It is impossible at present to predict all the potential adverse biological effects of electromagnetic radiation from mobile phones. Many aspects of the problem are not addressed in the existing scientific literature and require further research. Nonetheless, scientists generally recommend keeping cellular communication time to a minimum.
In a society that constantly puts pressure on people to buy and consume more, ask yourself if you really need to replace your old mobile phone. If you do, make sure that your old phone is disposed of in such a way that it can be recycled.