On Monday, the Campaign to Regulate Marijuana Like Alcohol in Massachusetts announced the installation of a St. Patrick’s Day-themed billboard in Boston that highlights the relative safety of marijuana compared to alcohol. The billboard features a green beer, a glass of whiskey, and a marijuana leaf below the words, “Beer,” “Liquor,” and “Safer,” respectively. It directs viewers to RegulateMass.com/Safer, which details several ways in which marijuana is significantly less harmful than alcohol to…