"Cellphones are 10 times as dirty as a toilet seat," Chuck Gerba, a professor of microbiology at the University of Arizona, told ABC News.
Cellphone users often carry their phones or smartphones all day -- from cars, public transit, offices, restaurants, stores, gyms, public bathrooms, home and often their beds.
Most mobile phone manufacturers do not recommend using anything stronger than solvents such as household cleaners, or alcohol-based solutions to clean a phone. They suggest wiping it with a damp terry cloth, but that would not eliminate germs, bacteria or viruses, researchers said.
AT&T recommends using a hands-free device to minimize phone-to-face exposure.
Wiping down a phone with a small amount of alcohol-based cleaner applied to a cloth can be is effective for removing germs but it can harm a phone's finish.
Many companies have begun to offer products specifically designed to clean and sanitize electronics.
"If one person has the flu virus on their hands, it will be on the hands of 40 percent of the other people in the office within four hours," Gerba told ABC News.
Doctors suggest washing hands properly with either soap and water or an alcohol-based sanitizer before touching the phone or other high-traffic surfaces.