Researchers find that men who place portable computers on their laps are inadvertently raising the temperature of their scrotums — and possibly damaging their sperm.

Men who regularly balance their laptop computers on their laps when working may be jeopardizing their ability to have children, according to a new study from fertility researchers at the State University of New York at Stony Brook.

The potential risk comes from the heat generated by the laptop computer and the close position of one’s thighs when balancing the computer on one’s lap, the researchers found. This heat is transferred to the scrotum, where the temperature can rise several degrees, putting users within the danger zone for testicular dysfunction.

The findings suggest that young men should place laptop computers on a desk, a table or anywhere else but their own laps.

“I definitely recommend that teenage boys and young males limit the use of laptop computers because the results may be unpredictable,” said lead researcher Yefim Sheynkin, director of male infertility and microsurgery at the university. “Don’t get me wrong — the laptop computer is very useful and helpful. But we need to be cautious.”

Scientists have known for years that an increase of even 1 degree Celsius in testicular or scrotal temperature can decrease the production of healthy sperm by as much as 40 percent. In the Stony Brook study, researchers found that test subjects who sat for an hour with running laptops on their laps had a median increase in scrotal temperature of 2.6 to 2.8 degrees Celsius.

The 29 volunteers, aged 21 to 35, were also asked to sit with their thighs together for an hour without a laptop. This resulted in a median increase in scrotal temperature of 2.1 degrees, suggesting that the act of balancing a laptop computer is just as much to blame as the heat generated by it.

Two unidentified brands of Pentium 4 laptops were used at random in the study. Additionally, the volunteers were required to wear the same type of clothing in both tests to rule out variations caused by differences in underwear and pants. The volunteers’ scrotal temperatures were measured every several minutes with a device attached to both sides of subjects’ scrotums.

More here.