Men who use mobile phone face increased risk of infertility, according to a new study, although scientists say it was too early to advise men whether they should limit their mobile phone use.
Researchers from US and India led by Ashok Agarwal, director of the Reproductive Research Centre at the Cleveland Clinic, Ohio looked at more than 361 men undergoing checks at a fertility clinic who were classified into three groups according to their sperm count, reported the online edition of the Daily Mail.
Men who used a mobile for more than four hours a day had a 25 percent lower sperm count than men who never used a mobile, the researchers found.
The men with highest usage also had greater problems with sperm quality, with the swimming ability of sperm - a crucial factor in conception - down by a third.
They had a 50 percent drop in the number of properly formed sperm, with just one-fifth looking normal under a microscope, the researchers said.
Almost a billion people are using cell phones around the world and the number is growing in many countries at 20 to 30 percent a year. In another five years the number is going to double.
"People use mobile phones without thinking twice what the consequences may be," Agarwal said.
"It is just like using a toothbrush but mobiles could be having a devastating effect on fertility. It still has to be proved but it could have a huge impact because mobiles are so much part of our lives," he said.
Altogether 361 men in the study were divided into four groups, with 40 never using a mobile, 107 men using them for less than two hours a day, 100 men using them for two-four hours daily and 114 making calls for four or more hours a day.
The main finding was that on four measures of sperm potency - count, motility, viability and morphology, or appearance - there were significant differences between the groups.
The greater the use of mobile phones, the greater the reduction in each measure, Agarwal said.
The results are presented Sunday at the American Society for Reproductive Medicine annual meeting in New Orleans.
The researchers believe the damage could be caused by the electromagnetic radiation emitted by handsets or the heat they generate.
Mobiles may also increase temperature in the groin, if a man was wearing it on a belt or carrying it around in a pocket. The findings suggest millions of men may encounter difficulties in fathering a child due to the widespread use of mobile phone.
Agarwal however said it was too early to advise men trying to start a family about whether they should limit their mobile phone use. He said: "We still have a long way to go to prove this."