Are the artificial colours in junk food linked to cancer?

Not any more: I don't like them either, but each dye gets a thorough going-over as a possible mutagen (the only thing likely to cause cancer apart from preposterously high doses) using the ames test. By 1988, all the apparent mutagens were gone; since then, i've only seen claims of dye mutagens in food (which any good scientist would grab up in a minute) in marginal journals.