Using a cell phone while driving increases the chance of getting into an accident by 300%, according to Distraction.gov. Using a hands-free device to talk while driving does not significantly lower the danger of using a cell phone.
Your iPhone emits RF radiation which can interfere with a pacemaker or other medical devices. Apple warns to keep the iPhone at least 6 inches from any pacemaker.
If you have a medical condition that may be affected by using the iPhone, such as seizures, blackouts, eye strain, or headaches, consult your doctor before using the iPhone.
Continuous use of any electronic device can cause eye strain and joint stiffness. If you are using your phone for long continuous periods, don’t forget to take breaks.
Don’t use an iPhone with a cracked screen; the glass screen is sharp.
Don’t use a wet iPhone.
Don’t use cables that are broken or frayed.
Don’t leave your phone in a car on a hot day. It can overheat and may be damaged.