By Carey Gillam Bayer better be paying attention to this. The German company’s intended $66 billion acquisition of Monsanto Co. comes amid growing concern over the future of the company’s top-selling weed killer, a chemical called glyphosate that Monsanto introduced to the world 40 years ago as the active ingredient in its Roundup herbicide. Monsanto … Upcoming EPA Meetings on Safety of Monsanto Weed Killer Drawing Scrutiny