Teenage boys and young men should limit the time that they spend using a laptop computer positioned on their lap, as this may affect their fertility, a new study has found. According to the fertility experts who undertook the research, laptops can increase scrotal temperature, which has been shown to negatively affect sperm development and fertility. The researchers were prompted to carry out a study on this topic due to the increasing popularity of laptops, coupled with the evidence that elevated scrotal temperature can damage sperm. They found that using a laptop increases the left scrotal temperature by an average 2.6 degrees Celsius and the right by an average 2.8 degrees Celsius. Previous studies have shown that increases in scrotal temperatures of between one and 2.9 degrees Celsius can damage sperm and fertility. "By 2005, there will be a predicted 150 million laptop computers in use worldwide. Continued improvements in power, size and price have favoured their increased use in younger people and laptop sales now exceed those of desktop computers", said lead researcher, Dr Yefim Sheynkin of the State University of New York. Until now, the effect of laptops on scrotal temperature when they are used on the lap was not known. "Laptops can reach internal operating temperatures of over 70 degrees Celsius. They 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", Dr Sheynkin explained. He added that for now, the researchers did not know an exact time for safe use. However the study showed that within the first 15 minutes of laptop use, scrotal temperature increased by one degree Celsius. This indicates that it does not take long to reach a point that may affect testicular function. "Until further studies provide more information on this type of thermal exposure, teenage boys and young men may consider limiting their use of laptops on their laps, as long-term use may have a detrimental effect on their reproductive health", Dr Sheynkin added. The research team worked with 29 healthy volunteers, aged 21 to 35, for the purpose of the study. Details are published in the medical journal, Human Reproduction. Source: Irish Health