The main ingredient of the pesticide Roundup will be added to a list of chemicals that California believes are linked to cancer, and products that contain the compound will have to carry a warning label by next year.

That designation under the state’s Proposition 65 rules won’t keep the chemical, glyphosate, off fields or garden store shelves. That’s because the proposition does not set rules on how chemicals are used. It just requires a warning that ingredients are “known to the state of California to cause cancer and birth defects and other reproductive harm.”

Federal and state officials who can restrict or ban pesticides so far have said the chemical, one of the most widely used weed killers, has low toxicity and can safely be sprayed on food crops, gardens, parks and golf courses if users follow instructions.

Last year the federal Environmental Protection Agency decided glyphosate was not a carcinogen, setting off howls of protest from advocacy groups, and shifting their long-running battle with Monsanto to California.


The acute animosity toward Monsanto stems from the company’s marketing of seeds that have been genetically modified to withstand its patented Roundup herbicide, uniting the two bete noirs of the environmental and food safety movements — agrochemicals and genetically modified organisms.

Glyphosate is sprayed on more than 200 crops across 4 million acres in California, including 1.5 million acres of almonds, making it the most widely used herbicide, according to the state Department of Pesticide Regulation, a branch of the state EPA.

School districts in Burbank, Irvine and Glendale have banned the chemical from their properties.

The state Environmental Protection Agency began the process of requiring the warning label nearly two years ago, but Monsanto sued.


The company, which is soon to be absorbed into agrochemical giant Bayer, accused the state Office of Environmental Health Hazard Assessment, a branch of the state EPA, of “cherry-picking” the science to justify the warning label. A state Superior Court judge ruled against the company in March, clearing a path for Monday’s decision.

“California’s decision makes it the national leader in protecting people from cancer-causing pesticides,” said Nathan Donley, a senior scientist at the Center for Biological Diversity, one of the groups that has pushed to ban glyphosate. “The U.S. EPA now needs to step up and acknowledge that the world’s most transparent and science-based assessment has linked glyphosate to cancer.”

Donley was referring to the International Agency for Research on Cancer, part of the World Health Organization. Critics say that agency focused on the hazard posed at any dosage, rather than on risks associated with the kind of exposure that would be expected on farms and in gardens.

A Monsanto spokesman said the company “will continue to aggressively challenge” the court decision.


geoffrey.mohan@latimes.com

Follow me: @LATgeoffmohan

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