By Valerie Volcovici WASHINGTON (Reuters) – An environmental group said Monday it had sued two major Californian retailers to stop them selling thicker plastic bags that are supposed to be recyclable but cannot be recycled in the state. The plaintiff, The Last Beach Cleanup, sued supermarket chains Gelson’s and Stater Bros. Markets on Friday in a state superior court, stating they violated Californian recycling laws, contaminated recycling systems and polluted the environment. “The Last Beach Cleanup’s legal action seeks to protect legitimate recycling efforts, save taxpayer funds spent on cle…