Researchers have found talking on a mobile phone for 30 minutes or longer per week to be linked with a 12 per cent increased risk of developing high blood pressure or hypertension. Almost three-quarters of the global population aged 10 and over own a mobile phone. Mobile phones emit low levels of radiofrequency energy, which has been linked with rises in blood pressure after short-term exposure, the study said. Hypertension is a major risk factor for heart attack and stroke and a leading cause of premature death globally. “It’s the number of minutes people spend talking on a mobile that…