WASHINGTON, Sept. 20 -- The Missouri Petroleum & Convenience Association (MPCA) has submitted a public comment letter to the U.S. Department of Health and Human Services Food and Drug Administration (FDA) expressing strong opposition to the agency's proposed rule regarding the nicotine yield of cigarettes and certain other combusted tobacco products. The MPCA, a trade association representing various retailers and suppliers across Missouri, argues that the proposal, introduced without adequate c  more