Microwaves sent out from cell phones can interact with human tissue in ways not yet considered before, according to a researcher at Los Alamos National Labs. The New Mexico lab, often associated with radioactive and bomb research, is home to theoretical biologist Bill Bruno. His paper, titled "What Does Photon Energy Tell us About Cellphone Safety?" describes how microwave radiation could cause damage to the body.
Despite previous arguments against microwave photons being strong enough to break chemical bonds, Bruno argues that this is only true if the number of photons is less than one in a volume of space equivalent to a cubic wavelength. When density is higher, other effects come in to play that could damage you at the cellular level. He goes on to say that the density of microwave photons from cell phones is easily high enough to cause damage to vulnerable structures in the body such as neurons up to a meter long.
The science is a bit complicated, and there have been no definitive studies to suggest what damage smartphones may or may not do. However, it's clear the arguments about the safety of smartphones is far from over.