Court Rules Against Monsanto, California To Put Cancer Warning On Roundup Critics take issue with Roundup’s main ingredient, glyphosate, which has no color or smell. Monsanto introduced it in 1974 as an effective way of killing weeds . It’s sold in more than 160 countries, and farmers in California use it on 250 types of crops. The chemical is not restricted by the U.S. Environmental Protection Agency, which says it has “low toxicity” and recommends people avoid entering a field for 12 hours after it has been applied. But the International Agency for Research on Cancer, a Lyon, France-based branch of the U.N. World Health Organization, classified the chemical as a “probable human carcinogen.” Shortly afterward, the most populated U.S. state took its first step in 2015 to require the warning labels. Attorneys for California consider the International Agency for Research on Cancer the “gold standard” for identifying carcinogens, and they rely on its findings along with several states, the federal government and other countries, court papers say. Fresno County Superior Court Judge Kristi Kapetan still must issue a formal decision, which she said would come soon. California regulators are waiting for the formal ruling before moving forward with the warnings, said Sam Delson, a spokesman for the state Office of Environmental Health Hazard Assessment. Once a chemical is added to a list of probable carcinogens, the manufacturer has a year before it must attach the label, he said. Teri McCall believes a warning would have saved her husband, Jack, who toted a backpack of Roundup for more than 30 years to spray weeds on their 20-acre avocado and apple farm. He died of cancer in late 2015. “I just don’t think my husband would have taken that risk if he had known,” said Teri McCall, one of dozens nationwide who are suing Monsanto, claiming the chemical gave them or a loved one cancer.