California would become the first state to require warning labels on sodas and other beverages containing sugar under a bill proposed Thursday. The legislation would require the warning on the front of all beverage containers with added sweeteners that have 75 or more calories in every 12 ounces. The label would warn that drinks with added sugar contribute to obesity, diabetes and tooth decay. The bill was proposed by Senator William Monning, a Democrat. A similar bill was introduced last year in Vermont, but it has been held in a committee. CalBev, the California arm of the Washington, D.C.-based American Beverage Association, noted that the industry already posts calorie counts on the front of many beverage containers and called the Monning bill misleading, because it said just 6 percent of calories in a typical American’s diet came from soda, fruit, sports and energy drinks, compared with 11 percent in candy and desserts.