Causes of hazardous waste?

Biggest cause is man. However please consider this:

First you have to have Hazardous material. Then after the material has served it's purpose and it is now waste. The question is what hazardous materials can we live without and/or find healthy alternatives for? If not, how can we limit our dependicies on it or how can we cut back on it's use. Then after we've done all that, we see what is left over and determine the best method for disposal that limits or elminates it's danger.