Actualy transportation researchers have investigated many aspects of distracted drivers. The findings suggest that the most dangerous times is when the driver takes their eyes off the road or requires two hands. For eating its opening packaging or eating things that require a utensil. One handed eating say an apple, sandwich etc, is less likely to cause a crash. In most cases of eating or drinking you set the item down and use two hands on the wheel when needed.

Cell phone studies show that crahes occur most when drivers are trying to dial the phone, looking to see who is calling, or text messaging. Once you are on the phone and talking one handed the danger decreases but does not diminish. The unique aspect of a cell phone is that you will not set the phone down when two hande operation is needed. This is because of the nature of phone conversastion and you feel rude about ending the conversation so abrubtly.

The pure science aspect of this is called perception reaction time. Its the the time it takes for a driver to percieve danger, react, and stop. Its a combination of those 3 elements. Cell phones, eating, make-up, reading, etc all reduce the perception of danger time and that is the root of the crash.