The NAS study said mandatory GE-labeling would give buyers the chance to make "their own personal risk-benefit decisions" about the products. Without it, consumers are deprived of making an informed choice about the goods, the authors wrote. The study "takes a major policy step in calling on the food and agriculture industries to increase transparency regarding GMO foods," the Environmental Working Group in Washington said in a statement. "It acknowledges that as long as companies hide basic facts from consumers, we will be unable to make food choices that reflect our values," Gary Hirshberg, chairman of Just Label It, said in a statement. Another source of debate over GMOs involves safety concerns of glyphosate, the weedkiller that some crops have been modified to tolerate. The chemical, sold by Monsanto Co under the Roundup brand, probably causes cancer, the International Agency for Research on Cancer said last year. Monsanto, the world's largest seed company, rejected the findings.