Biological studies by Stick and Hinkelmann of the effects of static magnetic fields have found that magnetic fields up to 1 Tesla (10,000 Gauss) have no effect on tissue, blood flow, etc. One Tesla is huge. You only get magnetic fields like that in special medical machines (MRI) or in special laboratories specifically designed to create fields that strong. If you ever find yourself near such things, you are briefed on the potential risks of strong magnetic fields. Although most biological tissue is diamagnetic, the response is so weak that everyday magnetic fields, such as from a cell phone, loud speakers, or fridge magnets are far to weak to have any effect.