Monsanto has stepped up its defense of glyphosate by filing a lawsuit in California seeking to prevent the state from adding the herbicide to its list of known carcinogens.
The company filed the suit against the state’s Office of Environmental Health Hazard Assessment and the agency’s acting director, Lauren Zeise.
California law requires the state to keep a list of cancer-causing chemicals to inform residents of their risks.
The state environmental agency said in September that it planned to add glyphosate to the list after the World Health Organization’s International Agency for Research on Cancer classified it as a probable human carcinogen in March.
Monsanto has disputed the assessment, citing decades of studies deeming glyphosate safe, including a 2007 study by OEHHA that concluded the chemical was unlikely to cause cancer.
Glyphosate is the main ingredient in Monsanto’s Roundup herbicide.
“The IARC classification of glyphosate is inconsistent with the findings of regulatory bodies in the United States and around the world, and it is not a sound basis for any regulatory action,” said Phil Miller, Monsanto’s vice-president of regulatory affairs.
Monsanto’s lawsuit argues that listing glyphosate under Proposition 65, as the state’s law is known, based on IARC’s classification cedes regulatory authority to an “unelected, undemocratic, unaccountable and foreign body” that is not subject to oversight by any state or federal entity.
Monsanto argues that the lack of oversight violates the company’s right to procedural due process under California and U.S. law.
A listing would also require Monsanto and others offering products containing glyphosate to provide a “clear and reasonable warning” to consumers that the chemical is known to cause cancer, damaging Monsanto’s reputation and violating its First Amendment rights, the company said.
Roundup is used by farmers around the world, generating Monsanto $4.8 billion in fiscal 2015 revenue. Genetically modified seeds designed to tolerate glyphosate are immensely popular among corn and soybean growers.
However, questions from environmentalists and other critics about the safety of the herbicide have dogged the company for years.
Since IARC’s classification last year, Monsanto has been named in numerous lawsuits accusing the company of knowing of the dangers of glyphosate for decades.