Fertility experts from the US have warned that men who tend to use their laptop computers on their laps may find their fertility decreased. The researchers, from the State University of New York at Stony Brook, looked at what effect laptop use might have, given that a warm temperature around the testicles is known to cause sperm damage.
The researchers, who have published their findings in the journal Human Reproduction, showed that using a laptop on the lap increased the temperature of the left side of the scrotum by an average of 2.6° C, and the right by 2.8° C. Previous studies have shown that temperature increases of between one and 2.9° C are associated with negative effects on sperm production and therefore fertility.
The researchers studied 29 healthy males, aged between 21 and 35. Against a constant background room temperature, they measured the normal temperature of their scrotal area and compared it to the temperature while the men used laptops. All the men wore the same clothes during the testing and the tests with and without laptops were performed at the same time of the day. In the first test, a 'fake' laptop was given to the men, so that they could adjust to sit in the position they would if they were using a real laptop. This laptop was taken away, and the man had to sit in the same position for an hour, while his scrotal temperature was measured every three minutes. The second test was conducted in the same way, except the men sat with functioning laptops on their laps. The results showed that even just sitting with the thighs together - a position necessary to balance a laptop on the lap - caused scrotal temperature to rise by about 2.1° C degrees. This increase in temperature was high, but was significantly lower than when the men also used functioning laptops.
Dr Yefim Sheynkin, leader of the research team, said 'the body needs to maintain a proper testicular temperature for normal sperm production and development'. He added: 'Portable computers in a laptop position produce scrotal hyperthermia by both the direct heating effect of the computer and the sitting position necessary to balance the computer'. He went on to say that data shows that 'by 2005, there will be 60 million laptop computers in use in the USA and a predicted 150 million worldwide', adding: 'Continued improvements in power, size and price of laptop computers have favoured their increased use in younger people and laptop sales now exceed those of desktop computers'. Until now, he said, the effect on the temperature of the scrotal area when used on the lap was unknown. Laptops 'are frequently positioned close to the scrotum, and as well as being capable of producing direct local heat, they require the user to sit with his thighs close together to balance the machine, which traps the scrotum between the thighs', he said, which adds to the increase in temperature. The team now plans further studies to see what actual effects laptop heat might have on sperm and, from there, to try and determine an exact amount of time that can be recommended for the safe use of laptops.