Any distracting gadget is dangerous if you’re driving a car.
One study, in the New England Journal of Medicine, concluded that talking on a phone while driving made you four times more likely to get into an accident, comparable to the increased risk of accident if driving while legally drunk.
It doesn’t seem to make a difference whether the phone is hands-free or not, simply talking on the phone creates the risk.
Does this mean that talking to a passenger might be equally dangerous? Not necessarily.
Most passengers suspend conversation if they become aware that the driver is distracted, driving badly, or in the middle of difficult traffic conditions.
Passengers even add an extra set of eyes and can help prevent accidents by giving helpful warnings to the driver.