Israeli scientists say they have found high levels of radioactivity in water in the south of the country.
The water in question is salty and not for domestic use
The Ben Gurion University research says that underground water levels were found to be 10 times above normal.
Report author Avner Vengosh denied that the radioactivity was linked to the nearby Dimona nuclear plant.
The study suggests the phenomenon is caused by water washing away a naturally-occurring radioactive metal, radium, from underground rocks.
"This phenomenon has spread throughout the area," Professor Vengosh said, referring to Jordan and the Sinai desert.
He stressed there was no direct danger to human health, because the water is salty and is not normally used for domestic purposes.