Agriculture groups challenge California Roundup warning

A coalition of a dozen national and Midwestern agricultural groups sued on Wednesday to overturn a California decision that could force the popular weed-killer Roundup to carry warning labels that it can cause cancer.

The lawsuit filed in federal court in Sacramento seeks an injunction barring the state from enforcing what the suit describes as a “false” and “misleading” warning.

It claims California’s decision violates constitutional due-process and free-speech rights and should be superseded by federal regulations.

Roundup’s main ingredient, glyphosate, is not restricted by the U.S. Environmental Protection Agency, and has been used widely since 1974 to kill weeds while leaving crops and other plants alive.

But the International Agency for Research on Cancer, based in Lyon, France, has classified it as a “probable human carcinogen.” That prompted the California Office of Environmental Health Hazard Assessment to add glyphosate this summer to a list of chemicals known to cause cancer. The listing could lead to a requirement for warning labels on the product.

The plaintiffs in the lawsuit include the national wheat and corn growers associations, state agriculture and business organizations in Iowa, Missouri, North Dakota and South Dakota, and a regional group representing herbicide sellers in California, Arizona and Hawaii. The plaintiffs also include St. Louis-based Monsanto Co., which makes Roundup.