I wouldn't, maybe as a treat occasionally. Granted I am obviously not a medical professional. There is so little study on this subject. I wouldn't want to risk messing with the balance of their development cycles, and cause permanent damage somehow.
If your main concern in regarding a 3D is the safety of the eyes, especially for the kids, who will watch it for the long hours, you need to know about two technologies - active and passive viewing. Active or the shutter glasses lead to flickering or crosstalk while watching a 3D TV and start to hurt our eyes or even cause a headache. On the other hand, Passive glasses, which do not open and shut regularly have no flickering issues and allow many hours of television viewing without any problems. Active glasses come with TVs of companies like Sony and Samsung, while Passive glasses come with the LG Cinema 3D TV of the LM series. The latter are fickler free, as well as cheap. So if you decide to go for 3D TVs, do keep these points in your mind. And your kids will also enjoy playing games with the “Dual Play” feature; it is like playing opposite each other with the entire screen at your disposal!
Active definitely would be the risk for your kid’s health since, they delivers image overlapping and flicker a lot while watching for long time. To overcome this issue LG had launched its passive 3d TV last year and now they upgraded their technology, features and 3D TV options too. LG passive TVs are flicker free certified from European certification agencies named as “TUV n Intertek” means these passive TVs are totally safe to view by kids, teens and adults. No harm in viewing for even long time, its 3d glasses are so light weighted and less expensive.
Early this year company had released its LM passive model series, try some TV among them.
With no actual proof, i'm not going to belive active vs passive 3D, specifically an LG branded set is going to be better for a television. No propaganda is going to be able to change the fact that 3D fools the brain into believing the 3D effect.
Here's a youtube video that demonstrates the differences between passive and active 3D glasses on an LG and Samsung TV. You should watch it to get a general feel of what's best for the kids. As seen in the video, if your kids play games or move around a lot while they're watching (as kids usually do), then the active 3D could be quite troublesome. http://www.youtube.com/watch?v=v1wYwIp7Xg4