Court Knocks Down Monsanto Challenge to California Cancer Chemicals List

Roundup Ruling Reinforces Voters' Choice to Rely on Expert Scientific Bodies

SAN FRANCISCO - Health and environmental groups defeated an effort to exclude the use of expert scientific findings to add the controversial chemical glyphosate to California's list of carcinogens today. Monsanto had been seeking to force California to remove the herbicide from the state’s cancer list, under California's Proposition 65, the 1986 voter initiative that requires California’s Governor to maintain a public list of chemicals known to the state to cause cancer. 

“This is a win for science and democracy. Monsanto doesn't get to tell California how to protect its people from dangerous chemicals or how to run the Prop 65 list," said Rebecca Riley, senior attorney with the Natural Resources Defense Council (NRDC). "The ruling clearly backs the voters' choice to rely on expert scientific bodies to add dangerous chemicals to its list." 

Monsanto challenged the California Office of Environmental Health Hazard Assessment’s proposal to add glyphosate to the Proposition 65 list, following a 2015 finding by the World Health Organization’s International Agency for Research on Cancer (IARC) that glyphosate is a probable human carcinogen. Monsanto attacked California voters’ choice to make IARC findings an independent ground for adding carcinogens to the Proposition 65 list and argued it was unconstitutional. The trial court rejected Monsanto’s arguments and dismissed the case last year. The appellate court affirmed that judgment today. 

"California will continue to use the best science available to make sure people in the state understand the dangers of the chemicals they use, whether the chemical companies like it or not," said Kathryn Phillips, Director of Sierra Club California. 

NRDC, Sierra Club, the United Steel, Paper and Forestry, Rubber, Manufacturing, Energy, Allied Industrial and Service Workers International Union, AFL-CIO, CLC, and the Environmental Law Foundation intervened in Monsanto’s lawsuit, alongside California, and filed a successful companion motion to dismiss. 


The Natural Resources Defense Council (NRDC) is an international nonprofit environmental organization with more than 3 million members and online activists. Since 1970, our lawyers, scientists, and other environmental specialists have worked to protect the world's natural resources, public health, and the environment. NRDC has offices in New York City, Washington, D.C., Los Angeles, San Francisco, Chicago, Bozeman, MT, and Beijing. Visit us at and follow us on Twitter @NRDC.