The statistics come from Dan Barnes, the co-founder of Phonesoap, which was displaying its device which sanitises a phone and recharges it.

The innovation is one of several health-related products on show at the Consumer Electronics Show are this year, which are all offering better sanitising and promoting the cause of cleanliness.

Barnes told conference attendees in Las Vegas that people need to look in their pockets and purses to the understand the microbes on their personal gadgets.

The smartphone "is always warm, stored in dark places, so bacterias are growing on your phone", he said.

Barnes said he got the idea after reading a study indicating "that mobile phones are 18 times dirtier than public bathrooms."

He said his $US50 ($A56.40) device uses ultraviolet radiation which "kills the bacteria's DNA, so that they can't live on your phone anymore."

The project originated on Kickstarter where it raised over $63,000, after a goal of $18,000.

"The UV-C light is only on for 3-5 minutes at a time and there is no heat or liquid involved so there is no risk of damaging your phone," Barnes said. "There is a UV-C light on the top and on the bottom of the box so that the UV rays surround your phone for complete sanitization."

For more information check out the Phonesoap website here.