今度はカラメル色素 4-MEI

コーラとかに入っているカラメル色素(に含まれる4-methylimidazoleとか)が発ガン性物質だとか。

California has added 4-MEI to its list of carcinogens and is pursuing legislation that requires any product containing elevated levels to carry a warning label. For 4-MEI, levels higher than 16 micrograms per person per day from an individual product would require a warning.

http://www.webmd.com/food-recipes/news/20110215/group-wants-ban-on-2-types-of-caramel-coloring-in-sodas

カラメル屈折率 (角川ルビー文庫)

逆に発ガン性が全くない物質は何?