Two new studies have warned of potential health risks from using mobile phones.

The first is a reported study by Professor Lennart Hardell of Örebro University in Sweden which found that children who use mobile phones suffer from significantly higher levels of glioma, a cancer of glial cells.

People who started using mobile phones before the age of 20 suffered a fivefold increase, according to Professor Hardell, and were more at risk from acoustic neuroma, a benign tumour that can cause deafness.

Professor Hardell called for a speeding up of the Mobile Telecommunications and Health Research (MTHR) programme being run in the UK which seeks to analyse the health of more than 90,000 mobile phone users to assess the health issues involved.

The MTHR is currently reporting no short term danger from mobile phone use and other studies back up these findings, however some onlookers are sceptical.

Meanwhile, a second study by the Cleveland Clinic published in the journal Fertility and Sterility reports that keeping a mobile phone in a trouser pocket can significantly affect sperm count for male users.

The study placed sperm samples from 32 subjects within 2.5cm of a mobile phone to simulate a pocket carried phone. They were then exposed to an 850MHz frequency signal for one hour.

The study showed an increase in reactive oxidative stress (or free radicals) and samples also showed decreased amounts of antioxidants which effect the mobility and viability of sperm.

"This is a significant breakthrough because, even though we had a small sample size, we can now develop additional studies to further test what this pilot has revealed," said Dr Edmund Sabanegh, a member of the research team.

"Since many people are now using hands-free sets with their cell phones for various health and safety reasons, it is important that we continue studying this topic to gain a better understanding of the true impact these devices are having on every part of the body."