They're the numbers used by the food industry for additives that give colour and/or flavour, or for preserving shelf life. They became somewhat notorious a decade or two ago when they were linked to hyper-activity/ADD (ADHD) type behaviour. I certainly noticed it in friends kids, after being given colourful sugary things, they would go full-on hyper and invariably climax in tears. In many parts of Europe there have been moves to ban or add warnings for certain additives.