If the threat of possible brain tumours and premature aging weren't scary enough, a new study on the effects of mobile phone use on human health claims that overexposure to mobiles can cause red blood cells to leak haemoglobin which may lead to kidney stones and even heart disease.

The scientists that conducted the study exposed samples of blood to varying degrees of microwave radiation for ten to 60 hours.

The study, carried out at the European Research Institute for Electronic Components in Bucharest, concluded that even at lower levels than those emitted by mobile phones, the cells leaked haemoglobin.

Powerwatch voices concern

Professor Edward Tuddenham, a haemotologist at the Imperial College Medical School in Hammersmith Hospital, warned that "the accumulation of haemoglobin in the body could result in heart disease or kidney stones."

"We are still very much investigating the biological consequences of mobile phones. But there certainly seems to be enough laboratory studies now saying there are effects, to be very concerned," said a spokesman for Cambridge-based consumer group Powerwatch.