text: yellow dye # 5 ? --in mountain dew. does yellow #5 cause cancer? doesn't mountain dew still contain yellow # 5? i read long ago that yel.#5 might cause cancer (bladder cancer). i've been hooked on dew 22 yrs! any comments/advice, etc. don't listen to these people. they would rather fool themselves into thinking that the fda actually has their best interests at heart. the same fda that passed vioxx and the evil aspartame (phenalanyline) for use in "nutrasweet".  here is what is known about "yellow #5" (also see source):  fd&c yellow no.5; known to provoke asthma attacks (though the us fda** do not recognise this) and urticaria (nettle rash) in children (the us fda** estimates 1:10 000); also linked to thyroid tumours, chromosomal damage, urticaria (hives) and hyperactivity; tartrazine sensitivity is also linked to aspirin sensitivity; used to colour drinks, sweets, jams, cereals, snack foods, canned fish, packaged soups; banned in norway and austria