If I had a dime for every time I used a zip tie, I would be a rich man. There are few bike projects I get into that do not in some way incorporate zip ties. They are a go to item for me, however they can also be dangerous. A freshly cut zip tie can compete with the most virgin of razor blades in terms of the ability to slice through human skin.
Recently I was securing a pannier to my rear rack and as I reached down to loop the bungee cord under the bottom of the rack my right index finger jammed into the end of a cut zip tie securing a light to my rack and I knew immediately that I was in for days of pain. It was one of those deep cuts in a heavily used area that was just not going to heal quickly. It was a good couple of weeks before it finally healed.
While it would be difficult to melt a razor blade or shark tooth, it is possible to tame the sharp end of a zip tie with a lighter. I highly recommend torching the ends of your zip ties before any blood letting or damage to expensive fabrics occurs.