Canvas boxing bag pros and cons?

Canvas boxing bag pros and cons? Are there any drawbacks to a canvas boxing bag? Most boxing bags are made of either artificial leather (PU or PVC) or real leather. The boxing bag in my child's bedroom is some kind of artificial leather and the shell has started to shed a fine dust. I do not want this to happen again, because this dust is likely to consist of toxic compounds (phthalates among others) and it is in his bedroom. So I'm looking to replace the exterior of the boxing bag with something better, but I find leather too expensive for my purposes. Next year it will probably be too small and a larger one cannot hang at the same spot. Are there any drawbacks to choosing a canvas bag instead of a fake-leather one? Edit: The fine powder was coming from inside the bag. The filling consisted mostly of some sort of synthetic wool and black bits of plastic, it looked and smelled like the contents of a hooverbag. I'm leaving the question as is, because it's still relevant, just not to my specific problem.