You can buy CBD in oils, supplements, soda, even dog food. But some of it violates federal food and drug regulations, prompting concerns over safety and deceptive marketing. With thousands of unproven products flooding the market, the Food and Drug Administration is convening its first public hearing Friday to wrestle with how to regulate cannabidiol (CBD), a cannabis extract already being sold in pills, tinctures, skin lotions,  soda and dog food.