California declares Roundup ingredient a carcinogen

The weed killer will now have to carry a warning saying it may cause cancer

California today officially listed glyphosate, the key ingredient in Monsanto’s Roundup weedkiller, as a chemical known to cause cancer under the state’s Proposition 65 law. The widely used herbicide must now carry a label warning California consumers that it can cause cancer in people.

It's the first time a governmental authority anywhere in the world has issued a regulation based on Roundup’s potential carcinogenicity. The state had earlier announced its intention to do so but was delayed by a court challenge filed by Monsanto, which manufactures Roundup. The challenge was dismissed last week.

Monsanto issued a statement in response to the court's ruling, calling it "unwarranted on the basis of science and the law."

The California Office of Environmental Health Hazard Assessment (OEHHA) still must set a limit for acceptable daily exposure to the herbicide. Scientists at the agency have proposed a limit of 1.1 milligrams a day – 127 times less than the U.S. Environmental Protection Agency’s legal allowance for the average-sized adult.

Good but not enough?

The Environmental Working Group urged the state to go further and set much lower exposure limits to protect the health of children and fetuses.

“With this action today listing glyphosate as a cancer-causing chemical, California continues to lead the nation in implementing laws to protect human health and the environment,” said EWG President Ken Cook. “This is a significant blow to Monsanto, but a victory on behalf of the public, which could set the stage for similar actions in other states across the nation.”

EWG said the state should set a much lower limit for glyphosate – no more than 0.01 milligrams per day – which would protect all Californians, including children.

“While we applaud today’s action, we do believe the state can take additional steps to further protect its most vulnerable populations from this dangerous chemical,” said Cook.

Targeted by environmentalists

Glyphosate has been a target of environmentalists and some health officials since the World Health Organization (WHO) issued a finding in 2015, saying the substance is “probably carcinogenic.”

Monsanto sued California 18 months ago to block it from adding Roundup to the Proposition 65 list of chemicals known to cause cancer, birth defects, and other reproductive damage. Prop. 65 requires the state to label all substances identified as carcinogenic or dangerous to the reproductive process.

Monsanto filed the suit in Fresno County, Calif., maintaining glyphosate is not harmful. The use of the chemical has increased in recent years, as agricultural operations have used it on a variety of crops. Consumers are likely most familiar with it as the active ingredient in the weedkiller Roundup, used to control unwanted vegetation in suburban lawns and driveways.

The company said California's Office of Environmental Health Hazard Assessment tested glyphosate in 1997 and 2007 and found it did not present a cancer risk to humans.

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