Is cat food safe for human consumption?
It's perfectly safe. 

Pet food has to go through the same sort of preservation methods as human food in order to give it a good shelf life so it's not going to have nasty foodborne illnesses. Cat and human metabolisms aren't too far off, and cats don't require nutrients which are harmful to humans so it won't hurt you one bit. 

As for whether it would be healthy to eat long term that's a different story and not for this site.