The pesticide known as Roundup has been widely used for four decades. It’s a cash cow for Monsanto. But recent scientific studies have determined it’s a carcinogen and court cases are paying out huge damages to victims. Thousands more lawsuits have been filed. And yet many retailers still stock the product for home use. Today, I signed a petition asking Home Depot and Lowes to take the product off their shelves, following the lead of Costco.