In a direct challenge to California regulators and Bay Area environmentalists, the Trump administration Thursday ordered companies to ignore state requirements that businesses warn customers if their products contain glyphosate, a weed killer that has been linked to cancer. The decision flies in the face of three California court rulings against Monsanto, which markets the chemical as Roundup. The agricultural giant faces more than 13,000 suits nationwide by users of Roundup, the world's best-selling herbicide. The U.S. Environmental Protection Agency announced it would no longer approve labels saying glyphosate is known to cause cancer. The state requires companies to warn customers about chemicals known to cause cancer under the Safe Drinking Water and Toxic Enforcement Act. Glyphosate was classified as a probable human carcinogen in 2015 by the International Agency for Research on Cancer, which is part of the World Health Organization. Lawyers for sick clients who were awarded tens of millions of dollars after suing Monsanto introduced evidence that glyphosate can cause genetic damage that leads to non-Hodgkin's lymphoma. They claimed Monsanto ignored that information and published information ghost written" by staffers denying the toxicity of the chemical. Superior Court Judge Winifred Smith said there was clear evidence that Monsanto, after learning of the dangers, "made efforts to impede, discourage or distort scientific inquiry" by regulators.