Alcohol producers have discovered another way for partyers to get buzzed. But public health officials and lawmakers, concerned about the safety of teens and young adults, are scrambling to take a newly approved product off the market. “As a public health leader, emergency physician and mother of three, I must say powdered alcohol is my worst nightmare,” Joneigh S. Khaldun, the Baltimore City Health Department’s chief medical officer, said Thursday during a hearing in Annapolis on legislation that would ban the sale of powdered alcohol in Maryland for two years. “It’s basically alcoholic Tang.”