I would like to raise a question here:
what about the sweeteners? canderel and hermesetas and sweet'n'low and every other similar sweetener? Are they being suspected of cancer or not?
I can't answer your question, because nobody can.
The studies in this area show that many of these sweeteners are probably safe, but I would avoid many of these anyway (look here for example:
http://en.wikipedia.org/wiki/Aspartame_controversy).
The list of sweeteners, where you can find decription of side effects too:
http://en.wikipedia.org/wiki/SweetenersBut the problem with these studies is that they can't take into account everytthing, and especially they can't take into account that people will eat larger doses than was assumed, combine sweeteners with other chemicals like dyes, etc.
I read alarming research paper quite long time ago that one family of dyes was proved safe during studies, but when it came to food processing it was used and then eaten in much higher, possibly toxic doses.
Nobody can stop children from drinking 2 bottles of dyed soda a day - and in this respect the safe limit for the dye was exceeded.
Add to this artificial sweeteners, conservants, and (maaany maaany) other additives, and you have a big problem.
One remark though - you can't assume that every dye is harmful. Many people assume that everything signed E...something is harmful by definition. This is not so. For example E300 is vitamin C, and it is not harmful although it has "E" designation.
And nobody does research comparing people eating food with additives and without additives, or people eating food with more harmful and a little safer additives. It is simply impossible to do such a comparison - it is not possible to get food without any additives.
The funny thing is that food without any aditives would not be good and safe - it would spoil quickly.
But as far as sweeteners go I can only tell you that the safest possible sweetener is glucose. And it is not because it has been tested and confirmed that it is completely safe, but because people eat glucose for thousands of years and metabolism adjusted to handle glucose safely. So it does not cause cancer as we understand it, but it still does not mean that it is completely good for us. Glucose is good food for cancers - it is used as contrast in PET for example, because cancers really thrive on it and absorb it quickly.
So the rule of thumb is that we should limit glucose, rather avoid sweeteners if it is possible and avoid other food additives, especially if we find that they are suspicious. This will allow to avoid possible long-term problems with these additives if they cause any.