Most canvas prints use inks similar to (or actually are) big name inkjet inks like Epson and Canon. Such inks are susceptible to moisture and gaseous toxins and the like. Its kind of tough to generalize the print so much...all of the print houses you've listed use different kinds of canvas and different kinds of inks, and none of them really clearly specify what those inks are or how long they will last (a couple seem to indicate 100+ years, but don't specify under what conditions you might get such a lifetime.)
While you may not notice any change in the short term (i.e. a few years), hanging any canvas print that is printed with anything outside of modern Giclee inks (which are incredibly durable and excellent for canvas) will most likely not have a particularly long lifetime...I would say at most a couple decades, and after a number of years you'll likely start to see some fading or color shift. Only under archival conditions, wherein humidity and air quality and light are all controlled within a specific range, can you hope to achieve 100-200 year longevity.
You might also want to consider a clear protective spray. There are a variety of them available, and I am not sure if some are better suited to canvas prints or not. Usually you just need to evenly spray on a coat of this stuff once a print has fully cured (usually a full day, so if you send it off to a lab it should be cured by the time it gets to you). The spray should give your canvas prints much greater durability in a bathroom environment. It should protect from direct water exposure (splashing from sink or shower), and help protect a bit longer from fading.