what cardboard for sheet mulching?

Is it ok to use cardboard that comes from beer cartons, cereal boxes, etc? I'm just wondering about the dyes used on the boxes. I think the ink in newspapers is ok because it's soy based, but I don't know about the ink used in your basic food and beverage packaging boxes. Any ideas?

I would tend to think that the more bright colors it has would have a bearing on what was in the ink. Certain colors would probably require some exotic dyes. Many people also worry about the glues in corrugated boxes.

There are many opinions on it (here and elsewhere). Many use it with no qualms, while others wouldn't let it near their soil. I'm sure different printers use different inks, but how do we know which are OK or not. Some printers have the habit of pointing out that their inks are safe, but I have never seen anybody point out "This ink will destroy anything in its path. Keep box away from children."

I believe that everybody should do their own research on it, and make their decisions based on 'comfort zone.
I guess that the bottom line is that if it makes you uncomfortable, DON'T use it.

I think the bigger problem with those items is that they'll shed water rather than absorb it. I have some in one area of my garden and it's just sitting there under the mulch like a water barrier. Nothing grows well in that area. In the fall I'll be digging it out or punching a bunch of holes in it. Corrugated cardboard would be better because the air spaces between the layers would hold water and air for decomposition to take place. I'm pretty sure that most of the glue used in that stuff is made from corn starch and water. As far as the ink is concerned, unless you are using a ton of it you should be ok. In the grand scheme the mass of the ink vs the biomass that'll result in growing a garden/forest will be minimal.

I wouldn't have though that those dyes have much in them to be concerned about but perhaps the glues do.

Not sure why but I've never had an issue with newspaper shedding water and I lay it on at least 20 sheets thick. I always soak the newspapers first for a few hours so they are quite soggy when I'm laying them out. I also make sure the ground has a bit of moisture in it. Perhaps it's the combination that keeps it from drying out. There's very little left after 18 months or so. I have neither the resources nor the physical capacity to clear ground any other way. If I happen across some weed mat I'll put that down for a year or so to kill grass then move it somewhere else but I don't come across it all that often, more's the pity.
Edit: Just thought that it might also be a function of soil type. I'm on heavy clay so when it's wet, it stays wet for some time.

Thanks for all your helpful responses. I guess one factor in how fast the cardboard breaks down is climate. Since it's pretty warm here in Athens, GA, it might break down faster than in colder climates.