In a move celebrated by scientists and activists, California on Monday announced it would add glyphosate—the active ingredient in the Monsanto-produced weed killer Roundup—to its list of chemicals known to cause cancer.

"California's decision makes it the national leader in protecting people from cancer-causing pesticides."
—Nathan Donley, Center for Biological Diversity

The decision, made by California's Office of Environmental Health Hazard Assessment (OEHHA), was reportedly precipitated by the World Health Organization's classification of glyphosate as a "probable carcinogen" in May of 2015.

"California is required under the Safe Drinking Water and Toxic Enforcement Act of 1986, better known as Proposition 65, to publish a regularly updated list of chemicals thought to cause cancer or birth defects," Newsweek reported.

Monsanto has been quick to respond to the move; as USA Today's Emily Bohatch noted, Monsanto is appealing a ruling on a case it brought against California last year, when the OEHHA first attempted to add glyphosate to its list of cancer-causing agents. 

In response to the agrochemical giant's legal maneuvering, activists and scientists have insisted that Monsanto's motive is profit alone—not scientific accuracy or the health of the public—and hailed California's decision as a step in the direction of justice.

The Center for Biological Diversity (CBD) noted in a press release on Monday that a recent analysis "found more than half of the glyphosate sprayed in California is applied in the state's eight most-impoverished counties."

"The analysis also found that the populations in these counties are predominantly Hispanic or Latino," CBD continued, "indicating that glyphosate use in California is distributed unequally along both socioeconomic and racial lines."

Nathan Donley, a former cancer researcher and a senior scientist at the CBD, called California's move "remarkable" and congratulated the state for standing up to "special-interest politics [that] hamstring our federal government from taking action to protect people from this dangerous pesticide."

"California's decision makes it the national leader in protecting people from cancer-causing pesticides," Donley concluded. "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."