A federal judge threw out four lawsuits that allege exposure to the weed killer paraquat can cause Parkinson’s disease, holding her rejection of the expert opinion offered by the plaintiffs doomed their cases.In a written opinion Wednesday, Chief U.S. District Judge Nancy J. Rosenstengel of the Southern District of Illinois ruled Cornell University professor Martin Wells’ testimony did not pass muster under Federal Rule of Evidence 702 or Daubert v. Merrell Dow Pharmaceuticals Inc., 509 U.S. 579 (1993).Wells …