A U.S. farm worker and a horticultural assistant have filed lawsuits claiming Monsanto Co.'s Roundup herbicide caused their cancers and Monsanto intentionally misled the public and regulators about the dangers of the herbicide.  The lawsuits come six months after the World Health Organization's cancer research unit said it was classifying glyphosate, the active weed-killing ingredient in Roundup and other herbicides, as "probably carcinogenic to humans."…The lawsuits claim that Roundup was a "defective" product and "unreasonably dangerous" to consumers, and that Monsanto knew or should have known that glyphosate could cause cancer and other illnesses and injuries, failing to properly warn users of the risks…Since the WHO action, some product liability lawyers have been seeking out plaintiffs for potential class-action lawsuits over glyphosate...