The result can be a mottled skin discoloration, and with long enough exposure, it can even be permanent. Dr. Kimberley Salkey, an assistant dermatology professor at Eastern Virginia Medical School, said that when examined under a microscope, the skin resembles skin damaged by long-term sun exposure.
There are, of course, many laptop coolers that can be used when a person puts a laptop on his or her lap. Users of gaming laptops, in fact, face the possibility that their laptops will overheat and reduce their performance profile if used extensively to game without a cooler of some sort.
Men face another possible issue: a medical report written in 2004 found that men who used laptops on their laps had elevated scrotum temperatures. In medical speak, they said:
"We don't know the exact frequency and time of heat exposure capable of producing reversible or irreversible changes in spermatogenesis. Studies have shown significant but reversible changes after short-term heating. However, LC produce significant repetitive transient scrotal hyperthermia for years, and insufficient recovery time between heat exposures may cause irreversible or partially reversible changes in male reproductive function."In other words, that sort of heat can cause problems with sperm production, though the study was not long enough to verify a correlation.
The user guides of many manufacturers warn over excessive use of notebooks in people's laps. Here is, of course, another advantage that tablets such as the iPad and upcoming Android tablets have over laptops: they don't get that hot.