With laser light, the radiofrequencies (including radar and microwave), along with infrared and visible light, and the ultraviolet regions of the electromagnetic spectrum are commonly considered to be non-ionizing radiation.
Unlike ionizing radiation, non-ionizing radiation cannot ionize absorbing material. However, it has the ability to increase the temperature of a target material. Depending on exposure time and energy concentration, it can lead to burns.
Ultrasound exposure
Diagnostic ultrasound is widespread mainly in the clinical field and because of this there is increasing concern as to its safety. It is a common belief that low intensity ultrasound is a safe diagnostic imaging tool. One primary supporting factor to this belief is that after four decades of clinical use and millions of patient examinations, there have been no adverse effects reported from diagnostic ultrasound exposures.
Due to the low intensity of diagnostic ultrasound available, laboratory and human data are somewhat limited, and additional studies of biological effects of ultrasound are continuing. At this time there is no positive indication that there are adverse biological effects due to exposure to ultrasonic radiation. However, the possibility has not been ignored and continuing investigations of bioeffects of ultrasound are underway.
Magnetic resonance imaging (MRI)
MRI is common in the clinical and academic field and there is concern as to its safety. At this time, there is no positive indication that there are adverse effects due to the magnetic field strengths or the RF pulses.
Continuing investigations of bioeffects to magnetic fields are ongoing. There is a significant risk to anyone wearing a pace maker or with any metal implants. All personnel with implants must be carefully monitored prior to entering the magnet area.