The World Health Organization (WHO) urged all countries to get rid of trans fats in their food supply, with laws banning them if necessary. The artery-clogging fats kill half a million people a year and they’re completely unnecessary, the WHO said. Trans fats are used widely to make cookies, crackers, microwave popcorn and to try fry fast food. They are made by processing liquid oils to make them solid or semi-solid and to make them stay fresh longer than liquid fats. But the chemical process used to make them solid like butter also makes them clog arteries just a butter or lard does. They are also found naturally in some meats such as beef and mutton, as well as in dairy products. There is not a good way to remove trans fats from natural foods, but food policy experts agree there’s no place for artificially made trans fats in human diets. The FDA has ruled that partially hydrogenated oils are no longer “generally recognized as safe” or GRAS. As of next month, U.S. food manufacturers may not use trans fats in food products without FDA approval. Some cities, notably New York City, have also banned them.