Most of our modern phones or other electronic devices come with SAR values specified. This has led to a lot of discussion about the effects and safe values of SAR values. Let's first talk about the meaning of SAR value first.
SAR value stands for Specific Absorption rate. It roughly means the rate of energy absorbed during the exposure of electromagnetic (EM) waves. SAR value depends on the electric conductivity, density and volume of the object exposed and to the electric field of the emitter. Most electronic devices have a SAR value taking an average human being. The safe value of SAR may be different with different rules and rating. EU rating of safe SAR is 2.0 whereas US rating is below 1.6. Modern devices are set well below the safe SAR value on the basis of physical, chemical and biological point. However MICROWAVE HEARING EFFECT is found to be present well below the safe SAR value. These SAR values are so low that they can almost never have any effect on the users health, atleast not for the next 70-80 years.
However the Negative impact of high SAR values are:
Decrease in sperm count
Cataract problem
Possibility of cancer ( still a hypothesis)
Drain in cognitive ability
Brain and blood barrier effect
Hypersensitivity to EM waves
Insomnia
These effects are far less common and the testing of the devices make sure of people safety but malfunction in the battery can cause to higher exposure and cause health problems as well. Prolonged contact of electronic devices near head or chest region can be controlled just to be safe and avoid its negative impacts. A lot of research is being done by large battery and gadget manufacturers to mitigate the negatives. For now, Phones are much safer than we doubt but less contact can always be a better choice to avoid any hazards nonetheless.