At the office, the risk of physical injury amounts to paper cuts and carpal tunnel syndrome. Buy the best ergonomic calculator you can afford, do those callisthenic exercises they diagram in airline magazines, and keep a bottle of peroxide and some bandages in your desk drawer, and you should be fine.
The real physical danger comes into play when you leave the office and need to meet with individual or business clients whom you are auditing. Most folks don’t like to have their honesty or mathematical skills called into question. They like it even less when they need to allow you access to their records to either prove your suspicions or their innocence. Throw into the mix the fact that, if you are right, they may face stiff financial penalties or even jail time, and you have a recipe for potential altercations. The ability to manage these situations and maintain a calm, non-threatening manner will get you far.