Well blades, I figured it out. The way to repair a bowl that is only slightly broken is pine pitch glue. It is the glue used to secure stone arrow heads onto an arrow shaft. It's only made of pine resin, bees wax and charcoal so it's not dangerous for you like any sort of epoxy would be. I just repaired one of my oldest pieces with it and she hits like new!
i dunno man. i did a quick google search and was getting some hits. stuff like the pine rosin can indeed be toxic. does that mean the thing you're using is? i dunno. but it leads me to believe that if you are putting fire to / heating up the pine pitch glue then i would think there would be fumes of some kind. here are a couple of links. https://en.wikipedia.org/wiki/Rosin http://justinsflintknapping.com/?p=675 the second link says something about toxic and flammable fumes from melting pine pitch down. i have never used this but again it seems like it isn't as safe as it might appear if you're going to be using it on a surface that will come in contact with flame and heat high enough to smoke ganja.
If it just breaks in half, or the bottom of a bowl for a bong, you can wrap aluminum foil really tight around it.., it'll look ghetto, but will work. Lol