Wi-Fi signals from laptops could be damaging to male fertility, Argentinean researchers have suggested after conducting a simple proximity test.
The team reportedly tested sperm samples from 29 healthy donors after conducting two tests. In the first sperm was placed under a laptop for four hours while in the control the same sperm were left to sit in the same conditions but without the computer present.
Twenty five percent of the sperm exposed to Wi-Fi had stopped moving at the end of the four hours compared to only 14 percent for the control group. Nine percent showed genetic damage compared to only 3 percent for the control.
The difference can't be explained by a simple temperature difference - higher temperatures damage sperm - because the two tests were conducted under identical conditions.
"We speculate that keeping a laptop connected wirelessly to the internet on the lap near the testes may result in decreased male fertility," the scientists conclude.
"Our data suggest that the use of a laptop computer wirelessly connected to the internet and positioned near the male reproductive organs may decrease human sperm quality," Lead researcher Conrado Avendano said.
An important qualification of the study is it examined the effects on sperm as measured ex vivo, that is outside the human body. The scientists recommend further tests to investigate the effect on sperm protected by body tissue.
The basic design of the test has caused some qualms in the scientific community.
"We cannot infer from this study that because a man might use a laptop with Wi-Fi on his lap for more than four hours then his sperm will necessarily be damaged and he will be less fertile," said Dr Allan Pacey of the University of Sheffield told the BBC.
"Ejaculated sperm are particularly sensitive to many factors because outside the body they don't have the protection of the other cells, tissues and fluids of the body in which they are stored before ejaculation.
Scares over electromagnetic fields are nothing new. In 2009, the French Government released a general report on the possible health effects of radio waves from a variety of sources, including phones.
In 2007, a BBC Panorama TV investigation caused controversy after examining the claimed health effects of Wi-Fi use in schools. Critics pointed out that the power of Wi-Fi radio signals was low compared to background levels.