Andreas Arnold and Peter Itin from University Hospital – Basel did a study that found some evidence that a hot laptop could lead to skin damage that might develop into skin cancer. Although they said that this is very rare, the risk is still real. In addition, it is a known danger to sperm count to keep an electromagnetic field near the scrotum.
Answer: Use a lap desk or something to keep the laptop elevated off the lap a bit. whenever possible, put it on a desk.