An Indian American scientist who suggested that men who use mobile phone face increased risk of infertility is undertaking a new prospective study to find out its cause and effect.
While the cause and effect has not been proved yet, the first observational study indicated a strong relationship between mobile phone usage and the quantity and quality of semen, Ashok Agarwal, director of the Reproductive Research Centre at the Cleveland Clinic, Ohio said.
It would thus be prudent for men looking forward to start a family to avoid long exposure by limiting call times and switching to wireless devices, he said, noting that almost a billion people are using cell phones around the world almost like a toothbrush.
The new study that would take another 3-4 months to complete would take a look at other suggested co-factors like possible interference from other electronic devices like the PDAs and laptops besides family history and lifestyles.
Agarwal, who is just back after presenting the results of the first study at the American Society for Reproductive Medicine annual meeting in New Orleans, said the new study would take into account observations made by his peers.
Although the results of the first study were "statistically very robust", the new one would cover factors like obesity, use of junk food, type and model used, where it was kept and for how long and the use of quiet and silent mode.
His clinic had already registered 50 patients for the study after approval from the institutional review board and was looking for a sample size of about 200.
Asked if the first study was not alarmist as in his own words they had still a long way to go to prove the link, Agarwal told IANS on phone from Cleveland: "Not really. We are only reporting observations".
In the first study Agarwal's team looked at more than 361 men undergoing checks at his fertility clinic who were classified into three groups according to their sperm count.
They were then split 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.
Men who used a mobile for more than four hours a day had a 25 per cent lower sperm count than men who never used a mobile.
Those 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 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 damage, Agarwal said may be due to electromagnetic radiation emitted by handsets or the heat they generate, but the cause and effect has not been proved yet.