U.S. District Court, Eastern District of California, No. 17-cv-02401.