CINCINNATI — The nation’s largest grocery chain has begun to phase out the use of plastic bags as more Americans grow uncomfortable with their impact on the environment.Kroger Co. will start Thursday at its QFC stores in and around Seattle, with the goal of using no plastic bags at those stores next year. The company said it will be plastic-bag free at all of its nearly 2,800 stores by 2025.Kroger owns Fred Meyer, which has seven stores in Clark County and another dozen in the Portland area. There are six QFC locations in the Portland-Vancouver area, including one on 192nd Avenue in Vancouver.Kroger Co. orders about 6 billion bags each year for its stores in 35 states and the District of Columbia, which cater to almost 9 million people daily through two dozen different grocery chains.The grocer, based in Cincinnati, is seeking customer feedback and will be working with outside groups throughout the transition to reusable bags. Customers will be able to buy reusable bags at its stores for $1 to $2 a piece. While brown paper bags will also be available for free, Kroger says that its goal is to fully transition to reusable bags.